Jvdkk. Rao et al., NITROGEN REQUIREMENTS AT DIFFERENT GROWTH-STAGES OF SHORT-DURATION PIGEONPEA (CAJANUS-CAJAN L MILLSP), Journal of agronomy and crop science, 175(1), 1995, pp. 15-28
The response to N fertilization of a short-duration pigeonpea genotype
, ICPL 87, was studied in the field to assess the scope for geneticall
y improving symbiotic N-2 fixation by pigeonpea. The field study was u
ndertaken during 1985, 1986 and 1987 growing seasons on Vertisol and A
lfisol at ICRISAT Center (peninsular India), Inceptisol at Gwalior (ce
ntral India) and Entisol at Hisar (northern India) in as non-limiting
environmental conditions as possible. Nitrogen fertilizer was applied
to the soil at various growth stages to determine when N becomes most
limiting. There was a significant response in grain yield to fertilize
r N applied at flowering in Vertisol but not in Alfisol, Inceptisol or
Entisol. This suggests that biological N-2 fixation by short-duration
pigeonpea was not adequate to meet N requirements of the crop grown i
n Vertisol but that it was probably adequate in the other three soil t
ypes. These results are discussed in relation to the nodulation and ac
etylene reductase activity of pigeonpea and also N mineralization pote
ntial of different soils. It can be concluded that there is a need for
genetic improvement of N-2 fixing ability of short-duration pigeonpea
grown on heavy textured soils such as Vertisols.