DRY MATTER ACCUMULATION AND PARTITIONING IN VARIOUS FRACTIONS OF COTTON BOLLS

Abstract

SUMMARYThe distribution of dry matter among the fractions of cotton boll (the bur, the fibre and the seed) may have significant impact on fibre biomass per boll, and consequently on lint yield. Little is known on how cotton boll allocates available photosynthetic assimilates to its components. A two-year field study was conducted to ascertain the difference in boll dry matter production and partitioning among three cotton genotypes differing in boll size and lint percentage. The dynamics of dry matter production in all fractions of cotton boll against boll age followed a logistic pattern. The final dry weights of all components were largely due to the duration of dry matter exponential accumulation, and less correlated with the maximal rate of exponential accumulation. Partitioning biomass to the bur differed significantly among these genotypes at 10 days post-anthesis (DPA). The genotypic difference in partitioning biomass to the fibre was originally observed at 24 DPA in 2009, while in 2010, this was observed at 17 DPA. The genotypic difference emerged rather late for the seed ratio compared with the fibre ratio and the bur ratio, which was first observed at 45 DPA in 2009 and at 31 DPA in 2010. These results indicate that management practices may need to be applied to cotton plants prior to 31 DPA to ensure optimal boll size and partitioning. Large boll genotype MM-2 consistently maintained higher seed ratio and lower fibre ratio than two other genotypes (2870 and AX) due to more developing ovules in its boll. These differences contributed to significant difference in lint percentage and less difference in fibre mass per boll between MM-2 and 2870 and AX.