Hostname: page-component-7b7567c8c-fvjsw Total loading time: 0 Render date: 2026-11-14T09:49:04.802Z Has data issue: false hasContentIssue false
  • English
  • Français

Modulation of morphological and biochemical traits using heterosis breeding in coloured cotton

Published online by Cambridge University Press:  12 March 2012

S. N. YUAN,
W. MALIK,
N. BIBI,
G. J. WEN,
M. NI and
X. D. WANG
S. N. YUAN
Affiliation:
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, P. R. China
W. MALIK
Affiliation:
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, P. R. ChinaDepartment of Plant Breeding and Genetics, University College of Agriculture, Bahauddin Zakariya University, Multan, Pakistan
N. BIBI
Affiliation:
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, P. R. China
G. J. WEN
Affiliation:
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, P. R. China
M. NI
Affiliation:
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, P. R. China
X. D. WANG*
Affiliation:
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, P. R. China
*
*To whom all correspondence should be addressed. Email:xdwang@zju.edu.cn
Rights & Permissions [Opens in a new window]

Summary

Heterosis breeding is a potential tool for developing coloured cotton hybrids, having good fibre yield and quality. The objective of the present study was to explore the extent of heterosis breeding for the modulation of fibre quality and biochemical traits during fibre development. The performance of 10 interspecific (Gossypium hirsutum L.×Gossypium barbadense L.) and four intraspecific (Gossypium hirsutum L.×Gossypium hirsutum L.) F1 coloured cotton hybrids and their parents was assessed under field conditions in 2008/9. Two interspecific, two intraspecific F1 coloured cotton hybrids and their parents were used to examine the role and changes in the amount of different biochemicals during the different stages of fibre development (2009). Among hybrids, interspecific brown cotton hybrids (ZUC × ZUA) and interspecific green cotton hybrids (ZUF × ZUA) showed high amounts of useful heterosis for yield, yield components and fibre quality attributes. Analysis of various biochemicals depicted a decline in fibre pH value and flavonoid contents among all hybrids and their parents, with maximum decrease in interspecific hybrids (ZUC × ZUA and ZUF × ZUA) at 15 days post anthesis (DPA). Similarly, a significant increase in the amount of cellulose, glucose and fructose was observed in all genotypes. However, the magnitude of increase was greatest in interspecific coloured cotton hybrids as compared to their parents and intraspecific hybrids. The negative correlation of fibre pH with flavonoid contents and the positive correlation of carbohydrates with cellulose contents (particularly at 15 DPA) suggested the significance of these biochemicals controlling fibre quality. In conclusion, heterosis breeding can be efficiently utilized to develop high-quality coloured cotton hybrids by modulating the synthesis of different biochemicals associated with fibre development and its quality.

Information

Type
Crops and Soils Research Papers
Information
The Journal of Agricultural Science , Volume 151 , Issue 1 , February 2013, pp. 57 - 71
Copyright
Copyright © Cambridge University Press 2012

INTRODUCTION

Heterosis breeding is an important method for plant breeders to improve desirable quantitative and qualitative traits (Srivastava Reference Srivastava2000). The modern concept of heterosis (hybrid vigour) in crops was defined by Shull in 1908 (Randhawa & Singh Reference Randhawa, Singh, Constable and Forester1994). Since then, many plant breeders have documented intraspecific and interspecific heterosis in cotton (Wang et al. Reference Wang, Dutt, Ni, Zhao, Nirania, Khadi, Katageri, Patil, Vamadevaiah, Udikeri and Eshanna2004; Wu et al. Reference Wu, Yin, Guo, Zhu and Zhang2004; Dong et al. Reference Dong, Wu, Jin and Huang2006, Reference Dong, Li, Tang, Li and Zhang2007; Zhu et al. Reference Zhu, Liu and Wang2008; Kantartzi & Roupakias Reference Kantartzi and Roupakias2010; Geddam et al. Reference Geddam, Khadi, Mogali, Patil, Katageri, Nadaf and Patil2011) and found that interspecific crosses displayed more heterosis than intraspecific heterosis, thus having more commercial potential (Baloch et al. Reference Baloch, Lakho and Soomro1993; Zhang et al. Reference Zhang, Wang, Jiang, Hua, Zhang and Dutt2007). The availability of cytoplasmic male sterility (CMS) and fertility restorer parents has facilitated high-yield hybrid seed production throughout the world (Wang et al. Reference Wang, Dutt, Ni, Zhao, Nirania, Khadi, Katageri, Patil, Vamadevaiah, Udikeri and Eshanna2004; Zhang et al. Reference Zhang, Wang, Jiang, Hua, Zhang and Dutt2007; Zhu et al. Reference Zhu, Liu and Wang2008). Heterosis in white-fibred cotton has been extensively studied, both physiologically and genetically (Hao et al. Reference Hao, Yu, Dong, Fan, Ma, Song and Yu2008; Tokatlidis et al. Reference Tokatlidis, Tsikrikoni, Tsialtas, Lithourgidis and Bebeli2008, Reference Tokatlidis, Tsikrikoni, Lithourgidis, Tsialtas and Tzantarmas2011; Gerardeaux et al. Reference Gerardeaux, Jordan-Meille and Pellerin2009); however, naturally coloured cotton has not been so well studied. Today, the demand for textiles manufactured from naturally pigmented cotton is increasing, since a decrease in the use of chemicals for dyeing can be helpful in reducing environmental pollution (Vreeland Reference Vreeland1987; Elesini et al. Reference Elesini, Cuden and Richards2002). However, cultivation of coloured cotton has not accelerated accordingly (Dutt et al. Reference Dutt, Wang, Zhu and Li2004). The fibre quality and yield of coloured cotton are inherently inferior to white cotton fibre (Murthy Reference Murthy2001; Wang & Li Reference Wang and Li2002a; Li et al. Reference Li, Wang, Zhao and Dutt2004; Hua et al. Reference Hua, Yuan, Shamsi, Zhao, Zhang, Liu, Wen, Wang and Zhang2009; Yuan et al. Reference Yuan, Hua, Ni, Li, Wen, Shao, Zhang, Zhu and Wang2010), so cotton breeders continue to be engaged in producing coloured cotton genotypes with high yield and good fibre quality using heterosis breeding (Basu Reference Basu1996). Previously, interspecific as well as intraspecific heterosis has been reported in coloured cotton with an average increase of 18% in agronomic- and yield-related traits (Meredith & Bridge Reference Meredith and Bridge1972; Dutt et al. Reference Dutt, Wang, Zhu and Li2004). But the amount of heterosis for fibre quality traits was very low, ranging from 0 to 0·02 (Wu et al. Reference Wu, Yin, Guo, Zhu and Zhang2004), indicating that fibre quality is probably attributed to the modulation of different metabolic pathways involved in cellulose synthesis during the course of fibre development.

