Relationship between water content and growth of seed and fibre of three cotton genotypes

Three cotton genotypes (varying in their final seed size), viz. H-6 and H-4 (Gossypium hirsutum L.) and V-797 (Gossypium herbaceum L.) were studied for their growth kinetics of seed and fibre. Both biphasic linear and polynomial models were used to demark different phases of cotton seed growth. The polynomial model appeared to be appropriate to define the growth phases of cotton seed as compared to the linear model. The rate and the duration of dry matter accumulation were obtained by differentiating the best-fit polynomial equations. Based on the data of dry weight and water content, cotton seed development is divided into four different phases, viz. (a) cell division, (b) cell elongation, (c) dry matter accumulation and (d) maturation. The rate of dry matter accumulation showed a close correlation with water content of seed as well as of the fibre, in all three genotypes studied. It is proposed that water content of seed or fibre plays an important role in determining dry weight of three genotypes.