Abstract
A study was undertaken to find out the suitable dose of boron for three selected cropping patterns viz. mustard-boro rice-T. aman rice, wheat-mungbean-T. aman rice, and chickpea-T. aus rice-T. aman rice. The experiments were conducted in two locations under Rangpur district, OFRD farm (on-station) and FSRD site (farmer's field), during 1997-99 over two crop cycles for each pattern. Boron was applied to one, two or three crops in a pattern so as to evaluate the direct and residual effects of B application. Evaluation was made with respect to the yield & yield components, nutrient concentrations (N, P, K, S, Zn & B) and soil properties (pH, organic matter, total N and available P, K, S, Zn & B contents) for each cropping pattern. Four crops viz. mustard, wheat, mungbean and chickpea from the cropping pattern experiments responded significantly to boron application. The grain/seed yield was strongly correlated with the number of grains spike1 or seeds pod "'. Application of boron at 1 kg ha1 was adequate to overcome the B deficiency and to obtain satisfactory yield of the crops. Mungbean as a second crop did not need further supplement of boron when the first crop received this element at 1.5 kg ha'. Of the four crops, response of chickpea to added B was more pronounced than that of mustard or wheat or mungbean. Virtually there was no positive effect of added boron on the rice crops (boro, T. aus and T. aman rice). The crop yield was strongly correlated with nutrient uptake as influenced by boron application. Apparent nutrient balances for both N and K were negative and that for P, S, Zn or B was positive. Another study was carried out to evaluate the response of different varieties of mustard, wheat and chickpea to boron application. The varieties of a crop differed markedly in their response to added boron. The Brassica napus varieties (BARI sarisha-7 and BARI sarisha-8) were more sensitive to boron deficiency compared to B. juncea (Rai-5 and Jamalpur-1) and B. campestris (Improved Tori-7 and Kalyania) varieties. In case of wheat varieties, Kanchan compared to the others (Sonalika, Sourav, Gourav, Protiva and Agrahani) was found to be the most responsive to the added B. Comparing the performances of chickpea varieties (Nabin, BARI chola-2, BARI chola-3, BARI chola-4, BARI chola-5 and BARI chola-6), BARI chola-5 had the highest response to B application. It is inferred that the application of boron at 1-1.5 kg ha1 to rabi crops would be sufficient to meet the requirement of boron for 2-3 crops in a pattern.