Cotton fibre contains >0·9 cellulose with similar basic mechanisms of cellulose synthesis in different types and species of cotton (Haigler et al. Reference Haigler, Ivanova-Datcheva, Hogan, Salnikov, Hwang, Martin and Delmer2001). Cellulose biosynthesis is complex and controlled on many levels, such as genetics, biophysics, cell biology, biochemistry and environmental interaction (Haigler et al. Reference Haigler, Singh, Wang, Zhang and Paterson2009). Many researchers have documented the relationships of cellulose, carbohydrates, flavonoids and mineral elements with fibre yield and its quality (Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007, Reference Hua, Yuan, Shamsi, Zhao, Zhang, Liu, Wen, Wang and Zhang2009; Yuan et al. Reference Yuan, Hua, Ni, Li, Wen, Shao, Zhang, Zhu and Wang2010). Among these organic compounds, carbohydrates are considered as key sources of energy that act as important osmotic regulators (Martin & Haigler Reference Martin and Haigler2004). The quantity of carbohydrates varies not only among different types of cotton fibres but also at different fibre developmental stages, thus controlling the cotton fibre quality (Gipson Reference Gipson, Mauney and Stewart1986; Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007, Reference Hua, Yuan, Shamsi, Zhao, Zhang, Liu, Wen, Wang and Zhang2009). Flavonoids are another important class of organic compounds involved in the pigmentation of tissues, pollen fertility and regulation of the hormones (Li et al. Reference Li, Ou-Lee, Raba, Amundson and Last1993; Stapleton & Walbot Reference Stapleton and Walbot1994; Shirley Reference Shirley1996). In coloured cotton fibre, this metabolite has negative associations with cellulose and fibre quality because both cellulose and flavonoids share the same substrates and energy during their synthesis (Wang & Li Reference Wang and Li2002b, Reference Wang and Lic; Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Li et al. Reference Li, Wang, Zhao and Dutt2004; Zhao & Wang Reference Zhao and Wang2005). Beside carbohydrates and flavonoids, the pH of the developing fibre also plays a key role in determining the fibre colour and quality. Low pH in the developing fibre favours fibre elongation and secondary wall thickness (Hondo et al. Reference Hondo, Yoshida, Nakagawa, Kawai, Tamura and Goto1992; Dutt et al. Reference Dutt, Wang, Zhu and Li2004), and vice versa.

The objective of the current study was to explore the extent of heterosis for fibre quality, yield and yield components, and to characterize the relationship between different biochemical and fibre quality attributes at different fibre developmental stages in interspecific, intraspecific coloured cotton hybrids and their parents.

MATERIALS AND METHODS

The dynamics of heterosis for fibre yield, yield components and quality was investigated using a set of 10 interspecific and 4 intraspecific hybrids, and 11 parental lines (Table 1), together with a commercial white cotton hybrid (Xiangzamian) used as a control (CK). The study was conducted at the College of Agriculture and Biotechnology, Zhejiang University, Hangzhou China during 2008/9 (30°15′N, 120°10′E; 18 m a.s.l.). The hybrid seeds were produced in 2007 and grown in 2008 and 2009 along with their parents to compare the extent of heterosis. Then, based on their performance during 2008, two interspecific (ZUC × ZUA and ZUF × ZUA), two intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUC, ZUA, ZUF and ZUG) were selected in 2009, to evaluate the role of different biochemical properties (pH value, cellulose, flavonoid, total sugar, sucrose, fructose and glucose) during the course of fibre development.

Table 1.

Plant genotypes used in present study

Experimental design

The seeds of all interspecific and intraspecific coloured cotton hybrids and their parents were sown in April 2008 and 2009 in polythene bags (40 mm diameter × 100 mm high) filled with nutrient-rich soil and placed on an already watered seed bed. The soil was taken directly from the field and placed in the polyethylene bags one week before manual sowing. Each polythene bag contained 2–3 seeds at a depth of 15 mm and covered by a thin layer of fine soil. After sowing, the bags were covered with transparent plastic film to keep the soil moist. After germination (3–5 days), the bags were uncovered during the day but re-covered at night to protect the young seedlings from low temperatures. The surface of the soil was kept moist by watering the seed bed every 2 days. Only one seedling was allowed to grow in each polythene bag to ensure healthy seedlings before transplanting into the field at 15 days old. Seedlings were transplanted into field having clay-loam soil, pH 6·5 and organic matter content of 25·4 g/kg in May. Nitrogen fertilizer (0·12 t/ha) was applied to the experimental plots before transplanting. The experiment was laid out in a randomized complete block design with three replications. Each plot (10·5 m2) consisted of four rows, which were 5 m long with row to row and plant to plant distances of 700 and 400 mm, respectively. The crop density was c. 30 000 plants/ha.

Sampling for yield, yield components and quality attributes

At maturity, 30 healthy plants of each F1 hybrid were selected from each plot on which to record the data on agronomic, yield, yield components and quality attributes. These attributes were the number of sympodial branches, plant height (mm), aborted seed proportion, dry weight per plant (g), number of bolls per plant, boll weight (g), lint proportion, seed cotton yield (t/ha) and lint yield (t/ha). Fibre quality traits were measured using a high volume instrument (HVI). The tensile strength of fibres is determined as the force required to break a bundle of cotton fibres, expressed as (cN/tex). The Tex is a measure of the linear mass density of fibres and is defined as the mass in grams per 1000 m. Fibre fineness is a measure of the maturity and diameter of cotton fibres. A constant mass (2·34 g) of cotton fibres is compressed into a space of known volume and air permeability measurements of this compressed sample are taken. These are termed Micronaire values (mic). The fibre uniformity index provides a relative measure of the uniformity of the length of cotton fibres. It is calculated as the ratio of the average length of all fibres to the average length of the longest 0·50 of the fibres in the sample. Fibre length uniformity affects yarn strength and the efficiency of the spinning process. High-quality cotton has a score of 0·83–0·85. Cotton with a low uniformity index (below 0·79) is likely to have a high proportion of short fibres, will be difficult to process and is likely to produce low-quality yarn. Fibre elongation is measured as the proportional extension of the fibres before a break occurs.

