Effect of excess boron supply on accumulation of boron and nitrogen metabolism in groundnut plants

Abstract

In both soil and sand cultures, a supply of 10 ppm boron to root medium was highly injurious to the groundnut (TMV-2) plants. The boron-treated plants grown it sand cultures absorbed relatively much higher quantities of boron and the foliage manifested chlorosis (yellowing) more quickly than in the boron-treated plants raised in soil cultures. In sand cultures, on the ninth day after boron treatment, the basal, mature middle and apical developing leaves accumulated excessive boron contents (2·51, 2·86 and 2·62 mg/g on oven-dry weight, respectively) and turned severely chlorotic; roots, stems and petioles also contained more boron content but much less than in the leaves; the chlorotic leaves were associated with decrease in total N and protein N and with considerable increase in soluble N; the contents of free amino-acids aspartic acid, glutamic acid, arginine, glycine and alanine were markedly enhanced when compared to the control plants.