不同时期遮光对玉米籽粒生产能力的影响及籽粒败育过程的观察

通过对玉米植株进行分期遮光试验，认为；雌穗小花分化期至籽粒快速灌浆始期是影响玉米穗粒数的关键时期；雌穗小花分化期至籽粒快速灌浆高峰期是玉米植株产量形成的关键时期；吐丝期是决定单株产量和穗粒数的临界期；对百粒重有显著影响的时期是胚乳游离核期和快速灌浆期；果穗顶部籽粒比中、下部籽粒发育较迟，当中、下部籽粒进入快速灌浆期时，顶部籽粒则停止干物质积累，成为败育粒。

EFFECTS OF SHADING TREATMENT AT DIFFERENT STAGES OF PLANT DEVELOPMENT ON GRAIN PRODUCTION OF CORN(ZEH MAYS L.)AND OBSERVATIONS OF TIP KERNAL ABORTION

Studies were carried out in 1984, 1985 to determine the effects upon grain production of artificial shading treatment with 6-9 successive 5-day periods at different stages of plant development in the field to two cultured hybrids of corn (Zea mays L.)Beijing early No. 7 and Yellow 417. Results indicate that grain yield is affected significantly by shading treatment during the period of 12 days before silk advancing to 22 days after silking; grain number of ear is effected significantly from the stages of differnation of pistillate inflorescence to the onset of LDMP (the period linear dry matter accumulation in the kernals). The periods of remarkably influenced by shading treatment on 1O0-grain weight include both free-nuclear stage of endosperm and LDMP. The critical period for both grain number of ear and grain yield of plant are at silking stage. The development of kernals at the tip of the ear lags several days behind that at the base and the median of the stalk during the period from the beginning of silking to the onset of LDMP. Tip kernals cease dry matter accumulation at the onset of LDMP and become abortion. The shading period of showing significant effect on the number of abortive kernals ranges from 3 to 17 days (onset of LDMP) of postsilking.