Mi. Chaudhary et K. Fujita, COMPARISON OF PHOSPHORUS DEFICIENCY EFFECTS ON THE GROWTH-PARAMETERS OF MASHBEAN, MUNGBEAN, AND SOYBEAN, Soil Science and Plant Nutrition, 44(1), 1998, pp. 19-30
Experiments were conducted in order to examine the inter-specific diff
erence in low P tolerance in terms of biomass production, photosynthet
ic rate per unit leaf area (Po) and biological nitrogen fixation (BNF)
. Three legume species: mashbean (Vigna aconitifolia cv. Mash-88), mun
gbean (Vigna radiata cv. Moong-6601), and soybean (Glycine max L. cv.
Tamahomare) were grown at different levels of P applied in 1993 and 19
94. Dry matter production increased in all the species with the increa
sing P levels. At low P levels up to 25 kg P ha(-1), soybean displayed
a relatively higher biomass production than mashbean and mungbean, wh
ich was mainly caused by the promotion of root growth and leaf area ex
pansion. In low P mashbean plants leaf area development was severely i
nhibited while Po remained relatively stable in all the species irresp
ective of the P levels except for extremely low Po at later growth sta
ges without application of P. A positive correlation between the amoun
t of N accumulation and acetylene reduction activity (ARA) was found i
n all the species (r=0.77). At low P levels, soybean absorbed a large
r P amount than other species and the amount of P absorbed was positiv
ely correlated with biomass production (r=0.99*). At low P levels, th
e P concentration decreased in all the plant parts and such a decrease
was pronounced in the nodules. These results suggest that soybean has
a higher tolerance under suboptimal conditions of P supply compared w
ith mashbean and mungbean, mainly due to a higher ability of leaf area
expansion and absorption activity of P through expansion of root inte
rception.