Study On High Yield Mechanism Of Rice Under The Control Of Water And Fertilizer Coupling

In order to probe into the physiological characteristics,photosynthesis,fertilizer utilization efficiency,and yield composition factors of high yield of tropical rice.Three tests,namely,Control of Water and Fertilizer Coupling?CWF?,Moisture Single Factor Test?MFT?,and Nitrogen Fertilizer Level Test?NLT?under water-saving irrigation were conducted.The three irrigation modes of flooding irrigation,water-saving irrigation and water stress were used as the main factors in CWF,and fertilizer treatment was used as a secondary factor?pure N:0,70,140kg/hm²,P₂O₅:0,38,76kg/hm²;K₂O:0,54,108kg/hm².?for orthogonal test.Flooding irrigation?W1?,water-saving irrigation?W2?and water stress?W3?were chosen as the three water treatment modes in MFT;NLT?pure N:0,55,110,165kg/hm² was respectively marked as:N₀,N₁,N₂,N₃;P₂O₅:38kg/hm²,K₂O:54kg/hm²?.The test results demonstrated that:1.The rice yield was significantly increased by CWF,and the number of effective panicles was significantly increased by the sufficient water and fertilizer,but the1000-grain weight was lower.The maximum yield of N₂P₁K₁ was 7,671kg/hm²in flooding irrigation.The study showed that there was synergy between water and fertilizer,and fertilization under drought condition could alleviate the pressure of water stress to a certain extent;the content of soluble protein and soluble sugar was increased with the increase in fertilizer application under sufficient water condition.The photosynthetic capacity of rice was improved by water-fertilizer coupling.The results showed that chlorophyll increased with the increase in fertilizing amount,and the stomatal conductance?Gs?and net photosynthetic rate?Pn?of rice leaf were the highest under flooding and water-saving irrigation with N₂P₁K₁.2.The results of the moisture test showed that the yield was respectively increased by43.7%and 32.15%at flooding and water-saving irrigation,compared with drought,and water consumption by flooding was 1.12 times that of water-saving irrigation.With the increase of water stress intensity,the contents of soluble protein,soluble sugar,proline and the activity of peroxidase were increased.During the growth period,the contents of soluble sugar and soluble protein were firstly increased and then decreased.Proline were sustained accumulation increased,peroxidase activity were increased firstly and then decreased.In flooding at the tillering and full heading stages in the drought at mature period,the root activity was weakest,but it was increased from the tillering stage to the mature stage.The photosynthetic rate,stomatal conductance,intercellular CO₂ concentration and transpiration rate was significantly reduced by drought stress.The content of chlorophyll a,chlorophyll b and total chlorophyll was gradually decreased in the growth period,and such content at drought and water-saving irrigation was greater than that at flooding irrigation;The study on agronomic characters and yield of rice showed that:the tiller number,leaf area,plant dry weight,number of effective panicles,kernels per spike,thousand kernel weight,setting percentage and yield were increased by water-saving irrigation.Different moisture treatment significantly affected the accumulation in different organs,of which water-saving irrigation improved the accumulation of nitrogen,phosphorus and potassium in rice stem,leaf,root and spike in each stage;in the whole growth period,the accumulation of nitrogen and potassium in stem leaf increased at first and then decreased,and the accumulation of phosphorus remained stable after gradual increase.The accumulation of nitrogen and phosphorus in root was increased after decrease at first,while the potassium accumulation showed a decreasing trend.The accumulation of nitrogen and phosphorus in spike in full heading stage was higher than that in the mature period,while the accumulation of potassium in such two stages just showed slight difference.3.The NLT in rice field indicated that,the application of pure N fertilizer?110 kg/hm²?had the best yield-increasing effect.The number of effective spikes and kernel number per spike were positively correlated with the nitrogen application rate,while the thousand kernel weight and seed setting rate was negatively correlated with the nitrogen application rate.From the perspective of substance accumulation,the increase in nitrogen application rate could increase the accumulation of nitrogen,phosphorus and potassium in rice stem,leaf and spike.N₃ showed the highest nitrogen utilization efficiency,N₀ had the maximum nitrogen harvest index,and N₂ treatment showed the higher nitrogen agronomy efficiency.4.The conductivity was significantly influenced by different moisture treatments,and the soil conductivity could be increased with the increase in irrigation moisture;in addition,the correlation analysis showed that the conductivity had a significant negative correlation with soil available potassium,but had a significant positive correlation with the accumulation of nitrogen and phosphorus in root and the total phosphorus accumulation in plant;the conductivity was positively correlated with the yield,plant dry weight,and flag leaf length/width,but negatively correlated with the total chlorophyll.