Sampling and analysis for biochemical attributes

The flowers of two interspecific hybrids (ZUC × ZUA (brown) and ZUF × ZUA (green)) two intraspecific hybrids (ZUC × ZUG (brown) and ZUF × ZUG (green)) and their parents were tagged at the day of anthesis. Developing bolls were harvested from 0 to 50 days post-anthesis (DPA) with an interval of 5 days. Then fibre was separated from the seeds, kept in liquid nitrogen and stored at −80 °C for further analysis.

Total flavonoids were extracted following the method described by Dutt et al. (Reference Dutt, Wang, Zhu and Li2004) and quantified using rutin (quercetin-3-O-rutinoside; Sigma Aldrich, Cat No. 5143) as a standard curve (Wang et al. Reference Wang, Xu and Wei1999). For quantification of cellulose in developing cotton fibre, samples were collected from 15 to 50 DPA at 5-day intervals, digested in an acetic–nitric reagent (acetic acid: nitric acid: water = 8: 1: 2 v/v) and measured by following the procedure of Updegraff (Reference Updegraff1969). The pH value of harvested samples was determined according to Dutt et al. (Reference Dutt, Wang, Zhu and Li2004), while the amount of soluble sugars and glucose were calculated using the methodology of Dubois et al. (Reference Dubois, Gilles, Hamilton, Rebers and Smith1956). However, concentration of fructose and sucrose was measured using the method developed by Hendrix (Reference Hendrix1993).

Data analysis

The data were processed using SAS 9·1 and the graphs were generated using Microsoft Excel. Useful heterosis was worked out as the proportional difference in performance of hybrids from the control (cvar Xiangzamian):

$${\rm Useful}\,{\rm heterosis} = \left[ {{\rm F}_{\rm 1} -{\rm CK}} \right]/{\rm CK}$$

The significance of the heterosis was determined using a t test. Negative values for useful heterosis imply that the value of the trait being analysed is lower than that of the control variety.

RESULTS

Mean performance and heterosis

The interspecific F1 hybrids were significantly better than intraspecific hybrids for agronomic traits, boll numbers and fibre quality attributes. Maximum mean performance with highest magnitude of useful heterosis for number of sympodial branches (0·473), number of nodes per plant (0·968) and plant height (0·457) was observed in interspecific brown cotton hybrids ZUB × ZUD (Table 2). Among the intraspecific crosses, the brown cotton hybrids (ZUI × ZUH) showed the best performance, with positive and highly significant useful heterosis for the same parameters but still much lower than for interspecific hybrids (Table 2). Similarly for yield components, the brown interspecific hybrids ZUC × ZUA and ZUJ × ZUD exhibited positive and highly significant amount of useful heterosis for number of bolls (0·57) and seed cotton yield (0·204) (Table 3). However, useful heterosis for boll weight was negative in both inter- and intraspecific hybrids (Table 3). For quality attributes, interspecific green hybrids ZUF × ZUA and ZUA × ZUF showed positive, highly significant amounts of useful heterosis for fibre length (0·177) and fibre strength (0·195), whereas intraspecific hybrids exhibited negative and significant amount of useful heterosis for the same parameters, except ZUF × ZUG (Table 4).

Table 2.

Performance of cotton lines and heterosis for agronomic attributes in 2008 and 2009 in Hangzhou, China

* I = Interspecific crosses, II = Intraspecific crosses, III = Parents.

ns = not significant.

Table 3.

Performance of cotton lines and heterosis for yield and yield components in 2008 and 2009 in Hangzhou, China

ns: not significant.

Table 4.

Performance of cotton lines and heterosis for fibre quality traits in 2008 and 2009 in Hangzhou, China

ns: not significant.

Synthesis of flavonoids, cellulose and pH of fibre

Synthesis of flavonoids, cellulose and fibre pH at different fibre developmental stages, i.e. 5–50 DPA, was measured in interspecific (ZUC × ZUA and ZUF × ZUA) and intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUA, ZUC, ZUF and ZUG), as shown in Table 5. There were significant differences in flavonoid concentration among the parents and hybrids: the maximum amount of flavonoids was found at 5 DPA decreased continuously during the course of fibre development in both hybrids and their parents.

Table 5.

Correlation coefficient (r) between cotton fibre quality and physiological attributes

ns: not significant.

Among parents, the amount of flavonoids was highest in upland brown cotton (ZUC), followed by upland green (ZUF) cotton. Similarly, the greatest increase in flavonoid content in comparison with the mean performance of their parents at all fibre developmental stages was observed in the intraspecific green hybrid (ZUF × ZUG), while the lowest was found in the interspecific green hybrid (ZUF × ZUA) (Fig. 1).

Fig. 1.

Dynamics of flavonoid concentration at different cotton fibre developmental stages (5, 10, 15, 20, 25, 30, 35 and 50) in interspecific hybrids (ZUC × ZUA and ZUF × ZUA), intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUC, ZUA, ZUF and ZUG). Bars in the histogram are standard errors.

The synthesis and accumulation of cellulose were accelerated along with the fibre developmental stages (15–50 DPA) with a large increase from 15 to 20 DPA in hybrids and their parents. However, no significant differences were observed between hybrids and their respective parents at 15 DPA. Among the parents, Sea Island white cotton (ZUA) exhibited the maximum cellulose content during the entire course of fibre maturation, followed by upland white cotton (ZUG). The amount of cellulose was similar in hybrids derived from same species but significant differences were observed between interspecific (ZUC × ZUA and ZUF × ZUA) and intraspecific (ZUC × ZUG and ZUF × ZUG) hybrids, with distinct gains in interspecific hybrids from 20 to 50 DPA (Fig. 2).

Fig. 2.

Dynamics of cellulose concentration at different cotton fibre developmental stages (15, 20, 25, 30, 35 and 50) in interspecific hybrids (ZUC × ZUA and ZUF × ZUA), intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUC, ZUA, ZUF and ZUG). Bars in the histogram are standard errors.

The results of fibre pH revealed a continuous decline from 0 to 15 DPA, followed by a gradual increase at later stages. However, the cellular environment was acidic during the whole process of fibre development. At 15 DPA, significant differences were observed not only between parents and hybrids but also within parents and hybrids (Fig. 3).

Fig. 3.

