Study On The Growth And Physiological Characteristics Of Pinus Elliottii Male-Sterile Clone(SG001)

This is the first systematical study on the growth characteristics and male sterile mechanism of pinus elliottii male-sterile clone (SG001). The male-sterile clone was investigated by growth traits, morphological characteristics, cytology and physiobiochemic indexes. The focus of this study is to1) have the first understanding of the growth characteristics of SG001, 2) determine the period and mode in microspore abortive of the male sterile plants,3) investigate the physiology mechanism of abortion from the changes of some physiological and biochemical indexes in the male sterile plants of Pinus elliottii. The results of the study were as follows:(1) The tree height, diameter at breast height (DBH), crown breadth, individual volume (Vi), cone yield and chlorophyll contents of the Pinus elliottii male sterile clone SG001 were higher than those of the total clonal average between 9.01%～46.19%. Thereinto, the tree height and DBH were higher than the total clonal average of 15.61% and 9.01%. The height and DBH of the progeny of Pinus elliottii male sterile clone were higher than the total clonal progenies average of 2.84% and 0.99%. It showed that the clone of Pinus elliottii male sterility was exellenct in the growth and cone yield. But the growth traits of its progenies did not show obvious advantages. The correlation analysis among the growth parameters of the 18 Pinus elliottii clones showed that the male flowers quantity was extremely significantly negative correlated with DBH, crown breadth, Vi and cone yield.(2) The growth rate of male sterile microstrobilus of Pinus elliottii was slower than that of male fertile microstrobilus. The color of male sterile microstrobilus was purple while the male fertile microstrobilus showed to be yellow color, indicating that the male fertile microstrobilus begun to spread pollen and the male sterile microstrobilus were purple and dry. There were no pollen spreading out in the male sterile microstrobilus. It was the type of no pollen abortion typical.(3) Microscopic observation showed that the tapetum of Pinus elliottii male sterility microsporangium wall was not completely degradation in the period of mononuclear microspore. And, the nucleus of mononuclear microspore was degraded after completely released from tetrad. The cells remains of mononuclear microspore were wrapped by the microsporangium wall until the microsporophyll dry and fall off. The research suggested that the abortive of male sterile microspore occurred during the period of tetrad and mononuclear microspore. The tapetum delayed degradation might be one of the important reasons for Pinus elliottii male sterility.(4)The protective enzymes activities and MDA contents during male strobilus abortion were studied. Significant differences in the SOD activity of Pinus elliottii microstrobilus were found between male sterile line and male fertile line, but there was no obvious regularity among them.The POD activities and MDA contents of male sterile line were higher than these of male fertile line in the same period, and there were significant differences among them. However, the SOD and POD activities in the needles of male sterile line were lower than these of male fertile line in the same period. Moreover, no difference in MDA content could be found between male sterile line and male fertile line of Pinus elliottii needles. In the process of the microspore development, the SOD, POD activities and MDA contents in microstrobilus were significantly higher than those in needle of male sterile line at most of periods. While the SOD, POD of activities and MDA contents in the microstrobilus of male fertile line were lower than those in the needles in the same period. The research suggested that excessive POD activity and MDA content in microstrobilus might be one of the important physiological reasons for male sterility in Pinus elliottii.(5) The nutrients content in microstrobilus and needles of Pinus elliottii during male strobilus abortion was studied. The free amino acid contents in the needles of male sterile line were higher than that of male fertile line in all periods, and there were significant differences among them in most periods. Furthermore, the free amino acid contents in the microstrobilus of male sterile line were higher than that of male fertile line in the period of microspore mother cell, dyad, tetrad and after the mononuclear microspore nucleus degradation. No significant differences were found in soluble sugar contents of Pinus elliottii needles between male sterile line and male fertile line. But the soluble sugar contents in the microstrobilus of male sterile line were higher than that of male fertile line except for fertile microspore in tetrad and mononuclear microspore period. The proline contents in the needles were extremely low, and no significant difference was found between male sterile line and male fertile line. The proline contents in the microstrobilus of male sterile line were lower than that of male fertile line in the early stage of the microspore development. However, male sterile line was higher than the male fertile line in the later stage. But, no significant difference was found between male sterile line and male fertile line in the middle stage.