Effects Of Water,Nitrogen,and Plant Density Regulation On The Yield And Nutilization Effeciency Of Ratooning Rice Cultivar “Huanghuazhan”

To clear the variation of yield and N use effeciency in ratooning rice cultivar“Huanghuazhan”under the conditions of water saving&N decreasing,an field experiment was carried out with the cultivar“Huanghuazhan”as the material in Datonghu district,Yiyang city of Hunan province in 2016.Three factor of water saving,N fertilizer and density was studied by using split-plot experiment design.Water saving had three treatments(W1,conventional irrigation;W2,moderate water saving,irrigate with lower than 10cm under groundwater level;W3,deep water saving,irrigate with lower than 15cm under groundwater level).N fertilizer also had three treatments(N0,nitrogen-free;N1,local fertilization,357kgN/hm~2;N2,nitrogen decreasing,reduce 24%N quantity compared with the N1).Lastly,density had two treatments(D1,density decreasing,row&line spacing was20cm×20cm;D2,density increasing,row&line spacing was 20cm×16.7cm).Rice yield of the whole year,N use efficiency were determined.The main research results are shown as follows:1.Compared to the W1,the treatments of W2 and W3 did not affect the rice yield of first season and the ratoon season.The yield of the two seasons under in the W2,W3treatment were 5.43,2.75 t/hm~2 and 5.56,2.88 t/hm~2,respectively.The analysis of yield components was shown that effective panicles,spikelets per panicle,grain filling and1000-grain weight had no difference among the water saving treatments.2.Rice yield of the first season and ratoon season of the cultivar“Huanghuazhan”in the N1 and N2 treatment was significantly higher than that of N0 treatment,but there was no difference of rice yield of first season and the ratoon seson between the N1 and N2 treatment,the yield of the two seasons under in the N1,N2 treatment were 6.46 t/hm~2 and 6.47 t/hm~2,3.56 t/hm~2 and 3.26 t/hm~2,respectively.3.Rice yield of the first season and the ratoon season of the cultivar“Huanghuazhan”in the D2 treatment was 5.68t/hm~2,2.90t/hm~2,respectively,was significantly higher than that of the D1 treatment,that of the D1 treatment 5.34 t/hm~2 and 2.76 t/hm~2,respectively.The analysis of yield components was shown that effective panicles in the D2 treatments were significantly higher than that of the D1 treatment.4,Ratoon seasonal nitrogen uptake and the quantity of N uptake per 1000kg grain in the N1 and N2 treatment were 7.88 g/m~2,6.80 g/m~2?and 22.28 kg,20.81 kg,significant difference of the quantity of N uptake per 1000kg grain was observed between the N1 and N2 treatment.There was signicantly difference of agronomic N efficiency and N partial factor productivity between the N1 and N2 treatment,was 12.60 kg/kg,17.63 kg/kg and23.78kg/kg,36.25kg/kg,respectively.Consequently,the measurement of water-saving,nitrogen decreasing&density increasing could get first and ratoon seasonal high&stable rice yield in the cultivar“Huanghuazhan”,and increase agronomy utilization effeciency in the Dongting late plain area of the north of Hunan province,.