文冠果人工种群的果实发育与落花落果特性研究

以甘肃定西生长的文冠果为对象，探讨了文冠果果实发育特征及落花落果规律。结果表明：（1）文冠果果实生长发育历经约2.5个月，生长发育主要在花期后的40 d内。果实发育特点为：在花期过后的10 d内生长最快，增长率达193%，此后一月仍保持较快的生长速度，月增长率达120%，而最后一月生长比较缓慢，月增长率仅为7%，整个发育期内横径发育速度一直大于纵径；（2）文冠果落花落果主要发生在果实生长发育的初期，且落花落果率高，达94.65%(落花率5.74%，落果率88.91%），坐果率低，只有5.35%。其落果特点为：落果是一个持续的过程，自花期过后果实膨大到成熟一直在落果，但也存在一个落果的高峰期，即花期过后的10 d内，落果最严重，落果率约达40%。研究认为，从保花保果的角度考虑，开花末期是文冠果水肥管理的重点时期。但从文冠果开花过于繁茂和可孕花分布过于集中而大量消耗树体和顶花序养分，从而造成严重的落花落果的现实考虑，应在开花末期和幼果期疏花疏果或任其自然落花落果，但均应加强果实发育中后期的水肥管理，从而提高坐果率。

Characteristics of Fruit Development and Flower and Fruit Drops of Artificial Population of Xanthoceras sorbifolia

The characteristics of fruit development and flower and fruit drops of Xanthoceras sorbifolia in Dingxi district of Gansu were studied.The results showed that:(1) X.sorbifolia fruit need about 2.5 months from developing to ripening,and its main development and growth stage was in the 40 days after flowering.Its fruit development feature was as follows:fruit growth was the fastest in 10 days after blossom period and its growth increment rate reached 193%,in the next month the fruit still keep faster growth and had a growth increment rate of 120%,but it grew slowly in the last month and the increment rate was only 7%,and during the whole growth process,the width of fruit grew always faster than the length of fruit;(2)X.sorbifolia flower and fruit drops occurred in the early stage of its fruit developing and growing process,and it had a higher drop rate of flower and fruit of 94.65%(flower drop rate 5.74%,fruit drop rate 88.91%),but a very low fruit-bearing rate of 5.35%.Its feature of flower and fruit drops was as follows:the fruit drop was an ongoing process and there was always fruit drop from fruit expanding to ripening after blossom stage.However,there were some peak days in fruit dropping,namely in the 10 days after blossom stage the fruit drop was very serious and the fruit drop rate nearly reached 40%.According to this study,it was regarded that,for the consideration of preserving flowers and fruits,the late flowering stage was the key period for X.sorbifolia to enhance the water and fertilizer management.However,considering the facts that X.sorbifolia profuse flowers and the concentration of fertile flower could lead to heavy drops of flower and fruit because of its high consumption nutrients of tree and top inflorescence,it should thin flower and fruit or let it drop naturally in late flowering stage and young fruit stage,but strengthening water and fertilizer management is needed in the middle and late periods of fruit development to promote its fruit-bearing rate.