Effect Of Potassium On Root Physiological Characteristic And It's Regulation Mechanism In Winter Wheat

Using two typical cultivars Yannong 15 and Lumai 22, with soil culture and solution culture, the study was made to explore that under the condition of K-deficiency the effect of different levels potassium fertilizer on winter wheat root and aerial part growth, the effect on root physiological characteristic such as root activity, root NR activity, soluble sugars content and hormones concentration in root eth, and the effect on grain yield and protein synthesization, the main result are as followed:1 A good supply of K could promote the growth of root fresh weight and accumulation of aerial part dry matter. K-deficiency also can make wheat bloomed ahead of schedule and growth period shorter. Supply of K can increase the area of flag leaf and slower the rate of decline of SPAD of leaf, which is propitious to the photosynthesis of flag leaf and grain filling. But K has no remarkable effect on wheat seeding under condition that K is sufficient for wheat seeding.2 K-deficiency can reduce accumulation of dry matter of aerial part. However, the contribution of stem and sheath reserves to ear is bigger than the treatments with supply of K. That reason may be that potassium fertilizer promote carbohydrate synthesize so increase of grain weight less depend on the contribution of stem and sheath reserves to ear than control treatment. 3 Good supply of potassium fertilizer to K-deficiency soil can promote the absorption of N and translocation to grain. Supply of potassium has little effect on absorption of P in Yannong 15 and promote the absorption of P in Lumai 22 lightly. Supply of potassium fertilizer promote K absorption and potassium content of plant remarkably except for grain because the potassium and phosphor content of grain don't change with different levers of potassium supplied. 4 Root activity of wheat reach max then decline rapidly and decline slowly during grain filling. The effect of K on root activity is remarkable before anthesis. Treatments with supply of potassium improve root vigor remarkably. 5 Appling potassium fertilizers can increase the concentration of (Z+ZR), GA3, IAA in wheat root and flag leaf, decrease the ABA content of root and leaf, which may be a reason for that flag leaf SPAD of treatments with potassium decline slower than that of control treatments. Appling potassium can prominently reduce ABA content in grain on grain filling anaphase and increase the GA3 content of grain.6 The total soluble sugar content of stem and sheath in control remain very low during grain filling and applying potassium fertilizer in the soil of K-deficiency can significantly increase the soluble sugar content in root. However, the effect of potassium on soluble sugar in stem and sheath of Lumai22 is more remarkable than that of Yannong15.7 Potassium promote N absorption and assimilation in flag leaf, for applying potassium fertilizer can promote the NR and GS activity in flag leaf, which are key enzyme in N metabolize. Potassium can significantly promote the protein accumulation amount in grain. Potassium can increase protein content of grain in Lumai22 and have less effect on grain protein content of Yannong15.8 Applying potassium fertilizer can promote the soluble sugar content in grain and flag leaf during grain filling, which indicate that the carbohydrate synthesize is promoted. Potassium can also increase amylose content and reduce amylpectin content but have little effect on total starch. 9 Applying potassium fertilizers increase the yield of two cultivars remarkably. Applying potassium increase kernel weight mainly in Lumai22 while potassium increase kernel weight and kernel per spike in Yannong15. The result also shows potassium fertilizer has greater effect on Yannong15 than Lumai22.