Exogenous application of 6-BA and GA3 collaboratively improves cottonseed yield and seed quality via altering production of carbohydrates in the embryo

Abstract

ABSTRACT Cottonseed produces oil for human consumption and protein meals for ruminant feed, and carbohydrate metabolism takes responsibility for seed oil and protein biosynthesis. Here, 6-BA and GA3 were evaluated by seed or foliar application for its effect on physiological and productive parameters of cottonseed in two-year field experiment. Results showed that 6-BA and GA3 significantly enhanced cottonseed yield because of increased boll number and seed index. Boll number was the dominant driver of yield increment for seed priming with 6-BA, and the increase was greater than GA3, resulting in higher yield for seed priming with 6-BA (18.8–20.1%) than with GA3 (10.7–14.5%) while the increase in yield was statistically at par between spraying of 6-BA and GA3. Although seed coat weight was not affected by 6-BA and GA3, embryo weight, oil and carbohydrate content were significantly increased by any given treatments. Higher carbohydrate content was attributed to increased sucrose, hexose and starch contents, which were closely associated with higher sucrose synthase, acid invertase, and sucrose phosphate synthase activities. Moreover, increases in the activities of these sucrose metabolism enzymes were larger for seed priming with 6-BA than GA3, accounting for the difference observed in sucrose content between 6-BA and GA3 seed application.