| With the increase of planting density,the condition of ventilation and penetrating light became worse. Therefore, in high plant density conditions, it becomes a key that how to improve the corn canopy structure, increased air and light conditions in maize cultivation. During 2008-2009 growing season, the experiments were carried out in the Dong Tang village Dong Ping county and state key laboratory of crop biology that the field experiment was conducted. Used Denghai 701(a super-high yielding maize variety) as the experimental material, and planting densities was 90000 plants/hm~2, and four row spacing forms (60+60,70+50,80+40,90+30). In the super-high yielding condition, effects of row spacing forms on the maize yield and canopy apparently photosynthesis characteristics were explored. The main results as followed:1.Effects of row spacing forms on plant characters, yield, as well as its components of maizeUnder the density in our experiment, the height of plant and ear of the"80+40"was the lowest in the 4 row spacing forms, while compared with the others, the yield, kernels per row, kernels per ear and 1 thousand kernels weight of the"80+40"were were remarkably higher than"60+60"and"70+50", but all results above was the lowest in the row spacing form"90+30". In the 4 row spacing forms, there was no different in lines per ear.2. Effects of row spacing forms on the dynamics of dry matter accumulation of maizeIn our study, compared with other 3 forms, the dry matter accumulation of maize population in"80+40"form was the highest, especially at later development stage. However, the dry matter accumulation per single plant of ear leaf layer, under ear leaf layer, single plant leaves and single plant stem of"80+40"form were higher than other 3 forms, while which of upper ear leaf in"80+40"was lower than others.3.Effects of row spacing forms on the ear leaf photosynthetic characters of maizeIn our study, the ear leaf chlorophyll content, Pn, Fv/Fm,ΦPSⅡand the activities of PEPCase and RUBPCase of"80+40"form were obviously higher than other 3 forms, particularly at later development stages. Results showed the ability of ear photosynthesis can be prolonged and enhanced in the form of"80+40", the photosynthetic capacity of ear leaves was raised by the optimum row spacing form.4.Effects of row spacing forms on ecological factors of maize populationThe different layer canopy photosynthetic active radiation (PAR) capture ratio of all 4 forms changed from strong to weak when leaf layer turned lower, while the total capture ratio of form"80+40"was the highest of all. Furthermore, the upper capture ratio of"60+60"was the highest, and which declined as the broad row spacing side widened. The PAR on ear leaf layer and under ear leaf layer of"80+40"was the highest of all. As result, the form of"80+40"was propitious to increase PAR of under layer, which retard mid-under leaves layer senescence and prolong stay green time. The air temperature in maize population can be increased in form"80+40", at the anthesis stage, the inner population air temperature of form"80+40"was 0.7, 0.5 and 1.1℃higher than form"60+60","70+50"and"90+30". It enhanced the enzyme activities ranged photosynthesis and improved the Pn of form"80+40"as well. The other side, the form"80+40"could reduced the relative humidity of ear leaf layer, which was propitious to increase the anti-adversity of plant.5.Effects of row spacing forms on apparently photosynthesis characteristics of maize populationIn the 4 different row spacing forms, the leaf area index (LAI) was highest at grain filling stage, and then turned lower after that, which sharply declined at dough stage. Of the 4 forms, the LAI of form"80+40"was the highest, which decreasing amplitude after anthesis was the lowest as well. It showed the form"80+40"was propitious to stay the relative high LAI and enhance the area of green leaf. The canopy apparently photosynthesis rate (CAP) after anthesis increased corresponding to the senescence, which was highest at grain filling stage. The CAP among different row spacing forms was"80+40">"70+50">"60+60">"90+30". The canopy respiration (CR) decreased first and increased later after anthesis, which was the lowest in the form"80+40". The CR/TCAP changed as the same as CR, which was the lowest in form"80+40"as well. In the form"80+40", the population photosynthetic rate was increased and CR/TCAP was declined.6. Effect of row spacing forms on leaf senescenceIn the plant, superoxide, hyperoxide and peroxide damage the normal functions of cell, while which can be cleared up by antioxidase such as SOD, POD and CAT. In the process of senescence after anthesis, the enzyme activity of SOD, POD and CAT declined gradually, but which was higher than others in form "80+40", this advantage was obvious at the later grain filling stage, especially. In our study, the antioxidase activity could be stayed in form"80+40", which prolonged the normal functions of maize leaves.As results showed, in order to obtain high yield, we should choose an appropriate row spacing form can bring individual developmental potential to full play, coordinating the population and individual development and guaranteeing higher yield. Considering obtaining the higher and stable yields, the optimal row spacing form for Denghai 701 was"80+40"in the conditions of this experiment.
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