| Cedar [Cedrus deodara(Roxb.)G.Don], Pinaceae, Cedrus Trew. Pinaceae is a total of 10, mostly single-cone, and monoecious. There are four kinds of cedar that is the case of Cedar deodara, C.libani Rich, C.brevifolia (Hookf.) Henry and C.atlantica Manetti.They are spreading out in the Himalayan stopped, western Asia, Cyprus and North Africa and other places. Among them, the Cedrus deodara, dioecism, is a good material to study the mechanism of sex differentiation of Pinaceae.Cedar is important species for Landscaping, duing to inconsistent flowering and pollen period dustering air pollution, causing allergies, and so studying the Biological characteristics of pollen in Cedrus deodara is an important practical significance.In this paper, cedar of different gender karyotype, the sex ratio of cedar and the biological characteristics of pollen to do a systematic study. The first aim is to investigate the level of cedar in the cytology of sex-determining mechanism of sex determination and early, and the second study of cedar pollen viability status of the situation, researching the appropriate cedar pollen germination medium, temperature and different storage conditions and storage period on the impact of pollen viability, and in order to do a good job of artificial pollination work, provided a good technical support for the Cedar genetic breeding.⑴Cedar trees of different sex, respectively, for the karyotype analysis, to explore the level from the cytology of sex-determining mechanism of cedar.①Karyotype analysis of cedar, selected tip position, based on methods of convenient and fast.②Tip of the Cedar pre-treatment selected the second p-saturated. In order to obtain better chromosome and set three different time periods of pre-treatment, results showed that the pre-treatment for more than eight hours is better.③Cedar female, male, monoecious chromosomes are 24, that is, 2n = 24, no aneuploidy and polyploidy variation of the phenomenon had not been seen in B chromosome.④Cedar trees are of different gender made of the Metacentric (m), Submetacentric chromosome(sm), there is no Acrocentric chromosome (st) existing. Karyotype formula are K (2n) = 24 = 18m +6 sm, which has pairs of chromosomes 10, 11, 12 Submetacentric chromosome, with the rest being the Metacentric.⑤Cedar female, male, monoecious 1, 2, 9 in the first of the short arm of chromosome there with the body, but the male's first and only nine pairs of chromosomes with a chromosome with the body. Studies have shown the first nine pairs of chromosomes may be related to sex differentiation.⑥Cedar trees of different gender are no less than the average arm or the length of chromosomes, but there are differences. The average arm of male is larger than female, female than monoecious. The length of the chromosome, the male than female, female than monoecious.The basis of the average arm ratio responses its original, the length of chromosome responses its nuclear-type of symmetry drawn between the cedar trees of different sexes of the evolution to the evolution from the original: monoecious→female→male.⑵Determining the pollen viability of cedar male, monoecious.①From the pollen viability can not see the gender differences that can not solve the cedar pollen study of the sex-determining mechanism.②Scattering peak in the powder collected pollen germination rate is not higher than the open, just open, and sprinkle powder phase.Time to concentrate on collecting pollen 9:00-14:00 in the morning, the afternoon can also be collected. Acquisition is a good selection of sealed paper bag.③The best pollen germination temperature is 20℃; The most appropriate medium for the mediumⅡ-10% sucrose +2% agar +0.01% boric acid.④Cedar pollen of the best storage conditions for refrigerated and dry.Different storage conditions and storage period of pollen viability and significant relationship.With the extension of storage period of pollen viability majors downward trend.In different storage conditions and storage period, changes in viability vary, 4℃refrigerator for pollen viability is slowest rate of decline, indoor storage under dark conditions, the fastest decline in pollen viability, almost zero about one month at room temperature to preserve the natural conditions of the second decline in pollen viability. Refrigerated storage conditions, after 3 months to maintain a high germination rate, one year later there is still a living force. Comprehensive study of pollen viability, pollen germination rate of the impact of the important factors are: temperature, medium type, and pollen storage conditions and storage period.⑶Cedar cone has a certain law of distribution. Studies have shown that Ceder ball of male has of differences in horizontal distribution and the existence of of the southern cone up to the crown. Also in the vertical distribution are differences, mainly in the lower part of the crown, of which the largest amount are in central distribution. Female flowers are mainly distributing in the ball in the upper canopy, flowers small, there are some difficulties to investigate.Pollination mechanisms of Cedar is the wind as the main media.⑷The proportion of Cedar mature sex survey in Taian city found:①Taian mature Cedar City are distributing on the most of the old campus, hospitals, government compound, the construction of the street earlier.②Taian, the proportion of female and male nearly 1:1, a higher proportion of monoecious, nearly 20%.③Gender lines in the course of the investigation and found that the top growth coniferous microspore phenomenon.
|
PDF Full Text Request