Mechanism of deleyed development on young panicle in sorghum varieties

1. 通过温室试验，阐明了温度和光周期的相互作用。结果表明，在22-24℃的低温条件下，光敏品种玉金稻的穗萌发期（出苗至幼穗萌发期）最短持续时间为16小时。穗萌发期随日温度变化条件的变化而变化（24 [[SY.+]]）。() 0-24 (SY。+ -。[)6⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯在田间条件下，对部分品种进行穗萌发前12小时、3天、6天和9天的短日照处理，结果表明品种的基本营养期（BVP）持续时间在3 ~ 9天之间，高温会使BVP持续时间缩短。光敏相的持续时间为3 ~ 6天，温度高于22 ~ 24℃时，光敏相的持续时间增加。本研究证实，为了建立准确的高粱品种抽穗时间估算模型，需要将整个萌发前期划分为两个阶段。某些光敏品种的高温延迟加热现象有待进一步研究。

1. Greenhouse experiment were conducted to clarify the interactions of temperature and photoperiod. From the results for Ryuujinwase (photosensitive variety), the minimum duration of panicle initiation (emergence to young panicle initiation stage) was observed by 22-24ﾟC in long daylength (16hrs) condition.2. The period of panicle initiation was varied with diurnal temperatur change conditions (24(]SY.+-。[)0-24(]SY.+-。[)6ﾟC), and there was high correlation coefficient between the duration of panicle initiation and effective accumulate temperature (critical temperature ; 22ﾟC).3. From the results of short daylength treatments (12hrs ; 3,6 and 9 days) before panicle initiation time in field conditions using some varieties, the durations of BVP (basic vegitative phase) of varieties were estimated ranging from 3 to 9 days, and the durations of BVP were reduced by hifh temperature. And also, the durations of PSP (Photo sensitive phase) were estimeted ranging 3-6 days, and the durations of PSP were increased at temperature above 22-24ﾟC.4. This study confirmes the necessity to divide the entire pre-initiation period into the two phases for accurate estimation model for heading time in sorghum varieties. Futher studies are needed to elucidate the phenomon in some photo-sensitive cultivars of the deleyed heating by high temperatures.