Studies On Effect Of Nitrogen Rate And Sowing Date On Photosynthesis And Yield In Different Maturity Maize

Maize is an important food and forage crop in China, the corn varieties moved eastward in the northeast and corn varieties become more and more under the condition of climate warming. In this paper, by measuring different ripe period of maize varieties and different sowing date at different growth period of photosynthesis and yield under different nitrogen levels of photosynthetic indexes and production indexes and plant, soil nitrogen levels, to explore the best period of corn varieties 、sowing date range and the best application rate for maize photosynthetic, The main researches as follows:(1) Choose 8 corn varieties which was common in northeast,(early-maturing :Jidan 27、Suihe369; mid-maturing: Xianyu 335、Dika516、Limin 33;mid-lata-maturing :Nonghua 101、Zhengdan 958、Jingke 968). During the reproductive period, respectively the three phases of ripe corn varieties photosynthetic rate 、transpiration rate、stomatal conductance、chlorophyll content and the yield in 2013-2014, The results show that, early-maturing and mid-maturing with strong Pn ability and better yield with small difference, the mid-late-maturing has the different conditions without has the higher yield.(2) Choose 3 corn varieties(Xianyu 335、Zhengdan 958、Tunyu 88)which has 5 sowing date(on April 30, May 8, May 13, May 18, May 23), determinate of each processing of photosynthetic rate, transpiration rate and chlorophyll content on June 30, July 27 and August 20 and yield at the end of September. The results show that,the maize can not ues the energy resources better and has lower yield which was planted at the end of May, but there were no big differences in photosynthetic characteristics and yield at the sowing date between the end of April and mid-May.(3) Determination the photosynthesis, plant nitrogen content, soil inorganic nitrogen content and production of Xianyu 335、Zhnengdan 958、Suihe 369、Liangyu 99, with the N fertilizer lever respectively 0、120、180、240kg/hm2 and the same P K fertilizer, With the increase of n application rate, aboveground biomass increased by 45.9%、24.4%、25.8%、25.8%, plant total nitrogen content increased by 40.9%、38.6% 、49.4%、73.3% and the yield increased by 74.2%、34.6%、59.9%、67.9%, respectively. Increasing nitrogen application can effectively improve the plant nitrogen content, soil nitrogen content and production. Increasing nitrogen application significantly increased the photosynthetic capacity of each corn. when nitrogen application of 180 kg/hm2, Xianyu 335’photosynthetic rate and chlorophyll content is higher, with further increasing nitrogen application, the photosynthetic capacity and chlorophyll content declined, Zhnengdan 958、Suihe 369、Liangyu 99 have the best photosynthetic rate and yield under the N fertilizer is 240kg/hm2.(4) Correlation analysis of corn photosynthetic indicators in different periods, production index, nitrogen content,the conclusion is between different corn varieties, photosynthetic rate, transpiration rate and good relationship and the roduction and chlorophyll content, has a significant positive correlation between soil inorganic nitrogen content.