Effects of Paclobutrazol on Podding and Photosynthetic Characteristics in Peanut
Sachiko Senoo and Akihiro Isoda

(Faculty of Horticulture, Chiba University, Matsudo, Chiba 271-8510, Japan)

Abstract
The effects of paclobutrazol on podding habits and photosynthetic characteristics (CO2 assimilation rate, quantum yield of photosystem II (É≥PSII) and chlorophyll content) were examined in peanut. The paclobutrazol treatment at the beginning of the pod formation stage increased the percentage of podding, particularly by early-blooming flowers, leading to an increase in seed yield. The major factor for this effect may have been an acceleration of dry matter distribution to the early bearing pods with inhibition of stem growth by the paclobutrazol treatment. The paclobutrazol treatment at the early pod formation stage increased chlorophyll content andÉ≥PSII, resulting in enhanced CO2 assimilation rates. In the long term, crop growth rate and net assimilation rate tended to have increased after the paclobutrazol application, although these effects were not significant. The effects of the paclobutrazol treatment on the photosynthetic characteristics, however, were efficacious just during a rather short period at a proper growing stage, suggesting that increased efficiencies of the photosynthetic characteristics would not be the main factor for increasing seed yield.