Study On The Flowering Phenology And Pollen Characteristics Of The Clone Carya Illinoensis

Carya illinoensis is deciduous tree that is originated in Northern Mexico and Southern United States. As the fruits and trees are of high value, they are highly praised among the consumers and growers. In order to provide theory basis for varieties configuration and crossbreeding in plantation, this paper mainly analyzed the flowering phenology and pollen characteristics of6clone Carya illinoensis, including the flowering phenology, pollen morphology, pollen viability, pollen storage, and cross pollination. The results are as follow:The staminate and pistillate of different clone Carya illinoensis has different flowering phenology. The difference in flowering phase of the6clone pistillate flowers range from2to10days, and1to9days among the staminate flowers.Differences also exist among the same clone of different years, while the flowering sequences of different years are relatively stable. The flowering time of staminate and pistillate in different places is significantly different. In regard to the pistillate of No.104,the first flowering date of Jiande is27th April, the earliest among the three places. While Anji is the latest,3May. For the staminate of No.104, the initial dehiscence time of Jiande is10th may, Anji15th may, Yuhang12th may. The dehiscence duration lasts for8to10days, while the full dehiscence duration lasts for5to6days. Different canopy and direction of the same clone staminate and pistillate has different flowering phenology. For pistillate, there are slight differences among the4directions, as east and south are1day early than west and north. For staminate, the differences are not obvious among the4direction. However, the dehiscence time of high and low two layers of crown exist differences, and the high layer is1day early than the low layer.There are significant differences on the pistillate flowering number and staminate ordinal of the6clone Carya illinoensis(P<0.05).According to the observation of the6clone pollen with SEM, the6clone pollens are medium size, oblate shape (No.104is nearly round.). All pollens have three apertures which are evenly disposed on the equatorial plane. The equatorial plane of this6clone pollen are oval in shape, while the polar plane of clone No.5,21,27and104are nearly round, No.28and35nearly triangular. There are granular decorate on the surface of the pollen with granular risings equally distributed. Granular of clone No.21and27are distributed densely, and No.5and28are distributed sparsely, while No.35and104are distributed between the former two kinds. According to the cluster analysis of the6clone Carya illinoenis pollen, the9indices of each cluster are extremely close, such as clone No.35and104,21and27,5and28, which provides palynology explanation on the phylogenetic relationship.With one-way ANOVA analysis, it is found that pollen viability of the same clone under different treatment present significant differences (p<0.05).The sequences of pollen viability are as follow:desiccant treatment≈drought treatment>dry in constant temperature30℃>dry in sunshine. Pollen viability of the same clone in different dehiscence periods reaches significant differences (p<0.05). The pollen viability of Clone No.5,27,35is as follow:full dehiscence is higher than initial dehiscence, and final dehiscence is lower than initial dehiscence. Pollen viability of the same clone under24h,48h,72h drought treatment all reaches significant differences (p<0.05). Pollen viability of clone No.5,27,35presents that, collected after24h>48h>72h.The4kinds of storage have obvious effects on the pollen viability, such as storage in room temperature,0to5℃,-20℃, and-79℃. Under the room temperature situation, pollen viability of3clones (No.5,27,35) is low after16days storage. After30days storage, pollen of the3clones is out of viability. Under0-5℃, pollen viability of3clones is declined to20%after90days storage, while No.35is the most storage resistance, and the viability is still up to10%. Under-79℃and-20℃, pollen viability is much more storage resistance, as the viability of3clones after270days storage is22%to28%under-79℃, and13%to22%under-20℃.As for the cross pollination on the same female parent, there are differences with different male parents. Clone No.21and28have the highest compatibility with No.35among the3pollination clones, and clone No.104with No.5.As for the cross pollination on the same male parent, No.5,No.27and No.35have the highest compatibility all with No.21among the3female parent.