Dynamics of pH value at different cotton fibre developmental stages (0, 5, 10, 15, 20, 25, 30 and 35) in interspecific hybrids (ZUC × ZUA and ZUF × ZUA), intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUC, ZUA, ZUF and ZUG). Bars in the histogram are standard errors.

Synthesis of carbohydrates

Significant variation in carbohydrates (total sugar, sucrose, glucose and fructose) was observed in hybrids and their parents (Table 6). The concentration of total sugars increased from 0 to 10 DPA, followed by a decrease up to 35 DPA, irrespective of the parents and hybrids. Interspecific hybrids (ZUC × ZUA and ZUF × ZUA) were superior to intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) for total sugars with respect to their mean values. Among parents white cotton (ZUA and ZUG) had higher sugar content in comparison with brown (ZUC) and green (ZUF) cotton.

Table 6.

Dynamic change of cotton fibre carbohydrate contents at different developmental stages of materials in 2009 Hangzhou, China

For sucrose contents, a cyclical pattern of alternating increases and decreases was observed. The peak value was seen at 0 DPA, followed by a decline to a minimum concentration at 15 DPA, then another increase up to 30 DPA (although the peak value here was less than that found on the day of anthesis) and another decline to 35 DPA. However, the mean values for sucrose contents varied significantly between hybrids, being highest in interspecific crosses (Table 5). When parents were compared, white cotton (ZUA and ZUG) fibre was found to contain more sucrose compared to coloured cotton (ZUC and ZUF).

A significant increase in glucose concentration was observed from 0 to 5 DPA, with a sharp decline up to 15 DPA and then another increase up to 30 DPA in parents as well as their hybrids. However, the mean performance of the hybrids was significantly higher than their respective parents, interspecific hybrids being superior for glucose concentration.

The quantity of fructose increased significantly with the advancement of fibre development. Both hybrids and their parents had attained a peak value at 10 DPA, followed by a sharp decline up to 35 DPA, a stage when fibre elongation ceased. However, marked variations were observed between white cotton and coloured cotton, with the former having higher fructose concentrations (Table 6). Among hybrids and their parents, interspecific hybrids (ZUC × ZUA and ZUF × ZUG) were found to contain more fructose than intraspecific hybrids and their respective parents.

Correlation coefficient among different biochemical and fibre quality attributes

There was a close association among cellulose (50 DPA), fibre quality and biochemical traits during different fibre developmental stages in interspecific, intraspecific hybrids and their parents. During the earlier fibre developmental stages (0–20 DPA), carbohydrate levels were positively correlated with fibre quality attributes (fibre length, fibre strength, fibre uniformity and elongation). However, a highly significant positive correlation was observed between total sugars and sucrose with cellulose contents during the whole course of fibre development, with high amounts found in the fibre elongation phase compared to the fibre maturation phase (Table 5). Similarly, the pH and flavonoid contents were negatively correlated with both cellulose and fibre quality attributes during the whole course of fibre development (0–35 DPA).

DISCUSSION

Heterosis breeding is an effective tool to enhance the yield and enrich quality parameters (Srivastava Reference Srivastava2000; Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Li Reference Li2005) and availability of CMS and restorer factors facilitated the production of cotton hybrids at commercial scale (Wang et al. Reference Wang, Dutt, Ni, Zhao, Nirania, Khadi, Katageri, Patil, Vamadevaiah, Udikeri and Eshanna2004; Zhang et al. Reference Zhang, Wang, Jiang, Hua, Zhang and Dutt2007). Useful heterosis has more practical implications as it conveys a more straightforward message to plant breeders and farmers, compared to mid-parent and best parent heterosis (Hua et al. Reference Hua, Zhou, Huang, Zhu, Yu, Zhang and Liu1963; Dong et al. Reference Dong, Li, Tang, Li and Zhang2007; Zhu et al. Reference Zhu, Liu and Wang2008; Geddam et al. Reference Geddam, Khadi, Mogali, Patil, Katageri, Nadaf and Patil2011). In the present study, the performance of interspecific coloured cotton hybrids regarding yield was significantly higher than intraspecific hybrids, thus demonstrating the commercial potential of interspecific hybrids (Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Zhao & Wang Reference Zhao and Wang2005; Kantartzi & Roupakias Reference Kantartzi and Roupakias2010).

A useful significant and positive heterosis was observed for a number of bolls, seed cotton yield and lint yield, indicating the importance of hybrid vigour for these traits; this supports the findings of many other studies (Galanopoulou-Sendouca & Roupakias Reference Galanopoulou-Sendouca and Roupakias1999; Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Khan et al. Reference Khan, Hassan, Kumbhar, Marwat, Khan, Parveen, Aimen and Saeed2009; Abd-El-Haleem et al. Reference Abd-El-haleem, Metwali and Al-Felaly2010). However, high heterosis for number of bolls in the case of interspecific hybrids did not always corresponded to high heterosis for lint yield. This revealed the fact that lint yield did not necessarily depend on high heterotic expression of all yield components (Galanopoulou-Sendouca & Roupakias Reference Galanopoulou-Sendouca and Roupakias1999; Kapoor et al. Reference Kapoor, Singh and Maheshwari2002; Dong et al. Reference Dong, Li, Tang, Li and Zhang2007). Except for interspecific green cotton hybrids, all combinations that were found to be heterotic for yield and yield components failed to exhibit good performance for fibre quality attributes, thus indicating that yield and quality traits cannot be exploited simultaneously (Preetha & Raveendran et al. Reference Preetha and Raveendran2008). However, the superiority of interspecific green hybrids for fibre length and strength indicated that this might be due to the phenomenon of over-dominance (Soomro et al. Reference Soomro, Kumbhar and Larik2009) or due to the presence of some dominant allele (Kowsalya et al. Reference Kowsalya, Raveendran and Puspalatha1999).

