PJB-2019-334
EARLIER PACLOBUTRAZOL APPLICATION IMPROVES PEANUT YIELD AND QUALITY BY SUPPRESSING EXCESSIVE GROWTH
JIALEI ZHANG
Abstract
Peanut plants frequently show excessive vegetative growth in high fertility loamy soils, which causes excessive growth and then lead to low pod yield. We hypothesized that optimum time of paclobutrazol application might be better control the allocation of assimilates to reproductive growth, and have the higher seed yield. In this study, 2-year field experiments were conducted to evaluate the effects of paclobutrazol on peanuts morphology, physiology, pod yield and seed quality at different growth stages. Paclobutrazol was sprayed on foliage at a concentration of 100 ppm when plant height reached 0.25 m (PBZ-1), 0.30 m (PBZ-2) or 0.35 m (PBZ-3). The results showed that paclobutrazol application significantly reduced plant height and number of nodes on the main stem and increased branch number. Compared with other treatments, PBZ-1 treatment significantly enhanced chlorophyll content, net photosynthesis rate and antioxidant enzymes activity in leaves, but significantly reduced the concentration of gibberellins (GA3) and indole-3-acetic acid (IAA) hormones, which are positively related to plant height and number of stem nodes. However, the treatment significantly increased zeatin riboside (ZR) and abscisic acid (ABA) concentrations, which are positively related to branch number. Paclobutrazol application significantly improved pod yield and seed quality, including the increases in fat, oleic acid and O/L ratio (oleic acid/linoleic acid), and the decreases in protein, total amino acid and linoleic acid contents. The results suggested that PBZ-1 treatment was the optimal application time for controlling large-seed peanut plant excessive growth and increasing pod yield in high fertility loam, which indicate that peanut plants grown in high fertility soils can be successfully treated with paclobutrazol at early vegetative growth stage to inhibit aboveground growth and promote reproductive growth.
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