Effects Of Environment Conditions On Absorption And Distribution Of Silicon And Formation Of Bloom On Fruit Surface Of Cucumber

The bloom on fruit surface of cucumber(Cucumis sativus L.)is an importment index of commodity quality.There existed differences in bloom occurrence of cucumber grafted onto different rootstocks,and the differences still existed on cucumber with same rootstock and scion under different environment conditions.However,the mechanism of environment conditions affacting bloom formation on fruit surface of cucumber is still not clear.Therefore,'Yunnan figleaf gourd' with weak capacity of de-blooming and 'Huangchenggen No.2' with strong de-blooming capacity were selected as rootstocks grafted 'Shannong No.5' cucumber,and own-rooted cucumber was used as control in this paper.The effects of different environment conditions on bloom formation of fruit surface,silicon absorption and distribution,and the expression of silicon transporter genes in cucumber were investigated,in order to provide a theoretical basis for the production of high quality cucumber.The main results are as follows:1.The effects of different cultivation seasons(winter-spring crop;autumn-winter crop)in solar greenhouse on bloom formation on cucumber fruit surface were studied.The results showed that:(1)The amount of bloom on the surface of winter-spring cucumber fruit was significantly higher than that of autumn-winter crop.Cucumbers grafted on 'Yunnan figleaf gourd' possessed the maximum amount of bloom,which followed by own-rooted cucumber,while cucumbers grafted on 'Huangchenggen No.2' owned the minimum level.(2)There was no significant difference in the number of spheroids of bloom from fruit surface in different cultivation seasons during the period of 3 d before flowering.When the fruit matured,the number of spheroids of bloom from cucumber fruit surface and split degree of silicified layer on the spherical body surface in cucumber of winter-spring were significantly higher than those in autumn-winter.Under same cultivation season,the number of spheroids of bloom from cucumber fruit surface and split degree of silicified layer on the spherical body surface in 'Yunnan figleaf gourd' grafted cucumbers was the highest,followed by own-rooted,while 'Huangchenggen No.2' were the least.(3)The content of silicon in fruit and each organ and the relative expression of silicon transporter genes in cucumber leaves of winter-spring cucumber was higher than that of autumn-winter.The highest content of silicon was found in organs of 'Yunnan figleaf gourd' grafted cucumbers,followed by own-rooted cucumber and the lowest in'Huangchenggen No.2'.2.Simulating the environment conditions of solar greenhouses under different cultivation seasons in artificial climate chambers(T1:Day/night temperature 28/18 ?,relative humidity 55/65%,light intensity 600 ?mol·m-2s-1;T2:Day/night temperature 22/12 ?,relative humidity 85/95%,light intensity 300?mol·m-2s-1),and the effects of environment conditions on the absorption and distribution of silicon and the expression of silicon transporter genes in cucumber were studied.Results showed that:(1)The silicon content,total silicon absorption content in plants and distribution ratio of above-ground silicon of cucumber were higher in T1 than those in T2.Distribution ratio of silicon in the root system was the highest in cucumber grafted with 'Huangchenggen No.2',followed by own-rooted cucumber and lowest in 'Yunnan figleaf gourd' for the same environment conditions.(2)The relative expression of silicon transporter genes in cucumber leaves were higher under T1 than those under T2.Highest expression occurred on cucumber grafted onto'Yunnan figleaf gourd',followed by own-rooted cucumber,while lowest in'Huangchenggen No.2'.The root expression level was T1 lower than T2.