Cellulose is the major component of cotton fibre and high amounts of cellulose always guaranteed a better quality of cotton fibre (Martin & Haigler Reference Martin and Haigler2004). In the present study, the amount of cellulose was lower in coloured cotton fibres compared to white cotton fibre, and might be due to flavonoid synthesis (Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007, Reference Hua, Yuan, Shamsi, Zhao, Zhang, Liu, Wen, Wang and Zhang2009). However, a significantly higher amount of cellulose after 15 DPA in the interspecific coloured cotton hybrid as compared to their parental lines suggested the accumulation of dominant alleles at different loci for cellulose synthesis. This favoured the phenomenon of heterosis breeding to modulate the cellulose synthesis in coloured cotton hybrids (Kowsalya et al. Reference Kowsalya, Raveendran and Puspalatha1999; Dutt et al. Reference Dutt, Wang, Zhu and Li2004). Analysis of flavonoid biosynthesis revealed maximum accumulation in parents and their respective hybrids at 5 DPA with a continuous decrease during the remainder of the fibre development phase (Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007; Reference Hua, Yuan, Shamsi, Zhao, Zhang, Liu, Wen, Wang and Zhang2009). It is suspected that this continuous decrease might be due either to the synthesis of lignin or an increase in the amount of cellulose present (Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007). Moreover, at maturity (50 DPA) Sea Island white (ZUA), upland white (ZUG) and the interspecific green cotton (ZUF × ZUA) hybrid have lower amounts of flavonoids corresponding to high amounts of cellulose at the same stage.

Many other researchers have documented a close relationship between pigmentation (flavonoids) and the pH of specific plant tissues (Mol et al. Reference Mol, Grotewold and Koes1998; Wang et al. Reference Wang and Li2002b, Reference Wang and Lic; Yoshida et al. Reference Yoshida, Kitahara, Ito and Kondo2006). The observed differences in the fibre pH and flavonoid contents of parents, i.e. brown, green and white, and their hybrids revealed that pH value might have some effect on the synthesis of the flavonoid contents of developing fibres (Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007). Rapid and massive accumulation of cellulose and a sharp decline in the fibre pH during 15–20 DPA has also suggested a close relationship between cellulose synthesis and pH of developing fibres (Basra & Malik Reference Basra and Malik1984; Dutt et al. Reference Dutt, Wang, Zhu and Li2004). In agreement with this, the present study found that white Sea Island cotton (ZUA) and interspecific green hybrid (ZUF × ZUA) exhibited low fibre pH values during 15–20 DPA, in contrast to maximum amount of cellulose and good fibre quality. The lower pH value is helpful in maintaining the constant turgor state of developing cotton-fibre cells (Basra & Malik Reference Basra and Malik1983), offering resistance to radial expansion (Martin et al. Reference Martin, Bhatt and Baumann2001) and finally allowing unidirectional rapid growth of the developing cotton fibre (Seagull Reference Seagull1992; Wilkins & Jernstedt Reference Wilkins, Jernstedt and Basra1999; Martin et al. Reference Haigler, Ivanova-Datcheva, Hogan, Salnikov, Hwang, Martin and Delmer2001). In the present study, the increase in total sugar contents up to 10 DPA may be due to import of sugar from other parts of plant to the developing cotton boll (a carbohydrate sink), which might be consumed for cellulose synthesis during later stages of fibre development (Thaker et al. Reference Thaker, Rabadia and Singh1999). Among the parents, the green cotton fibre (ZUF) showed the highest sugar contents but did not have high cellulose contents or good fibre quality. This might be due to the fact that synthesis of green pigment consumed more amount of energy, which otherwise could be used for the synthesis of cellulose (Dutt et al. Reference Dutt, Wang, Zhu and Li2004; Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007). But in the case of the interspecific green hybrid, the maximum amount of sugar corresponded to high cellulose contents, fibre length and fibre strength. This may be due to regulation or accumulation of genes controlling carbohydrate flow and efficiency of carbohydrate utilization during the course of fibre development (Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007) hence indicating the significance of heterosis breeding. The reduction in the amount of sucrose contents might be due to its degradation into glucose and fructose, which in turn was exploited to maintain the turgor pressure of the fibre cell, especially during the rapid elongation phase (15 DPA). The increase in the amount of glucose and fructose in all hybrids and parents up to 10 DPA indicated that sucrose was inverted and glucose and fructose were stored during primary wall synthesis. However, at later stages of fibre development the glucose and fructose contents decreased, suggesting their involvement in secondary cell wall development (Jaquet et al. Reference Jaquet, Buchala and Meier1982). Similarly, low sucrose contents corresponded to low cellulose contents and poor fibre quality in parental-coloured cotton. In contrast to this, high cellulose contents with good fibre quality in both brown and green interspecific hybrids might be due to high levels of sucrose at 15 DPA (Zhang et al. Reference Zhang, Shu, Hu, Cheng, Wang and Zhou2009).

Highly significant positive correlation between carbohydrates, cellulose contents and fibre quality traits (except micronair) suggested that various metabolic activities required high amounts of carbohydrates as a source of energy to synthesize cellulose during the cotton fibre development particularly at 15 DPA (Jaquet et al. Reference Jaquet, Buchala and Meier1982; Thaker et al. Reference Thaker, Rabadia and Singh1999). Higher amounts of cellulose assured good fibre quality because cotton fibre maturity, strength and extensibility are directly dependent on the amount of cellulose (Hsieh Reference Hsieh and Basra1999; Ruan et al. Reference Ruan, Llewellyn and Furbank2001; Ruan Reference Ruan2005; Haigler Reference Haigler, Brown and Saxena2007; Wang et al. Reference Wang, Shu, Cheng, Mcgiffen, Zhang, Xu and Zhou2009; Zhang et al. Reference Zhang, Shu, Hu, Cheng, Wang and Zhou2009). The negative correlation between high amounts of flavonoids with cellulose and fibre quality during cotton fibre development showed that flavonoid biosynthesis consumed a large amount of carbohydrates, sharing the same energy for cellulose synthesis during cotton fibre development (Hua et al. Reference Hua, Wang, Yuan, Shao, Zhao, Zhu and Jiang2007). Genes involved in the synthesis of flavonoids also inhibit the development of cotton fibres (Richmond Reference Richmond1943). The significant negative correlation of fibre pH with cellulose and fibre quality traits, especially at the rapid elongation stage (15 DPA) of the developing fibre, revealed that a low pH value was favourable for fibre cell elongation by maintaining the cell turgor pressure and secondary wall development (Seagull Reference Seagull1992; Wilkins & Jernstedt Reference Wilkins, Jernstedt and Basra1999; Martin et al. Reference Martin, Bhatt and Baumann2001).

