Effects Of Water And Fertilizer Interaction On Growth, Yield And Quality Of Rice

Rice Liangyoupeijiu and Yangliangyou 6 hao were chosen to do experiments separately in plastic greenhouse's pot in Huazhong Agriculture University and in the fields in Junchuan, Suizhou. Set different soil water potential, irrigation condition and nitrogen level to study the effect of water and fertilizer interaction on rice growth and physiology characters, nutrient absorption situation, yield and quality. The results show:1. The effects on rice growth status: the tillers, plant height, per plant leaf area, each part of plant of the rice are influenced by nitrogen fertilizer obviously, and raise by the increase of nitrogen rate, but irrigation condition has little influence on tillers and plant height. Conclusively, nitrogen increasing tend can improve the group growth quality. However, too much nitrogen is not beneficial to the growth of rice. In plastic greenhouse's pot, if over 2.5g nitrogen is used in each pot (equivalent to 375kg/hm2 in fields), and the soil water potential is lower than -30kPa, serious water stress phenomenon will appear, rice growth period will delay obviously, and plant height, per plant leaf area and dry weight of plant's every part will decrease inversely.2.The effect on rice physiology: under different irrigation treatments the leaf SPAD value increases with the nitrogen rate increases in each growth period, Under low nitrogen level SPAD value turn to lower from tillering stage to booting stage and from heading stage process to increase.Water stress inhibits rice's absorption of nitrogen, thus rice's leaf SPAD value decreases. Under pot condition, except that flooding irrigation bleeding intensity improves with the nitrogen rate increases, in other water conditions under different nitrogen rate the differences of bleeding intensity are not obvious. Generally the MDA content in leaf first decreases and then increases as the improvement of nitrogen rate. When the nitrogen rate is low, under the same nitrogen level but different water conditions, the differences of MDA content are not obvious. However, when the nitrogen level is high(N4, N5), rice's leaf MDA content is influenced by water condition obviously, and the content is higher when the rice is in flooding irrigation and serious dry stress, which shows that rice leaves get old obviously in the adversities above.3. The effects of Water-Fertilizer interaction on the dry matter contents and nutrient accumulation of rice: rice's dry matter quantity also increase as the increase of nitrogen rate, and it shows that the period between booting and full heading stage dry matter quantities accumulate slowly. The accumulation of nitrogen and phosphorus in rice are similar with day matter, and they increase with the nitrogen rate's improvement. Potassium content is low as the nitrogen rate is high, and lodging resistance ability is also poor.4. The effects of Water-Fertilizer interaction on the yield and quality of rice: When the soil fertility is low, the increase of nitrogen rate can improve the grains, effective panicles, ear length, first panicle branch, seed setting rate and 1000-grain weight of rice, and makes increasing yield. For example, when soil water potential is -30kPa and in the level of N5 the yield decreases by 23.9% comparing with the level of N4.When in the condition of N2 and the soil water potential is 0kPa, the yield is the highest and higher than 6% of flooding irrigation. When soil water potential is-30kPa and-60kPa, the rice yield decreases by 28% and 37% comparing with the flooding irrigation. The effects on quality shows that under the same irritation condition the protein contents increase as the nitrogen rates increase, which shows that high nitrogen rate provides rich nitrogen source for the absorption of nitrogen and the synthesis of protein, but under the same nitrogen rate, the differences of different water conditions are not obvious. The amylose contents under each irrigation treatment reduce as the nitrogen rates increase, but under the same nitrogen rate, the differences of different irrigation treatments are not obvious.