伏旱期土壤水分对再生稻的影响

高温伏旱期，再生稻头季稻齐穗后１５天排水，稻株冠层和２／３高处的日均温和相对湿度呈极显著相关，收后稻桩冠层的也然。在伏旱期，稻田土壤水分随排水期提早和土层深度降低而减少，土壤干旱，有机质，ｐＨ值和全Ｎ，Ｐ，Ｋ均较有水田低。齐穗后１５天排水的茎秆绿叶数少。粒重和结实率下降，产量较低，活芽短，但早熟，稻米的蛋白质含量增加，倒５节的活芽较其他处理和对照的长，再生稻的成苗率，成穗率，活芽利用率和穗茎比低。

AN INFLUENCE OF DIFFERENT SOIL MOISTURES ON RATOON RICE IN HOT SUMMER DAYS

During the hot summer days,different drainage experiments with the main crop of ra-tooin rice show that tlie mean day temperatur and the relativ moisture in the top and thetwo third of a plant are respectively higher and lower by drainage than by non drainage atthe 15th day after full heading,Furthermore,there is a significant negative relationshipbetween the mean day temperature and the relative moisture. Meanwhile, there are lowercontents of organic substance,pH,N,P and K in the dry field than in the paddy field,Soil moisttire decreaes with early drainage and thin layer. Drainage at the 15th day afterfull heading results in the ripeiiess of rece,the decrease of leaf number and grain weight,the drop of fertility and yield, the increase of protein conteiit and the shortening of budsbut the lenghtening of buds on the fifth node down from the top of the main crop. Aterwards, it causes the decrease of seedling percentage, panicle percentage, bud survival per-centage and panicle-to-stem ratio, the delay of heading period and the shorthening of a ra-tooning plant, which hence ruin the economic characteristics of ratoon rice; The yield is 80kg grain per mu in such a situation. The mean soil moisture contet of different drainageexperiments is 34.3%.The discussion on the influences of different drainage experimentson ratoon rice in the dog days show that some proper cultivating techniques are needed toreduce the infltience of dratight and increase the percentage of ratoon rice harvest.