The exploitation of heterosis by the introgression of useful novel alleles from elite genotypes belonging to upland and Sea Island cotton could be an effective tool for improving the fibre quality of coloured cotton. Coloured cotton genotypes in the present study always revealed inferior fibre quality, associated with lowered contents of carbohydrates and cellulose. Similarly, the negative correlation of flavonoids and fibre pH with cellulose and fibre quality suggested that flavonoid biosynthesis consumed a large amount of carbohydrates, shared the same energy as cellulose synthesis and ultimately affected fibre development. However, interspecific hybrids exhibited high contents of carbohydrate and cellulose and hence high contents of the desired fibre quality as compared to their parents. In conclusion, there is no doubt that heterosis breeding has valuable applied prospective to modulate the synthesis of different biochemicals associated with fibre quality in coloured cotton.

This work was supported by the National Basic Research Program of China (the 973 Program: 2004CB11730502) and the Natural Science Foundation of Zhejiang (Y306093) and Zhejiang Technology Program (2008C22087).

References

Abd-El-haleem, S. H. M., Metwali, E. M. R. & Al-Felaly, A. M. M. (2010). Genetic analysis of yield and its components of some Egyptian cotton (Gossypium barbadense L.) varieties. World Journal of Agricultural Sciences 6, 615–621.Google Scholar
Baloch, M. J., Lakho, A. R. & Soomro, A. H. (1993). Heterosis in interspecific cotton hybrids. Pakistan Journal of Botany 25, 13–20.Google Scholar
Basra, A. S. & Malik, C. P. (1983). Dark metabolism of CO2 during fibre elongation of two cottons differing in fibre lengths. Journal of Experimental Botany 34, 1–9.CrossRefGoogle Scholar
Basra, A. S. & Malik, C. P. (1984). Development of the cotton fiber. International Review of Cytology 89, 65–113.CrossRefGoogle Scholar
Basu, A. K. (1996). Current genetic research in cotton in India. Genetica 97, 279–290.CrossRefGoogle Scholar
Dong, H. Z., Li, W. J., Tang, W., Li, Z. H. & Zhang, D. M. (2007). Heterosis in yield, endotoxin expression and some physiological parameters in Bt transgenic cotton. Plant Breeding 126, 169–175.CrossRefGoogle Scholar
Dong, J., Wu, F. B., Jin, Z. & Huang, Y. (2006). Heterosis for yield and some physiological traits in hybrid cotton Cikangza 1. Euphytica 151, 71–77.CrossRefGoogle Scholar
Dubois, M., Gilles, K. A., Hamilton, J. K., Rebers, P. A. & Smith, F. (1956). Colorimetric method for determination of sugars and related substances. Analytical Chemistry 28, 350–356.CrossRefGoogle Scholar
Dutt, Y., Wang, X. D., Zhu, Y. G. & Li, Y. Y. (2004). Breeding for high yield and fibre quality in coloured cotton. Plant Breeding 123, 145–151.CrossRefGoogle Scholar
Elesini, U. S., Cuden, A. P. & Richards, A. F. (2002). Study of green cotton fibres. Acta Chimica Slovenica 49, 815–833.Google Scholar
Galanopoulou-Sendouca, S. & Roupakias, S. (1999). Performance of F1 hybrids and its relation to the mean yield of advanced bulk generations. European Journal of Agronomy 11, 53–62.CrossRefGoogle Scholar
Geddam, S. B., Khadi, B. M., Mogali, S., Patil, R. S., Katageri, I. S., Nadaf, H. L. & Patil, B. C. (2011). Study of heterosis in genetic male sterility based diploid cotton hybrids for yield, yield components and fibre quality characters. Karnataka Journal of Agriculture Sciences 24, 118–124.Google Scholar
Gerardeaux, E., Jordan-Meille, L. & Pellerin, S. (2009). Radiation interception and conversion to biomass in two potassium-deficient cotton crops in South Benin. Journal of Agricultural Science, Cambridge 147, 155–168.CrossRefGoogle Scholar
Gipson, J. R. (1986). Temperature effects on growth, development, and fiber properties. In Cotton Physiology (Eds Mauney, J. R. & Stewart, J. M.), pp. 47–56. Memphis, TN: Cotton Foundation.Google Scholar
Haigler, C. H. (2007). Substrate supply for cellulose synthesis and its stress sensitivity in cotton fibre. In Cellulose: Molecular and Structural Biology (Eds Brown, R. M. & , I.Saxena, M.), pp. 147–168. New York: Springer.CrossRefGoogle Scholar
Haigler, C. H., Ivanova-Datcheva, M., Hogan, P. S., Salnikov, V. V., Hwang, S., Martin, L. L. & Delmer, D. P. (2001). Carbon partitioning in cellulose synthesis. Plant Molecular Biology 47, 29–51.CrossRefGoogle ScholarPubMed
Haigler, C. H., Singh, B., Wang, G. & Zhang, D. (2009). Genomics of cotton fibre secondary wall deposition and cellulose biogenesis. In Genetics and Genomics of Cotton, Plant Genetics and Genomics: Crops and Models 3 (Ed. Paterson, A. H.), pp. 385–417. New York: Springer Science + Business Media, LLc.CrossRefGoogle Scholar
Hao, J. J., Yu, S. X., Dong, Z. D., Fan, S. L., Ma, Q. X., Song, M. Z. & Yu, J. W. (2008). Quantitative inheritance of leaf morphological traits in upland cotton. Journal of Agricultural Science, Cambridge 146, 561–569.CrossRefGoogle Scholar
Hendrix, D. L. (1993). Rapid extraction and analysis of nonstructural carbohydrates in plant tissues. Crop Science 33, 1306–1311.CrossRefGoogle Scholar
Hondo, T., Yoshida, K., Nakagawa, A., Kawai, T., Tamura, H. & Goto, T. (1992). Structural basis of blue-colour development in flower petals from Commelina communis. Nature 358, 515–518.CrossRefGoogle Scholar
Hsieh, Y. L. (1999). Structural development of cotton fibres and linkage in fibre quality. In Cotton Fibers: Developmental Biology, Quality Improvement and Textile Processing (Ed. Basra, A. S.), pp. 137–166. New York: The Haworth Press.Google Scholar
Hua, S. J., Wang, X. D., Yuan, S. N., Shao, M. Y., Zhao, X. Q., Zhu, S. J. & Jiang, L. X. (2007). Characterization of pigmentation and cellulose synthesis in colored cotton (Gossypium hirsutum) fibers. Crop Science 47, 1540–1546.CrossRefGoogle Scholar
Hua, S. J., Yuan, S. N., Shamsi, I. H., Zhao, X. Q., Zhang, X. Q., Liu, Y. X., Wen, G. J., Wang, X. D. & Zhang, H. P. (2009). A comparison of three isolines of cotton differing in fiber color for yield, quality, and photosynthesis. Crop Science 49, 983–989.CrossRefGoogle Scholar
Hua, X. N., Zhou, H., Huang, J. Q., Zhu, S. L., Yu, S. J., Zhang, J. S. & Liu, X. M. (1963). The use of heterosis in the interspecific F1 hybrids between G. hirsutum and G. barbadense. Acta Agronomica Sinica 2, 1–24.Google Scholar
Jaquet, J. P., Buchala, A. J. & Meier, H. (1982). Changes in the non-structural carbohydrate content of cotton (Gossypium spp.) fibres at different stages of development. Planta 156, 481–486.CrossRefGoogle ScholarPubMed
Kantartzi, S. K. & Roupakias, D. G. (2010). Study of apomictic seed formation in interspecific, Gossypium barbadense × G. hirsutum, cotton hybrids. International Journal of Botany 6, 164–169.CrossRefGoogle Scholar
Kapoor, C. J., Singh, M. & Maheshwari, R. V. (2002). Heterosis for yield and yield attributing traits in desi cotton. Journal of Cotton Research and Development 16, 182–183.Google Scholar
Khan, N. U., Hassan, G., Kumbhar, M. B., Marwat, K. B., Khan, M. A., Parveen, A., Aimen, U. & Saeed, M. (2009). Combining ability analysis to identify suitable parents for heterosis in seed cotton yield, its components and lint% in upland cotton. Industrial Crops and Products 29, 108–115.CrossRefGoogle Scholar
Kowsalya, R., Raveendran, T. S. & Puspalatha, T. (1999). Heterosis and combining ability analysis for seed quality traits in Gossypium hirsustum L. Madras Agricultural Journal 86, 127–134.Google Scholar
Li, J., Ou-Lee, T., Raba, R., Amundson, R. G. & Last, R. L. (1993). Arabidopsis flavonoid mutants are hypersensitive to UV-B irradiation. Plant Cell 5, 171–179.CrossRefGoogle ScholarPubMed
Li, J. F. (2005). Research on Chinese cotton hybrid vigor utilization. Jiangxi Cotton 27, 3–7.Google Scholar
