Study Of Water Regulation On The Inferior-grain Plumpness Of Rice

To clarify the water transfer in rice plant and its effect on grain plumpness,the water experiment was performed under waterproof canopy at the farm of henan agricultural university with yujing6 and liangyoupeijiu as materials from 2005 to 2006.Keep shallow water after heading(w1)and keep 65%of maximal water content of field after heading(w2)two water treatments were setted to study the dynamic changes of water content,dry matter content,bleeding intensity and sap flow in different position of rice plant and theirs influence on grain plumpness as well as the transpiration of glume and the factors that could affect it under different water treatment during grain filling stage.The results were showed as follows:1.The seed-setting,panicle grain and 1000-grain weight of two varieties were decrease remarkably under water stress and the yield of yujng6 and liangyoupeijiu respectively decrease 30.7%and 26%that compared with keep shallow water treatment.The effect of water stress on appearance quality was smaller than that on milled quality of rice.Appearance quality of yujing6 was inferior and liangyoupeijiu was improved under water stress.Eating qulity of rice was inferior under water stress.2.Grain filling rate was decrease distinctly under water stress.Yujin6 exhibited single peak curve and liangyoupeijiu was double peak curve.The effect of different water treatment on grain filling stage was different.To yujing6,the difference between superior and inferior grain was increased during middle grain filling stage and was increased during early grain filling stage to liangyoupeijiu.Compared to superior grain,inferior grain plumpness of two varieties changed worse because of decreasing grain filling rate.3.The change of water content in different leaf stem and sheath position was well-regulated during grain filling stage.Water content among different leaves were 4th＞3rd＞2nd＞1st;among different stems were 2nd＞1st＞3rd＞4th before 15 days after heading; among different sheaths were as same as leaves.Water content of grain decreased ceaselessly during grain filling stage and superior grain decreased faster than inferior grain,but water content of inferior grain was higher than superior grain.The relationship between water content in different leaf stem and sheath position and inferior grain plumpness was most consanguineous at 5^th,15^th,20^thand 25^thdays after heading and was significantly negative correlation,the water content of different position was increased under water stress.To yujing6,the relationship between water content in grain and superior and inferior grain plumpness was significant or rather significant negative correlation at 5^thday after heading and was significant or rather significant positive correlation at 30^thday after heading;to liangyoupeijiu,the relationship between water content in grain and inferior grain plumpness was significant negative correlation at 5^th and 35^thday after heading and was significant positive correlation at 25^thday after heading.4.The soluble sugar and starch content in above leaf stem and sheath were higher than below and the contribution of export to grian presented stem＞sheath＞leaf.The soluble sugar content in leaf stem and sheath accumulated at 5-10 days after heading and exported quickly in 10～20 days or 15～25 days and accumulated again after 25^thday;the starch content in leaf stem and sheath had no remarkable accumulation process and exported at 5^thday after heading.Water stress promoted export of soluble sugar of yujing6 in sheath and promoted export of soluble sugar of liangyoupeijiu in leaf and stem, but decrease the content of soluble sugar and starch in leaf stem and sheath.To yujing6,the relationship between soluble sugar content in leaves and inferior grain plumpness was significant or rather significant negative correlation at 30^thand 35^thdays; the soluble sugar content in stem and sheath was significant positive correlation with superior grain plumpness at 15^thday after heading and was significant or rather significant positive correlation with inferior grain plumpness at 5～25 days.The starch content in leaf stem and sheath was significant or rather significant positive correlation with superior and inferior grain plumpness at 5^thday after heading;the starch content in sheath was significant positive correlation with superior grain plumpness at 10^thday after heading and was rather significant positive correlation with inferior grain plumpness;the starch content in leaf was significant or rather significant negative correlation with grain plumpness at 15^thand 20^thdays and was rather significant positive correlation at 35^thday.5.The change of bleeding intensity of yujng6 in basal internode was single peak curve and reached max at 10^th,w1 was higher than w2;the trend of neck internode bleeding intensity of w1 was flexuous descend and appeared max at 10^th,20^thand 30^thdays,w2 descended straight.The change of bleeding intensity of liangyoupeijiu in basal internode was double peaks curve and appeared max at 15^thand 30^thdays.The daily change of basal internode bleeding intensity presented w1 higher than w2 at 8:00～2:00 and w2 higher than w1 after 2:00;w1 descend gradually from day to night well w2 increase gradually. the neck internode bleeding intensity of two treatments were small at 8:00～20:00,w1 increased rapidly after 20:00 and reached max at 23:00～2:00 and then descend quickly; w2 was low all the time.6.The sap flow in basal and neck internode changed along with temperature and high in day and low in night.The sap flow in basal and neck internode decreased under water stress and there were still a little in night,but there were little under w1 and almost zero. The relationship between neck internode and grain plumpness was consanguineous.7.The regulation of daily change of glume transpiration was high in day and low in night,affected by temperature.The glume transpiration reached max at 12:00～15:00 during early and middle grain filling stages but reached max at 9:00～12:00 during later grain filling stage.Along with grain filling,the differences of max glume transpiration rate between w1 and w2 minished first and then broaden,w1 was higher than w2.