Effects Of Different Nitrogen Application And Density On Population Growth And Yield Of Early Rice By Mechanical Hill Direct Seeding

The field experiment of this study was carried out in Guangfu village experimental base of Nanchang country, Nanchang, Jiangxi province in 2013-2014, and the laboratory study started in the key laboratory of crop genetic breeding and physiological ecology of Jiangxi Agricultural University. Zhongjiazao 17, Zhuliangyou 819 and Zhongzao 35 were chosen as test materials.in both years. Nitrogen application test with five treatments was conducted in 2013, the proportion of base, seedling, tillering and panicle fertilizer = 4:0:3:3, 4:1:2:3, 4:2:1:3, 4:3:0:3, 4:4:0:2,respectively.Four row spacing(11 cm and 14 cm, 17 cm, 21 cm) and two sowing rate(3 grains per hole and 5 grains per hole)were conducted in 2014. All varieties were sown in early April and we also inspected population growth and yield. And then defined the reasonable nitrogen fertilizer and seeding rate of early rice by mechanical hill-drop drilling in Jiangxi based on the above indicators. The results showed that:1 Effects of different nitrogen application on population growth and yield of early rice by mechanical hill direct seeding(1) Under different nitrogen fertilizer management, nitrogen postponing and reducing seedling fertilizer at the same time increased the yield of Zhongjiazao 17 and Zhuliangyou 819. Under the treatment of N2(basal: seedling: tillering, panicle fertilizer = 4:1:2:3) Zhongjiazao 17 and Zhuliangyou 819 obtained the highest yield. The yield of Zhongjiazao 17 was significantly positively correlated to productive panicle number and the yield of Zhuliangyou 819 was significantly positively correlated to the setting rate.(2) Under different nitrogen fertilizer management, with the increasing of fertilizer in later period, increasing seedling fertilizer, the dry matter accumulation of Zhongjiazao 17 and Zhuliangyou 819 increased. Under the treatment of N2 from booting stage to mature stage, Zhongjiazao 17 and Zhuliangyou 819 had the largest dry matter accumulation, and it was significantly positively correlated to yield. Similarly, under the treatment of N2, the dry matter accumulation of panicle, differentiated floret number and nitrogen uptake achieved the maximum and productive tiller percentage was the highest, all significantly positively associated with yield.(3)Under different nitrogen fertilizer management, the ear length of Zhongjiazao 17 and Zhuliangyou 819 were highest under N2,which was significantly positively correlated to yield, correlation coefficient was 0.9265 *,but was significantly negatively correlated to the lodging index. Under the treatment of N5(basal: seedling fertilizer: tillering, earring fertilizer = 4:4:0:2), the single stem breaking-resistance was the largest and negatively correlated to lodging index, but positively correlated to culm phenotype index, the correlation coefficient was 0.8913 *,0.8812 respectively.2 Effects of density on population growth and yield of early rice by mechanical hill direct seeding(1)Under the different density, the yield of Zhuliangyou 819 reduced with the increasing of row-spacing and sowing rate of each hole; the yield of Zhongzao 35 reduced with the increasing of row-spacing, but increased with sowing rate of each hole. Zhuliangyou 819 had the highest yield under the density of L1B1(11 cm row spacing, 3 grains per hole), and Zhongzao 35 had the highest yield under the density of L1B2(11 cm row-spacing, 5 grains per hole). The yield of two varieties had a significantly positive correlation with productive panicle number, and a significantly negative correlation with the grains per spike. As the hybrid rice Zhuliangyou 819 has a strong tillering capacity, should reduce the sowing rate of each hole properly. The conventional rice Zhongzao 35 has a weak tillering capacity, increase the sowing rate of each hole properly can increase productive panicles per unit area, so as to increase production.(2)Under different density, dry matter accumulation of Zhuliangyou 819 reduced with the increasing of row spacing and seeding rate of each hole; that of Zhongzao 35 reduced with the increasing of row spacing, but increased with the increasing of seeding rate of each hole. The Zhuliangyou 819 and Zhongzao35, nitrogen accumulation of panicle increased with the increasing of row spacing. The production of two varieties obtained the largest nitrogen accumulation under the 21 cm row spacing. The light transmittance of Zhuliangyou 819 and Zhongzao35 increased with the increasing of row spacing, and reduced with the seeding rate of each hole. Zhuliangyou 819 had the highest dry matter accumulation under the density of L1B1, Zhongzao 35 had the highest dry matter accumulation and productive tiller percentage which were significantly positively correlated to yield under the seeding rate of L1B2.(3)Under different density, the single stem breaking-resistance of Zhuliangyou 819 had a significantly positive correlation with bending moment, reduced with the increasing of row spacing and sowing rate; the single stem breaking-resistance of Zhongzao 35 had a significantly positive correlation with broken force. Under the same row spacing, the large sowing rate, the easier Zhuliangyou 819 lodging, but Zhongzao 35 was on the contrary.