Li, X., Wang, X. D., Zhao, X. Q. & Dutt, Y. (2004). Improvement of cotton fiber quality by transforming the acsA and acsB genes into Gossypium hirsutum L. by means of vacuum infiltration. Plant Cell Reports 22, 691–697.CrossRefGoogle ScholarPubMed
Martin, C., Bhatt, K. & Baumann, K. (2001). Shaping in plant cells. Current Opinion in Plant Biology 4, 540–549.CrossRefGoogle ScholarPubMed
Martin, L. K. & Haigler, C. H. (2004). Cool temperature hinders flux from glucose to sucrose during cellulose synthesis in secondary wall stage cotton fibers. Cellulose 11, 339–349.CrossRefGoogle Scholar
Meredith, M. R. Jr. & Bridge, R. R. (1972). Heterosis and gene action in cotton, Gossypium hirsutum L. Crop Science 12, 304–310.CrossRefGoogle Scholar
Mol, J., Grotewold, E. & Koes, R. (1998). How genes paint flowers and seeds. Trends in Plant Science 3, 212–217.CrossRefGoogle Scholar
Murthy, M. S. S. (2001). Never say dye: the story of coloured cotton. Resonance 6, 29–35.CrossRefGoogle Scholar
Preetha, S. & Raveendran, T. S. (2008). Combining ability and heterosis for yield and fibre quality traits in Line × Tester crosses of upland cotton (Gossypium hirsutum L.). International Journal of Plant Breeding and Genetics 2, 64–74.CrossRefGoogle Scholar
Randhawa, L. S. & Singh, T. H. (1994). Heterosis breeding for crossing parent yield barriers in cotton. In Proceedings of the World Cotton Research Conference 1, Challenging the Future (Eds Constable, G. A. & Forester, N. W.), pp. 342–345. Brisbane, Australia: CSIRO.Google Scholar
Richmond, T. R. (1943). Inheritance of green and brown lint in upland cotton. Journal of the American Society of Agronomy 35, 967–975.CrossRefGoogle Scholar
Ruan, Y. L. (2005). Recent advances in understanding cotton fibre and seed development. Seed Science Research 15, 269–280.CrossRefGoogle Scholar
Ruan, Y. L., Llewellyn, D. J. & Furbank, R. T. (2001). The control of single-celled cotton fiber elongation by developmentally reversible gating of plasmodesmata and coordinated expression of sucrose and K+ transporters and expansin. Plant Cell 13, 47–60.Google Scholar
Seagull, R. W. (1992). A quantitative electron microscopic study of changes in microtuble arrays and wall microfibril orientation during in vitro cotton fiber development. Journal of Cell Science 101, 561–577.CrossRefGoogle Scholar
Shirley, B. W. (1996). Flavonoid biosynthesis: new function for an old pathway. Trends in Plant Science 1, 377–388.Google Scholar
Soomro, Z. A., Kumbhar, M. B. & Larik, A. S. (2009). Heterosis and inbreeding depression for quality traits in diverse cotton genotypes. Journal of Agricultural Research 47, 349–358.Google Scholar
Srivastava, H. K. (2000). Nuclear control and mitochondrial transcript processing with relevance to cytoplasmic male sterility in higher plants. Current Science 79, 176–186.Google Scholar
Stapleton, A. E. & Walbot, V. (1994). Flavonoids can protect maize DNA from the induction of ultraviolet radiation damage. Plant Physiology 105, 881–889.CrossRefGoogle ScholarPubMed
Thaker, V. S., Rabadia, V. S. & Singh, Y. D. (1999). Physiological and biochemical changes associated with cotton fibre development. VII. Carbohydrate metabolism. Acta Physiologiae Planttarum 21, 57–61.CrossRefGoogle Scholar
Tokatlidis, I. S., Tsikrikoni, C., Lithourgidis, A. S., Tsialtas, J. T. & Tzantarmas, C. (2011). Intra-cultivar variation in cotton: response to single-plant yield selection at low density. Journal of Agricultural Science, Cambridge 149, 197–204.CrossRefGoogle Scholar
Tokatlidis, I. S., Tsikrikoni, C., Tsialtas, J. T., Lithourgidis, A. S. & Bebeli, P. J. (2008). Variability within cotton cultivars for yield, fibre quality and physiological traits. Journal of Agricultural Science, Cambridge 146, 483–490.CrossRefGoogle Scholar
Updegraff, D. M. (1969). Semimicro determination of cellulose in biological materials. Analytical Biochemistry 32, 420–424.CrossRefGoogle ScholarPubMed
Vreeland, J. M. Jr (1987). Colour cotton return to the native. International Development Research Centre Reports 10, 4–5.Google Scholar
Wang, G. Q., Xu, C. H. & Wei, J. M. (1999). Photosynthesis, respiration, and carbohydrate metabolism (in Chinese). In Manual of Modern Plant Physiology Experiments (Ed. , Z. C. Tang), pp. 96–97. Beijing, China: Science Press.Google Scholar
Wang, X. D., Dutt, Y. Y., Ni, X. Y., Zhao, X. Q. & Nirania, K. S. (2004). Breeding for semi-okra leaf hybrids in upland cotton (Gossypium hirsutum L.) (Abstract). In Proceedings of the International Symposium on Strategies for Sustainable Cotton Production: a Global Vision, held at UAS, Dharwad (Karnataka) from November 21–23, 2004 (Eds Khadi, B. M., Katageri, I. S., Patil, S. B., Vamadevaiah, H. M., Udikeri, S. & Eshanna, ), pp. 469. Dharwad, Karnataka, India: Socio Economics, University of Agricultural Sciences.Google Scholar
Wang, X. D. & Li, Y. Y. (2002 a). Development of cytoplasmic male-sterile, maintainer and restorer lines in colored cotton and construction of their DNA fingerprints. Journal of Zhejiang University (Agriculture & Life Sciences) 28, 1–6.Google Scholar
Wang, X. D. & Li, Y. Y. (2002 b). Study on characteristics of colored cotton fiber development. Journal of Zhejiang University (Agriculture & Life Sciences) 28, 237–242.Google Scholar
Wang, X. D. & Li, Y. Y. (2002 c). Study on extraction and quantification of fiber pigment matter in colored cotton. Journal of Zhejiang University (Agriculture & Life Sciences) 28, 596–600.Google Scholar
Wang, Y. H., Shu, H. M., Cheng, B. L., Mcgiffen, M. E. Jr, Zhang, W. J., Xu, N. Y. & Zhou, Z. G. (2009). The rate of cellulose increase is highly related to cotton fibre strength and is significantly determined by its genetic background and boll period temperature. Plant Growth Regulation 57, 203–209.CrossRefGoogle Scholar
Wilkins, T. A. & Jernstedt, J. A. (1999). Molecular genetics of developing cotton fibers. In Cotton Fibers: Developmental Biology, Quality Improvement, and Textile Processing (Ed. Basra, A. S.), pp. 231–269. New York: Food Products Press.Google Scholar
Wu, Y. T., Yin, J. M., Guo, W. Z., Zhu, X. F. & Zhang, T. Z. (2004). Heterosis performance of yield and fibre quality in F1 and F2 hybrids in upland cotton. Plant Breeding 123, 285–289.CrossRefGoogle Scholar
Yoshida, K., Kitahara, S., Ito, D. & Kondo, T. (2006). Ferric ions involved in the flower color development of the Himalayan blue poppy, Meconopsis grandis. Phytochemistry 67, 992–998.CrossRefGoogle ScholarPubMed
Yuan, S. N., Hua, S. J., Ni, M., Li, Y. Y., Wen, G. J., Shao, M. Y., Zhang, H. P., Zhu, S. J. & Wang, X. D. (2010). The relationship between fiber macroelement content and fiber quality in colored cotton. Scientia Agricultura Sinica 43, 4169–4175.Google Scholar
Zhang, W. J., Shu, H. M., Hu, H. B., Cheng, B. L., Wang, Y. H. & Zhou, Z. G. (2009). Genotypic differences in some physiological characteristics during the cotton fibre thickening and its influence on fibre strength. Acta Physiologiae Plantarum 31, 927–935.CrossRefGoogle Scholar
Zhang, X. Q., Wang, X. D., Jiang, P. D., Hua, S. J., Zhang, H. P. & Dutt, Y. (2007). Relationship between molecular marker heterozygosity and hybrid performance in intra- and interspecific hybrids of cotton. Plant Breeding 126, 385–391.CrossRefGoogle Scholar
Zhao, X. Q. & Wang, X. D. (2005). Study on heterosis and seed production of hybrid between cytoplasmic male sterile lines and restoring lines in colored cotton. Cotton Science 17, 8–11.Google Scholar
Zhu, W., Liu, K. & Wang, X. D. (2008). Heterosis in yield, fiber quality, and photosynthesis of okra leaf oriented hybrid cotton (Gossypium hirsutum L.). Euphytica 164, 283–291.CrossRefGoogle Scholar
Figure 0

