Characteristic Of Photosynthetic Products In Storage And Transportation Of High Harvest Index Brassica Napus L. In Different Habitats

Brassica napus L.is not only one of the most important oil crops,with rich nutrition,but is an source to edible oil.Because of the great import of edible oil dependency rate,high yield has been an important research topic in B.napus. Due to the special climatic conditions, the yield in Lin Cang(Yunnan province) is much higher than that in Yangtze River area. The present study showed harvest index might be one of the important factors restricting the high yield in B.napus, so we determined sucrose and starch contents, cell structure, activities of enzymes related photosynthetic product synthesis and decomposition of some materials to compare the differences of harvest index between Chongqing and Yunnan in the same year, to explain the reason of high yield in Yunnan and to describe the features of harvest index in both Chongqing and Yunnan.The research materials in 2014 were 38 lines with normal appearance and similar growth period from 321 experimental materials which came from all aroud china and the research materials in 2015 were 55 lines of 321 experimental materials which had significant difference in harvest index.The main conclusions are as follows:Here were some conclusions from the 55 types of B.napus in 2015 and 38 types of B.napus in 2014:(1)Sucrose content of B.napus in Yunnan was higher than Chongqing during the flowering period.It can provide adequate nutrients for plant growth in the late stage. The difference of sucrose content in different parts of B.napus in two places during helwingia period was not significant. The large number of branches and siliques caused lower sucrose content of stem and pod(including skin and seed) of the main sequence than Yunnan during harvest period.The decline of starch content from helwingia period to harvest period indicated that some of the starch was divided into sucrose for grain growth or to contribute to other forms of storage change. Pod stalk phloem relative area were higher than Chongqing during helwingia period, which is conducive to the transport of photosynthate.The sucrose synthetase(SS)and sucrose phosphate synthetase(SPS) in leaves and pod skin of B.napus in Yunnan was significantly lower than that in Chongqing. However, the acid invertase activity in leaves and horns was significantly higher than that in Chongqing, which is beneficial to the synthesis of sucrose.These characteristics are beneficial to the synthesis of sucrose and provide sufficient nutrients for the growth of grain, which also caused the super high yield in Yunnan.(2): Variety and growth environment had great influence on sucrose and starch content in different parts of B.napus, and had little influence on the oil content.(3)The content of sucrose and starch in seed was in inverse proportion with oil content.The activity of the other three enzymes in the pod skin was higher than that of the leaves, which showed that the photosynthetic capacity of pod skin was stronger than that in the leaves. The pod skin is the main photosynthetic organs of B.napus production.From two years and two places experiments of extreme harvest index B.napus we can know(1) the sucrose content and oil content in different parts of extreme harvest index B.napus of two places were the same. The sucrose content in stem and pod decreased gradually. The sucrose content and oil content increased gradually. The changes of starch content in B.napus were different in two places. Stem starch content in Chongqing increased firstly and then decreased and that in Yunnan decreased gradually. The starch content of B.napus pod skin and grain increased gradually in Chongqing, Yunnan was the opposite.(2)From the correlation analysis of harvest index we can know: The content of sucrose in different stages and parts of Chongqing low harvest index B.napus and Yunnan high harvest index B.napus were in the same direction as the harvest index. Chongqing high harvest index B.napus was consistent with the harvest index of Yunnan low harvest index B.napus. The degree of correlation was different, the specific reason is not clear. Correlation analysis of starch for two years obtained that the correlations of starch content and harvest index were basically the same in all parts of the high harvest index of B.napus, and the low harvest index B.napus had no obvious rules.(3) The relative area of Yunnan extreme harvest index B.napus pod stalk phloem, the activity of sucrose phosphate synthase, acid invertase activity and amylase activity were higher than those of Chongqing. This was the same as the overall mean, and the activity of sucrose synthase was different from that of the average.This is due to the higher contents of Chongqing high harvest index B.napus pod skin which raised the mean Chongqing B.napus pod activity of sucrose synthase(SS).Yunnan high harvest index B.napus had the following characteristics(1) During flowering and helwingia period, the leaf sucrose content of high harvest index B.napus was higher.The leaves’ ability to synthesize sucrose was stronger.(2) The lower starch content of each part during the helwingia period was beneficial to the transformation of carbon to sucrose, so as to provide sufficient nutrients for plant growth.(3) The difference of grain oil content was not obvious. Pod staik phloem relative area was high in the Helwingia period, which is conducive to the transport of Photosynthate.(4) The acid invertase activity was higher in the photosynthetic organs: leaves and the pod skin, which is conducive to the accumulation of sucrose. The amylase activity was lower, which may be related to the low starch content. The higher sucrose content in leaves may inhibit the activity of sucrose synthase and sucrose phosphate synthase. The lower sucrose content in the pod skin may be the reason for the high activity of sucrose synthase. Chongqing high harvest index B.napus had the following characteristics(1) The sucrose content in leaves of high harvest index B.napus was higher than that of low harvest index B.napus in Chongqing during the flowering and helwingia period.Sucrose content was low in pod skin during the helwingia period.(2)Seed oil content in the helwingia period was higher.During the harvest period,the difference was not obvious.(3)The pod stalk phloem relative area of high harvest index was lower, which is not conducive to the transport of photosynthate.(4) The activities of sucrose synthase, sucrose phosphate synthase and acid invertase were higher in photosynthetic organ: leaves and pod skin. Amylase activity was lower in the leaf, but the amylase activity in pod skin was higher, which is conducive to the degradation of starch sucrose for grain transport nutrients.