Suitable Water Storage In The Field After Raining For The Middle Rice At Tillering Stage

In order to make full use of the rainfall resources and reduce the loss of nitrogen and phosphorus caused by the drainage immediately after the rainfall,rice transplanted by transplanter and direct-seeding rice were as study objective,the experiment of different water storage depth and duration was designed after tillering fertilizer was applied,so as to understand the effects of phosphorus loss and yield,and to explore the suitable water storage depth and duration of organic rice and direct-seeding rice at tillering stage.The results show that:Firstly,with the increase of water storage depth and water storage time,the plant height showed a rapid growth of 20 days.After 20 days,the plant height showed a slow growth.The growth condition of plant height was the best under the condition of water storage of 6 cm for 3 days,and that of direct-seeding rice was the best under the condition of water storage of 8 cm for 3 days.With the increase of water storage depth and time,the peak value of tillering decreased,which inhibited the tillering of rice.The highest tillering peak was found in the condition of water storage for 6 cm for 3 days,and that of CK was the highest.The growth of water storage depth and duration inhibits the further growth of rice root system to soil depth.The inhibition of growth in rice 10-20 cm root system had the greatest effect,followed by 5-10 cm rice root system,which had little effect on the growth of 0-5 cm rice root system.Secondly,with the increase of water storage depth and time,the photosynthetic rate decreased and photosynthesis decreased.The photosynthetic rate was the highest under the condition of water storage of 6 cm for 3 days,and that of direct seeding rice was the highest under the condition of water storage of 8 cm for 3 days.With the increase of water storage depth and time,SPAD value and chlorophyll content of the phase decreased.The SPAD value was the highest under the condition of water storage of 6 cm for 3 days,and the photosynthetic rate of CK was the highest.Thirdly,when the rainfall is 80 mm,the total nitrogen,ammonium nitrogen,nitrate nitrogen and total phosphorus loss of CK is the highest,followed by T1,T4,the total nitrogen and ammonium nitrogen loss is the lowest.When the rainfall of direct seeding rice is only 50 mm,the water storage test will be carried out.Because the rainfall is low and the design water level is high,except for CK,irrigation is required to reach the design water level.Therefore,the deeper the water storage depth is,the more the drainage will be,and the greater the loss of nutrients will be finally led to.At the same water storage depth,the water storage will last for 7 days.the concentration of N and P in paddy field was lower than that of water storage for 3 days,so the loss of TN and NH 4-N T2 was lower than T1,T4 was lower than T3,T6 was lower than T5.Fourthly,the effective panicle,1000 grain weight,seed setting rate,number of grains per panicle and yield of rice under the condition of T1 water storage were the highest,which increased by 386 kg/hm~2,compared with CK;the other treatments showed the phenomenon of yield reduction compared with CK,T2,T3,T4,T5 and T6 decreased390.33 kg/hm~2(4.05%),195.67 kg/hm~2(2.03%),706.33 kg/hm~2(7.32%),1028.33kg/hm2(10.66%),1379.33 kg/hm~2(14.30%)respectively?Compared with CK,the yield of T1,T2,T3,T4,T5 and T6 decreased 247.64 kg/hm~2(2.58%),775.24 kg/hm~2(8.01%),633.33 kg/hm~2(6.99%),988.57 kg/hm~2(10.29%),1314.28 kg/hm~2(13.68%)and 1723.81kg/hm~2(17.94%).By analysis of experimental results obtained by phosphorus loss and yield,the following preliminary conclusions can be made:Firstly,If the effect of different water storage conditions on rice growth,yield and its factors is only considered,it is suggested that the depth and time of water storage in tillering period should be 6 cm,lasting for 3 days.If the yield and loss of nitrogen and phosphorus are considered comprehensively,the depth of water storage should be 9 cm,lasting for 3 days d.If it focuses on reducing the loss of nitrogen and phosphorus caused by drainage after rainfall,it is recommended that the storage depth be 9 cm,but the duration be 7 days.Secondly,When the rainfall is higher than the depth of water storage,if only considering the influence of different water storage conditions on rice growth,yield and its factors,it is suggested that the depth and time of water storage in rice tillering period should be 5 cm,lasting for 7 days.If considering the yield and loss of nitrogen and phosphorus,it is suggested that the depth of water storage should be 8 cm,lasting for 3days d.If only the amount of nitrogen and phosphorus loss caused by drainage after rainfall is considered,it is suggested that the storage depth be 8 cm and the duration be 7days.