Effects Of Nutrient And Water Management On Eco-physiological Of Rice (Oryza Sativa L.)

The experiments were carried out in the experiment station of China National Rice Research Institute(30゜05'N,119゜56'E) during 2006—2007 to study the physiological and ecological effects of nutrient and water management on rice.Using the typical rice varieties in the field and tanks,a series of research were conduct to study the effects on oxidation-reduction potential in root zones,tillering dynamics, leaf area index,nitrogen accumulation, yield under different nutrient and water managements. The main results were as follows:On the rice regreening stage, the Eh value of rhizosphere was significantly lower in the early period after the application of organic fertilizer, and the more organic fertilizer, the lower the Eh was. The Eh was significantly lower in the submergence than in the aerobic irrigation for the whole period. The result shows that under the condition of strong reducing, leaf area index, nitrogen accumulation were all influenced significantly. The above-ground biomass decrease, Leaf Area cut down, Chlorophyll in rice leaf was decomposed faster than synthesis, and the leaf chlorophyll content was reduced. Under strong reducing, the elongation growth of rice were inhibited, and plant height were reducted.The effects of the different fertilizer and water management on the actinomycetes showed that the organic N fertilizer rate was higher, the number of actinomycetes was more.The result implied that there had significant differences among variyies. Under the same water condition, the higher the organic N fertilizer rate was, the more the number of actinomycetes in the aerobic irrigation.Under the same rate of nitrogen, (which was 205kg/hm2), the effect of organic and inorganic N fertilizer on dry matter was studied. The experiment result showed that the organic N fertilizer rate was higher,the dry matter weight was lower under the combined application of organic fertilizer and inorganic fertilizer.When the ratio of orginc N to chemical N was 1∶3, the biomass of rice plant in the growth period was the largest,while leaf senescence faster than other treatnents. To some extent, the higher the orginc N rate was, the lower the apparent export percentage of stem and sheath had, and the higher the apparent export percentage of leaf had. The experiment result also showed that the treatment which the rate of organic N fertilizer was higher, has more grains per panicle and lower seed setting rate. The grain yield was the highest when the ratio of orginc N to chemical N was 1∶1.The effects of water management on rice growth and ecological characteristics showed that the leaves biomass in the submergence is more than that in the aerobic irrigation at rice growth period, while the leaves biomass at filling stage were just contrary to the growth period. Different rice varieties have different responses to water. Leaf area index in the aerobic treatment is larger than that in the submergence treatment. It was beneficial to photosynthetic matter accumulation in the aerobic treatment, The treatment in the submergence decrease the the apparent export percentage of stem and sheath。For the apparent export percentage of leaf, different fertilization managements have different responses to water. The number per spike and the seed-set rate were significantly imprived in the aerobic,thus it increase yield by 2.5%-10%.The rice nitrogen uptake under different fertilizer and water management was carried out.The result showed that the organic N fertilizer rate was higher, the nitrogen content of leaves, stem and sheath peer plant had higher.while the total nitrogen of stem and sheath was opposite. For the fertilizer use efficiency, the rate organic fertilizer was higher, the nitrogen use efficiency was lower. When the ratio of organic N to chemical N was 1∶1, harvest index, N harvest index, nitrogen partial factor productivity were the largest.The effects of nitrogen fertilizer on biomass accumulation and distribution in rice showed that the effect of nitrogen application amount on upland dry matter weight was remarkable. At filling period, . Stem weight of rice took on a firstly increasing and second decreasing and then increasing change, it impiied nutrient content repeated accumulated in rice stem.The relative contents of dry matter by transferred to shoots were in the lowest under low nitrogen treatment. With the increase of nitrogen rate, dry matter accelerated significantly.The increase of spike dry weight depended on a great extent on photosynthesis at filling stage. Nitrogen accumulation in spike depended on the nitrogen accumulation of leaves, stem and sheat before flowering, the nitrogen accumulation of leaves during filling stage occupied very little percentage of spike nitrogen content.Translocation of Assimilates was affected by panicle fertilizer, and the proportion panicle fertilizer was higher, the inhibition was stronger.It implied that it was the important factor to control the amounts of spike fertilizer under high rates of N utilization.