Characteristics Of Sugar Accumulation And Transport In The Sequential And Non Sequential Senescence Of Wheat

Sequential senescence wheat is a wheat which senescence according to the order of leaf development, the flag leaf senescence at last. Non sequential senescence wheat is a wheat that his flag leaf is first senescence than the second at final grain filling stage. In order to proven wheat sequential and non sequential senescence of physiological and biochemical mechanisms and in production application value, the comparative study of the two types of senescence wheat top two leaves, sheath in the middle and final grain filling stage photosynthetic rate, soluble sugar, sucrose and glucose transport key enzyme activity variation and relationship with grain yield, in order to provide a academic basis for the breeding of wheat varieties. The main conclusions of this paper are as follows:1.Compared with the sequence senescence wheat, non sequential senescence wheat Lankaoaizao8 flag leaf has significantly higher net photosynthetic rate, and non-sequential senescence wheat Wenmai 19 flag leaf net photosynthetic rate slightly higher than the sequential senescence wheat, the difference is not distinct. The net photosynthetic rate of the non sequential senescence wheat two leaves, however, was significantly higher than sequential senescence wheat in the late grain filling stage. To sum up, the top two leaves of non sequential senescence wheat had higher net photosynthetic rate.2. The Soluble sugar and sucrose content in flag leaf and second leaf of wheat cultivars showed the first increase and then decreased at 15-30 d after anthesis, and the maximum value appeared at 20 d or 25 d after anthesis. The soluble sugar and sucrose accumulated in the flag leaf and the second leaf of the non sequential senescence wheat were significantly higher than sequential senescence wheat. Sequential senescence wheat Xinong 88 and nr9405 flag leaf and second leaf soluble sugar peak respectively 106.68 and 97.39 mg/g DW, of 48.93 and 60.19 mg/g DW. Rather than sequential senescence wheat Wenmai 19 and Lankao Aizao 8 flag leaf and second leaf soluble sugar peak respectively 224.33 and 242.6 mg/g DW, 149.18 and 142.71 mg/g DW. Therefore, the accumulation of soluble sugar in Flag Leaf during late grain filling is the main reason for the non-sequential senescence of wheat leaf. A large amount of soluble sugar was transported from the leaves to the grains during the non sequential senescence of the leaves, It is in favor of the late grain filling.3. In15-30 d after anthesis, in the leaf sheath, a mount of soluble sugar and sucrose content is decreased. Compared with the sequence senescence wheat, non sequential senescence wheat flag leaf sheath, the second leaf sheath in the accumulation of soluble sugar and sucrose was significantly higher than the sequential senescence wheat. At the final grain filling stage, the sequential senescence wheat Xinong 88 and nr9405 flag leaf sheath, the second leaf sheath soluble sugar translocation to grain weight respectively for DW 39.32,49.65,61.55,56.46 mg/g. And non sequential senescence wheat Wenmai 19 and Lankaoaizao 8, the soluble sugar translocation to grain weight of top two leaf sheath respectively DW 92.99134.55,89.36142.29 mg/g, non sequential senescence wheat flag leaf sheath, the second leaf sheath soluble sugar turn volume was significantly higher than the sequential senescence wheat, which is conducive to the late filling grain weight increase.4. In 15-30 d after anthesis, the activities of SS and SPS in wheat cultivars showed a trend of first increasing and then decreasing. Compared with the SS and SPS activity of sequence senescence wheat the non- sequence senescence wheat leaf and sheath were higher order. The SS and SPS activity of leaf and sheath and sucrose content has a significant positive correlation. Therefore, high activity of SS and SPS in leaf and sheath, conducive to the synthesis of sucrose, soluble sugar to promote grain transport.5. The non-sequential senescence wheat was significantly higher than sequential senescence wheat in ear weight, grain weight and 100 kernel weight.