Abstract:

Two four-year-old Beta grafted grape cultivars‘Jingmi’（Vitis vinifera‘Jingmi’，a low light tolerant cultivar）and‘Summer Black’（V. inifera–V. labrusca‘Summer Black’，a low light intolerant cultivar）were sampled to study the grape flower buds differentiation of cultivars with different tolerance 

to low light，which can be used as theoretical foundation to solve the problem of‘alternate bearing’under protected cultivation to promote early maturing. The bud differentiation process at the 2nd to 7th nodes was observed by the paraffin section technique and the relating developmental process figure of sample dates and differentiation ratios was also made. The results indicate that：（1）The formation of inflorescence main axis can be used as the mark for the beginning of the flower buds differentiation.（2）The period from the young shoots having two leaf primordium to the formation of anlagen，which can also be called the stage of physiological differentiation，was key to inducing the flower buds differentiation，and the period of anlagen differentiation and after it breaking up to two branches was the key stage to regulate flower buds differentiation for the grape under greenhouse.（3）The synchronous development of the growing point at young shoots and the anlagen of buds was essential for flower buds differentiation. High activeness of vegetative growth of the growing point at young shoots can inhibit the flower bud differentiation，which might lead the problem of‘alternate bearing’.（4）The weak light resistant cultivar‘Jingmi’has high adaptability to protected cultivation to promote early maturing. Each stage of differentiation of their buds at each node was short and barely overlapped. The flower buds differentiation of‘Jingmi’，without evident difference of buds differentiation ability，was beginning at the basal nodes of shoot，and the differentiation of high nodes was late，but fast. The usual pruning measurements leaving the 2nd or 3rd bud could get sustainable production for protected cultivation to promote early maturing. By contrast，the weak light unresistant cultivar‘Summer Black’cannot completely adapt to the environment of early maturation cultivation. Each stage of the differentiation of the buds at each node was long and some of them overlapped irregularly. Although the number of flower buds increased and their quality improved gradually，the number and quality of flower buds from the 2nd to 7th nodes couldn’t meet the commercial production demands and the problem of‘alternate bearing’was still serious. Necessary measurements like renewal pruning are needed to keep the sustainable production of protected cultivation to promote early maturing for this cultivar.

Key words: grape, protected cultivation to promote early maturing, tolerance to low light, flower bud differentiation