中文摘要：

为掌握薄壳山核桃生长习性及落果规律,以‘Mahan’品种为研究对象,系统观测其开花结实物候期及其落果规律。结果表明,薄壳山核桃短果枝的芽一般为混合芽,芽体饱满,鳞片紧包,近圆形,萌发后长出结果枝和复叶,基部侧芽形成雄花序,并在近顶端形成雌花序。‘Mahan’花芽于3月中下旬开始萌动,3月底顶芽和雄花芽开绽,顶芽抽生结果枝,雄花芽抽生雄花序。4月初开始展叶,20 d以后基本达到叶面积最大值。结果枝、复叶、叶长和叶宽生长过程呈＂S＂曲线生长,与Logistic生长模型高度拟合。通过相关性分析显示结果枝、复叶、叶长和叶宽生长与有效积温呈显著正相关。‘Mahan’第1次落果现象出现在6月中旬到6月底,落果数占总果数的16.27%;第2次落果现象是在7月初至7月中旬,落果率达到68.75%;第3次落果现象是在8月份,落果率为2.2%。

英文摘要：

The flowering and fruiting habits of ＇Mahan＇ pecan were observed to study its biological charac- teristics and physiological fruit drop. The results showed that the pecan buds on the fruiting spur are usually mixed buds in near-round shape and tightly packed with scales. After germination, fruit bearing-branches elongated and ：ompound leaves appeared. The male inflorescence was developed from the lateral buds on the low portion of the branch and the female inflorescence was developed from the proximal top of the branch. From mid to late March, buds swelled and their outer scales shed. The inner scales split and the male inflorescence appeared and bloomed an an extended fruiting branch from the apical bud in late March. In early April, leaves expanded and reached the maximum size after 20-d growth. The growth patterns of the fruit-bearing branch, compound leaf, leaf length and leaf width all showed an ＂S＂ curve, which highly fit in the logistic growth model. A correlation analysis indicated significantly positively correlation between the growth and the effective accumulated temperature. The first time af the fruit dropping occurred at early to late June with a fruit dropping rate of 16.27%. The second time of the fruit dropping occurred from early to mid July with a fruit dropping rate of 68.75%. The third fruit dropping time was in August with a fruit dropping rate of 2.2%.