To find out the responses of soybean genotypes in terms of different levels of irrigation with the aim of evaluating the growth, yield, and its optimum levels of irrigation, an experiment was conducted at the Field of Crop Botany Department, Bangladesh Agricultural University, Mymensingh during the period from November 2000 to February 2001. Five levels of irrigation viz. ~textrmI0 : no irrigation, ~textrmI1 : one time irrigation at 20 days after sowing (DAS), ~textrmI2 :two times irrigation at 20 and 40 DAS, ~textrmI3 : three times irrigation at 20, 40, and 60 DAS, and ~textrmI4 : four times irrigation at 20, 40, 60, and 80 DAS and three genotypes of soybean viz. BS-3, BS-16, and BS-60 were used in this experiment. The crop was grown in a split plot design having three replications. The plant height, leaf area index, crop growth rate, shoot dry weight, branches ~textrmplantI-1 , filled pods ~textrmplantI-1 , seeds ~textrmplantI-1 , seed yield, and harvest index were influenced significantly by irrigation and these were found to be highest at three times irrigation except branches ~textrmplantI-1 . The chlorophyll content increased but empty pods ~textrmplantI-1 decreased with increase in irrigation levels. Genotypes of soybean varied significantly in terms of growth attributes at various growth stages except shoot dry weight at 90 DAS. The genotype BS-3 performed better compared to other genotypes and gave maximum seed yield.

Blackgram (Vigna mungo) is more salt tolerant than mungbean (Vigna radiata). This study was initiated to know whether the accumulation pattern of mineral ions in different plant parts plays a significant role in the differences in salt tolerance between the two Vigna species. Different mineral ions, viz. N, Cl, Na, K, Mg and Ca in different organs of two varieties of each of blackgram- Barimash-l (susceptible one) and Barimash-2 (tolerant one), and mungbean-Barimung-3 (tolerant one) and Barimung-4(susceptible one), were analyzed after growing with 0, 50, 75 and 100 mM NaCl solutions. The two crops showed a decreased but similar pattern of total N accumulation under saline conditions. The tolerant variety of both the crops showed a less reduction in total N than the susceptible one. Leaves showed the maximum while stem the minimum N, irrespective of levels of salinity. C l[-10] and N a+ accumulation increased with the increasing salinity levels. Interestingly, similar to a halophyte, the salt tolerant blackgram exhibited conspicuously higher amount of N a+ in the shoot than the salt-susceptible mungbean. However, the tolerant varieties showed less amount of N a+ than the susceptible one, especially in blackgram. Seeds of both Vigna spp. accumulated the minimum amount of N a+ than other plant parts. K+ accumulation decreased by salinity in most of the plant parts, except seeds. Blackgram showed larger reduction in K than mungbean. The Mg++ increased in leaves, petioles and stem by salinity while decreased in the roots, podshells and seeds in both the crops. Salinity increased Ca++ accumulation in all plant-parts except roots of both Vigna spp. Apparently, the leaves of mungbean accumulated higher concentration of Ca++ than blackgram. Varietal differences in the accumulation pattern of K+ , Mg++ and Ca++ were not clear. It was concluded that blackgram, presumably, possesses a similar salt tolerance mechanism to halophyte, and the pattern of accumulation of mineral ions in blackgram and mungbean was not fully ascribed to the differences in salinity tolerance between the two Vigna species.gna species.ies.s.ies.

Dry matter(DM) accumulation in different plant parts of two Vigna spp., blackgram(Vigna mungo) and mungbean(Vigna radiata), was compared at different levels of salinity. Two vaarieties of each of blackgram (Barimash-1 and Barimash-2) and mungbean(Barimung-3 and Barimung-4) were grown with 50, 75 and 100mM NaCl solutions and tap water as a control till maturity. The DM accumulation in all plant parts of the two crops devreased with the increasing salinity levels. The reducation was severe in mungbean compared to blackgram. On an average mungbean produced only 3% grain yield compared to 37% in blackgram at 100mM NaCl. The salinity induced growth reduction was relatively less in Barimash-2 than that in Barimash-1. In mungbean, the relative DM production of Barimung-3 was greater than Barimung-4. The extent of biomass reducation due to salinity in different plant parts was not similar. At maturity the rank of biomass accumulation (at 100 mM NaCl) in different plant parts of blackgram was in decreasing order by seeds pod-1 (97%), branch plant-1 (88%), 1000-grain weight (79%), plant height(72%), pods plant-1 (50%), leaf weight and root mass(both 49%) and stem weight (48%). In mungbean, the rank was in decreasing order by 1000-grain weight (57%), leaf weight (54%), plant height (52%), seeds pod-1 (50%), branch plant-1 (41%), root weight (34%), stem weight (24%) and pods plant-1 (6%). Therefore, salinity reduced grain yield more than straw and roots of the Vignaq spp., and blackgram is relatively more salt-tolerant than mungbean.