Studies On The Effects Of S-3307 Applied To Seed On Leaf Senescence Of Wheat

The effects of S-3307 (Uniconazole) applied to seed with different concentrations (0.. 5-. 10.. 20.. 40-. 80mg/kg) on leaf senescence of wheat c.v. (Chuanmai30 and 89-107) were studied. The results were showed as flows: l.S-3307 treatments decreased the length and leaf area of 1-9 leaves, while it increased the length and leaf area of the flag leaf and the reciprocal second leaf. The main stem leaf area for S-3307 treatments in 89-107 was significantly lower than that of control, the higher of the concentration, the less of the main stem leaf area. While Chuanmai30 had no significant difference in main stem leaf area for S-3307 treatments except 80mg/kg. S-3307 increased the amount of main stem leaves, Chuanmai30 had more 1.1 leaves than that of control, 89-107 had more 0.8 leaves than that of control. S-3307 increased the dry weight per unit leaf area during the leaf senescence. 2.S-3307 treatment increased the chlorophyll and soluble protein contents in the leaves during leaf senescence, and increased chlorophyll a/b ratio. The N content and water content in leaves for S-3307 treatments were higher than that of control in senescence lateral period. All of these delayed leaf senescence. 3.The accumulation speeds of dry matter in S-3307 treatment leaves were faster than in control leaves. S-3307 treatments had more carbohydrates and their transportation speeds were faster than control s, The C/N ration was reasonable, which accelerated the grouting speed and prolonged the grouting process. 4.Ln the meanwhile, the activities of SOD(superoxide dismutase) CAT(catalase).. APX(ascorbate peroxidase) were increased for S-3307 treatments, 44 the MDA content was decreased during senescence. At the same time, the activities of RNase were decreased. 5.5-3 307 treatment increased grain number per ear significantly, and increased the 1000-grain weight also. So, 5-3307 treatment increased yield significantly. The 20mg/kg S-3 307 concentration got the best result, the grain yield increased by 1095kg and 858kg per bin2 on Chuanmai30 and 89-107 respectively. Therefore, it was suggested that the action of S-3 307 on delaying senescence of wheat leaves was correlated with the increasing activities of active oxygen scavenging system, and the decreasing activity of RNase. The physiological mechanisms of S-3307 to increase grain yield may be due to the increase of photosynthetic area, photosynthetic rate and photosynthetic period.