Table 1.Plant genotypes used in present study

Figure 1

Table 2.Performance of cotton lines and heterosis for agronomic attributes in 2008 and 2009 in Hangzhou, China

Figure 2

Table 3.Performance of cotton lines and heterosis for yield and yield components in 2008 and 2009 in Hangzhou, China

Figure 3

Table 4.Performance of cotton lines and heterosis for fibre quality traits in 2008 and 2009 in Hangzhou, China

Figure 4

Table 5.Correlation coefficient (r) between cotton fibre quality and physiological attributes

Figure 5

Fig. 1.Dynamics of flavonoid concentration at different cotton fibre developmental stages (5, 10, 15, 20, 25, 30, 35 and 50) in interspecific hybrids (ZUC × ZUA and ZUF × ZUA), intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUC, ZUA, ZUF and ZUG). Bars in the histogram are standard errors.

Figure 6

Fig. 2.Dynamics of cellulose concentration at different cotton fibre developmental stages (15, 20, 25, 30, 35 and 50) in interspecific hybrids (ZUC × ZUA and ZUF × ZUA), intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUC, ZUA, ZUF and ZUG). Bars in the histogram are standard errors.

Figure 7

Fig. 3.Dynamics of pH value at different cotton fibre developmental stages (0, 5, 10, 15, 20, 25, 30 and 35) in interspecific hybrids (ZUC × ZUA and ZUF × ZUA), intraspecific hybrids (ZUC × ZUG and ZUF × ZUG) and their parents (ZUC, ZUA, ZUF and ZUG). Bars in the histogram are standard errors.

Figure 8

Table 6.Dynamic change of cotton fibre carbohydrate contents at different developmental stages of materials in 2009 Hangzhou, China