N/P Absorption and Accumulation and N Nutrition of Hybrid Rice

Using Teyou 63, the absorption and accumulation characteristics of N and K, as well as the N nutrition of the hybrid rice were studied. The results showed that there was a linear correlation between the total nutrient absorption and accumulation of N, and K2O and the square root of fertilizer application rate. With the increased fertilizer application rate, the nutrient uptake also increased. However, the nutrient utilization efficiency was reduced. Before the rice-heading started, the N accumulation centers were in the leaves and stem-sheath. After the heading, the center moved to the ears. After the heading, about 55% of N in the leaves and about 40% of N in the stem-sheath transported to the ears. The apparent transporting rate of the grain-filling was about 90%. The K accumulation centers were in the stems and sheaths, storing about 70% of K for the entire plant. After the heading, 34% to 40% of the K transported into the ears and the stem-sheath, with an apparent transporting rate of about 80%. In high yield cultivation, the highest N and K2O application rates were 2 kg and 2.72 kg, respectively, for every 100 kg of grain yield. The economic N and K2O application rates were 1.75 kg and 1.25 kg, respectively. The hybrid rice was more sensitive to N fertilization, and more resistant to low or high K than the other nutrients. The highest N application rate and economic K application rate should be recommended for the rice production. During each growth period, the leaf dry matter weight increased with N application. At the tillering stage and bud differentiation stage, the dry matter weight of stem-sheath also increased with N application. But from meiosis, both the stem-sheath weight and ear weight had parabolic correlation with N application. Therefore, the N nutrition was further studied. The N content in the leaves of high yield rice at different growth and development phases of the hybrid rice was determined. Each growth period and leaf positions at different N application rates had a certain color level and color difference among them, which provided an index for the N nutrition diagnosis.