Study On The Vivipary Characteristics Of Summer Squash Seed

Seed is the base of the production of summer squash and the breeding of new varieties,abut also the key of studying on seed with summer squash varieties.In order to explore the vivipary characteristics of summer squash seed,summer squash inbred lines A2,B-2,F,J,Q2,Q3,S-16-4,3,9 and Chinese pumpkin L0 were used as test materials in this study.And their seed fruits were Respectively picked in 35 days,45 days,50 days after pollination,then respectively for 10 days,20 days,30 days after-ripening treatment.And the experiment showed that the vivipary phenomenon of seed,the changes of vivipary rate,the anatomical structure of seed coat and the dynamic changes of endogenous ABA,GA content of different parts in seed fruits were analyzed.The main results are as follows:1.In this experiment,the vivipary of summer squash seeds were broadly seed vivipary phenomenon,that is,the seeds were germinated in the seed fruit when they were removed from the parent organ.2.In this experiment,there were significant differences in the vivipary of different summer squash inbred lines.And this indicated that the vivipary characteristics of summer squash seed was related to types of plant genotype.3.In this experiment,in 35-day old seed fruits and different after-ripening time,there are not observed in the processing of seed vivipary,and in the seed fruit age of 45 days and after-ripening time of 30 days,50 days and after-ripening time of 20 days and 30 days were observed in the processing of high vivipary rate.Therefore,the physiological ripening of fruits and seeds is a prerequisite for the vivipary of summer squash seeds.And the vivipary rate of inbred line F,which is prone to vivipary seed,rises with the increase of seed ripening and seed maturity.4.In this study,paraffin section technique was used to compare the seed coat anatomical structures of the squash materials F,B-2 and the Chinese pumpkin L0.The seed coat of F and B-2 of the two summer squash lines with different seed vivipary characteristics were five layers of tissue cells,that is,the epidermis,the hypodermis,the sclerenchyma,the parenchyma and the chlorenchyma,in which the sclerenchyma and the parenchyma are more lignified,forming a hard seed coat.And the structure of their was not observed significant differences;Chinese pumpkin material L0 can clearly see the three layers of tissue cells,that is,the epidermis,the hypodermis,the sclerenchyma,the parenchyma and the chlorenchyma,and part of the epidermal cells protruding outward to form epidermis hair.And to a certain extent,epidermis hair and thicker sclerenchyma may hinder the absorption and respiration of pumpkin seeds.The above analysis shows that the seed coat structure does not lead to the direct difference of seed vivipary characteristics of summer squash,but the seed coat structure may be one of the causes of the difference between the summer squash material F and the Chinese pumpkin L0.5.In this study,the contents of endogenous hormones in different parts of seed fruit were quantitatively determined by triple quadrupole LC-MS.The results showed that:(1)Seed fruits and seeds have not yet reached the physiological maturity in 45-day old,and in different after-ripening time,although there was a significant difference between GA and ABA metabolic levels and GA/ABA values in the seeds of material F,which were prone to seed vivipary,and the seeds of B-2,which were not prone to seed vivipary,there was no occurrence of seed vivipary.(2)The ABA content in F seeds was significantly lower than that of B-2,and the GA/ABA in F seeds was significantly higher than that in F-seed B-2,indicating that F can occur in the seed embryo may be related to the decline in ABA content and higher GA/ABA value.(3)In different after-ripening time,The GA/ABA values of seeds in 50-old fruit F were higher than those of 45 days.And in the seed fruit age of 45 days and after-ripening time of 30 days,50 days and after-ripening time of 20 days and 30 days,there were observed in the processing of high vivipary rate.These indicated that higher GA/ABA in the seed value could be the main factors of seed vivipary.