Black gram is one of the most important pulse crops in India because of its low cost and high quality protein. They play a major role in providing a balanced protein component in the diet of the people. Pulses contain a higher level of quality protein, nearly three times as much as cereals; therefore they are the cheapest and rich source of protein and essential amino acids and thus share a major protein of the vegetarian diet. Besides, the crops enrich the soil fertility and health in terms of addition of nitrogen and organic matter. Among pulses, black gram (Vigna mungo L. Hepper), occupies a unique place for its use as vegetable, and it is grown both as pure and mixed crop along with maize, cotton, sorghum and other millets. It is also known as urd bean, and it is an important pulse crop grown all over the world. It is a major component of the daily Indian diet and serves as a rich protein source (23.9%) besides; it also contains 60.4% carbohydrates. As per the World Health Organization every man needs 80 g of pulses per day and as per the Indian Council of Medical Research, every man needs minimum consumption of 47 g of protein per day to meet requirement of the body. But at present, the per capita availability of pulses is only 30~35 g per day. Therefore, there is a need for three fold increase in pulse production as that of current production. Black gram is indeterminate in its flowering and fruiting habits and there is a competition for available assimilates between vegetative and reproductive sinks. There is limitation of source (leaves) particularly at flowering and fruiting stage. Hence, there is a need to improve leaf nutrient content for growth and productivity of balck gram. Being a C₃ plant, nutrient content in leaf are relatively less than cereals and the major yield components are pods per plant, seeds per plant and test weight of seeds. Apart from this genetic makeup, the major physiological constraints limiting its production are flower drop and fruit drop (Ojeaga and Ojehomon, 1972).This performance of the crops can be overcome by foliar application of growth regulating chemicals at the crucial stages of the crop, which is one of the latest trends in agriculture. The growth regulating chemicals bioregulators can improve the plant nutrient content and play a significant role in improving the productive potential of the crop. With this above background, the present investigation was carried out.

Result

Total nitrogen content (N) (%)

The Nitrogen (N) content was significantly influenced by the treatments at all the growth stages (Table 1). The N content at various stages of crop growth viz., vegetative (30 DAS), flowering (45 DAS), pod filling (60 DAS) and harvest stages ranged from 1.06% to 2.24 %, 1.86% to 2.84%, 1.62 to 2.06% and 0.74 to 1.12% respectively. The treatment T₇ (N 25 kg/ha+ urea 2% + 0.1 ppm BR) measured higher N content of 2.24%, 2.84%, 2.06% and 1.12% at vegetative, flowering, pod filling and harvest stages, respectively.

Table 1 Effect of nitrogen nutrition and growth regulators on nitrogen content (%) in black gram at different growth stages

Total phosphorus content (P) (%)

The data presented in Table 2 revealed significant variations in the phosphorus (P) content of black gram CO 5 due to the various treatments imposed. The P content had increased up to flowering stage (45 DAS) and thereafter it declined till harvest. The P content at various growth stages viz., vegetative (30 DAS), flowering (45 DAS), pod filling (60 DAS) and harvest stages, ranged from 0.25 to 0.37%, 0.25 to 0.41%, 0.23 to 0.29% and 0.14 to 0.22%, respectively. The treatment T₇ (N 25 kg/ha+urea 2%+0.1 ppm BR) recorded the highest P content of 0.37%, 0.41%, 0.29% and 0.22% at vegetative, flowering, pod filling and harvest stages, respectively.

Table 2 Effect of nitrogen nutrition and growth regulators on Phosphorus content (%) in black gram at different growth stages

Total potassium content (K) (%)

The data onpotassium (K) content of black gram variety CO 5 as influenced by the nutrients and plant growth regulators at various growth stages is presented in Table 3. The treatment T₇ (N 25 kg/ha+urea 2%+0.1 ppm BR) recorded the highest P content at vegetative (1.59%), reproductive (2.47%), pod filling (1.48%) and harvest stages (1.09 %), respectively. Minimum contents of 0.78%, 1.29%, 1.01% and 0.84 % were for the treatment T₁ (control) recorded lower values at all crop growth stages.

Table 3 Effect of nitrogen nutrition and growth regulators on Potassium content (%)in black gram at different growth stages

Srivastava G.P., and V.C. Srivastava, 1994, Effect of irrigation and foliar spray of nutrients on growth and yield of greengram, Indian. J. agric. Sci., 64: 219-222