Influence Of Water And Nitrogen On Kinggrass Growth Characteristics And Preliminary Studies Of The Mechanism

The role of moisture and nutrients on the crop growth are not isolated, but are the mutual influence. Now the research of kinggrass focuses on influence of nitrogen on its yield or the quality, the research of water and nitrogen coupling are lack of this study, so we set up two test factor about the soil moisture and different nitrogen, to analysis the influence of water and nitrogen coupling of kinggrass on growth characteristics through the pot experiment, and to research preliminarily the physiological response. To research the influence of different water treatment on the kinggrass growth and response of water physiology.Finally, through the field experiment, the pot experiment results were verified. In order to provide a reference basis for water and fertilizer conservation of kinggrass, to promote the healthy development of grass industry in tropical areas.The main results were as follows:(1) The moisture was the key factor to restrict the kinggrass growth. Plant height reached the highest during75%-85%of soil field capacity.(2) In relative water content of soil were35%-45%,55%-65%,75%-85%conditions, the harvest time, the corresponding nitrogen rate of maximum yield were271.78,355.05,329.06kg·hm-2. Crude protein content was the highest when nitrogen rate were361.54,505.44,647.88kg·hm-2in harvest stage.(3) From the whole growth period, total absorptive amount of nitrogen, phosphorus and potassium can be seen, the most favorable for the absorption of them were the75%-85%of soil field capacity,55%-65%of soil field capacity was the second, and35%-45%of soil field capacity limited absorption of them.(4) In the jointing and harvest stage, with the deepening of water stress, proline accumulation increased, proline accumulation increased with nitrogen rate increase in the same moisture conditions. At the same time, proline accumulation was significantly higher than the jointing stage in harvest.CAT enzyme activity reduced with the deepening of water stress,35%-45%of soil field capacity was the lowest, CAT enzyme activity increased with nitrogen rate increase in the same moisture conditions.(5) In the same moisture conditions, with the increase of nitrogen rate, amount of use, amount of residue and loss amount, retention rate and loss late of nitrogen gradually increasing, but the utilization rate of nitrogen fertilizer revealed a trend of gradual decrease. (6) In this experiment conditions, the effect degree of soil moisture conditions on yield and quality of kinggrass higher than nitrogen rate, and they have obvious synergy, only if collocation of water and nitrogen are proper, will obtain higher yield and quality. The best water and nitrogen conditions were75%-85%of soil field capacity, amount of nitrogen were329.06kg·hm-2, this ratio can significantly improve yield and quality of kinggrass.(7) With the increase of soil water content, the relative water content of leaves overall were rising and was the maximum in65%-75%of field capacity. When field capacity above or below the treatment RWC would droped, when soil moisture content less than25%, RWC reduced greatestly, plant shew obvious water stress; Along with the rise of soil moisture content, free proline overall present trend of decrease. Kinggrass suffered more serious drought stress, the more time under duress, free proline accumulation become more in the body of the kinggrass. When the soil moisture content less than25%, free proline accumulation were maximum in kinggrass, significantly higher than other treatments.(8) The most suitable soil moisture content for kinggrass in our study was during65%-75%of field capacity, and the kinggrass could grow normally during55%-95%of field capacity, while the growth of kinggrass was limited during5%-45%of field capacity and95%-105%.(9) Control water treatment compare with general field water treatment, yield increased, and crude protein content also significantly increased, but the crude fiber content significantly reduced. In60%-80%of field capacity condition, kinggrass can obtain higher yield and quality.