Influence of time and level of nitrogen application of growth and yield of rice

Summary Results of a greenhouse sand-culture experiment conducted to study the effect of increasing or decreasing nitrogen supply at various stages of growth on the growth, yield, and yield components of rice are reported. Adequate nitrogen during the vegetative phase of growth encouraged tillering which had a bearing on the number of panicles per plant. Excess nitrogen during the reproductive phase of growth produced panicles with unfilled or partly filled grains. Similar effects were observed when the nitrogen status of the growth medium was changed from a low to a high level at the stages of reduction division and anthesis. Decrease in yield was observed when plants growing at a low level of nitrogen were transferred to a high level at the end of the vegetative phase. High levels of nitrogen in the growth medium at time of heading and after increased the concentration of nitrogen in the grain. There was an inverse relationship between yield of filled grain and nitrogen in the grain.     

Magnesium-sodium interactions effecting the uptake and distribution of potassium and calcium by cotton

Summary Significant Mg — Na interactions were found to govern the uptake and distribution of potassium and calcium by cotton. Contrary to the generally accepted views of cation antagonisms, it was found that under certain conditions sodium increased the potassium and calcium contents of plants. The effect of sodium was even more pronounced when magnesium was limiting.     

Evaluation of the nitrogen nutrition status of rice by plant analysis

Summary The results of a greenhouse and a field experiment to evaluate the nitrogen nutrition status of rice indicate that: (1) first and second most recently natured leaves are sensitive indicators of the nitrogen status of plants; (2) the total nitrogen concentration in these leaves are a better indicator of the nutrient status of plants than are the water-soluble and amide-plus-ammonium nitrogen fractions; and (3) that the best correlation between plant growth and total nitrogen is obtained when these leaves are sampled at the stage of growth between maximum tillering and panicle emergence.