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在玉米杂交制种中,花期相遇是保证制种田高产的关键。除人为因素外,双亲在生长发育过程中受特殊的气候条件影响,或者外引的亲本因地理环境条件的改变,都可能导致花期不遇。因此,做好花期预测,搞好花期调节对提高杂交制种田产量至关重要。 1 花期的预测为使双亲花期相遇,一般应使父本生长比母本稍晚些。花期预测通常采用未出叶片计算法和雄穗大小比较法。未出叶片计算法:是通过对双亲未出叶片数多少进行比较来预测花期。一般父本未出叶片数要比母本未出叶片数多1.5～2片,也就是父本比母本晚5～6d。而母本从抽雄到吐丝的过程大约需要5～6d的时间,这样恰好父、母本花期相遇。雄穗大小比较法:是通过对双亲抽雄前的雄穗大小进行比较来预测花期。通常将抽雄前的雄穗分为3个时期,即雄穗的前期、中期和后期。在前期时母本的雄穗1～2cm长,而父本的雄穗应在0～0.5cm长;在中期时母本的雄穗3～6cm长,而父本的雄穗应在1～3cm长;在后期时母本的雄穗7～15cm长,而父本的雄穗应在4～7cm长。这是通过对雄穗大小的比较来预测花期相遇的一般规律。
In the hybridization of maize, flowering is the key to ensure high yield of farming system. In addition to human factors, the parents in the process of growth and development by the special climatic conditions, or lead the parents due to changes in geographical conditions, may result in flowering not happen. Therefore, to do a good job of flowering forecast, do a good job of flowering regulation to improve the yield of hybrid seed production is essential. 1 Flowering Prediction In order to meet the parents of flowering, generally should make the growth of paternal than the mother later. Flowering prediction is usually based on the leafless method and tassel size comparison method. Not out of the leaf calculation method: Through the number of leaves on the parent did not compare the number to predict flowering. The average number of undeveloped leaves is 1.5 to 2 more than that of the female parent, that is, 5 to 6 days later than the female parent. The mother from tasseling to silking process takes about 5 ~ 6d of time, so just father, female flower encounter. Ear size comparison method: It is estimated by comparing the size of the tassel of the parents before mating. The tasseled tassels are usually divided into three periods, namely the pre-tassel, mid-tassel and post-tassel. In the early stage, the female tassels are 1 ~ 2cm long, while the male tassels should be 0 ~ 0.5cm long. In the middle, the male tassels are 3 ~ 6cm long, while the male tassels should be 1 ~ 3cm long; in the late maternal tassel 7 ~ 15cm long, while the male tassel should be 4 ~ 7cm long. This is a general rule that predicts the encounter of flowering by comparing tassel size.