| Potassium is one of the essential macronutrients for corn., it closely related to the lodging resistance and yield formation of the crop. Former research on effect of potassium application on potassium utilization and yield of Maize was limited to the north area, the study on the southwest area was less and there was no relevant report particularly in hilly area of central Sichuan Basin. And, in the aspects of the influence of potassium application on lodging resistance ability of maize, the comprehensive research on the effects of potassium application rates on internode morphology, dry matter, chemical composition, mechanical properties and grain yield was less. The optimum application of potassium fertilizer when achieve high yield and the best corn lodging resistant ability was unknown. Therefore, Zhenghong505, which was one of the largest application varieties in hilly area of central Sichuan Basin and recommended by Sichuan Provincial Department of Agriculture, was used in the experiment in 2013-2014. By comprehensive study the effects of different application of potassium fertilizer on potassium utilization, stem morphological characteristics, characteristics of dry matter accumulation, stem physiological characteristics, stem mechanical properties and yield of corn, to reveal the potassium utilization rule and the lodging mechanism, and to put forward the optimum application of the potassium fertilizer at the same time. Besides, aimed at provided the theoretical basis for realize high yield cultivation of lodging resistance and the scientific management of potassium fertilizer. The main results showed as follows:1. The suitability of the potassium fertilizer plays an important role in dry matter accumulation of maize. Big trumpet period, K1, K2, K3, K4 treatment for two years on average, compared respectively with the control (K0) increased 10.1%,26.9%,33.8% and 37.3%. After the silking stage, the dry weight increase first and then decrease with the increase of potassium and the K2 deal was the highest. The silking stage, filling stage and maturity stage of K2 treatment for two years on average, compared respectively with the control (K0) increased 17.1%,32.4% and 19.6%. Dry matter accumulation started to decline when the potassium application rate more than K2. Potassium fertilizer levels on the potassium content in various organs of each period also have different degree influence. In general, each organ and whole plant potassium content increased along with the potassium level increasing and the K4 deal was the highest. The larger effects are on vegetative organs, especially in stem and sheath, effects on the reproductive organs are relatively small. The maturity stage, K1,K2, K3, K4 treatment for two years on average, the potassium content of stem and sheath were increased by 24.5%,29.7%,27.4%,43.5% compared with the control (K0), potassium content of leaves were increased by 9.2%、24.1%、 19.7%、29.0% and the whole plant potassium content were increased by 12.4%、15.9%、19.1%、 25.4%. Because the potassium level not only affects the plant potassium content of corn, but also affected the dry matter accumulation, which can significantly affect the plant potassium accumulation of each period. Before the silking stage, plant K accumulation increased with the fertilizer level increasing and the K4 deal was the highest. But it increased first and then decreased with the increasing of potassium fertilizer after spin and the highest is K2 deal.2. The results show that agronomic efficiency of K is increased at the first, and then gradually decreased with the increment of the K application rates and the K2 deal is the highest. In addition, potassium agronomy efficiency in K4 appeared to nearly zero, that Indicates excessive decreased potassium transfer from vegetative organs after anthesis to grain. As applied K increased, K physiological efficiency, K utilization efficiency and K recovery efficiency decreased. Besides, K uptake efficiency, K fertilizer efficiency and partial factor productivity from the applied K are reduced significantly, but K harvest index did not affect significantly. K translocation amount, K translocation efficiency and K contribution proportion are all decreased with the increment of the K. application rates. K4 treatment for two years on average, K translocation amount, K translocation efficiency and K contribution proportion i decreased 88.4%,88.1% and 88.0% compared with the maximum value treatment Kl. K absorption of seeds increased slightly and the increment rate decreases gradually with the increment of the K application rates. It illustrates that increment of the potassium supply does not further increase the uptake of potassium in Maize grain when K absorption of seeds to a certain extent.3. At silking stage, the third internode’fresh weight and dry weight under 4 fertilizer treatment (K1-K4) were increased by 19.65%,22.67%,33.32%,38.00% and 9.41%,7.88%,15.75%,13.35% compared with the control (K0), fresh density and dry density were increased by 11.41%,11.82%,14.59%,13.57% and 8.67%,6.03%,6.55%,0.32%, the trend is consistent with other internodes, filling stage and silking stage consistent with the basic law. It shows that the amount of potassium fertilizer can improve the internodes’ weight and plumpness.4. All internodes stalk crushing strength and lodging rate showed significant or extremely significant negative correlation at silking and filling stage. With K fertilizer (x) as the independent variable, the third and fourth internodes’ average stalk crushing strength(Y) as the dependent variable, the mechanical effect equation for Maize are Yss=247.66+0.587x-0.0027x2(R2=0.8744**,2014) and Yfs=228.51+0.760x-0.0035x2(R2=0.8289**,2014). So, the application of potassium fertilizer are 108.70kg/ha and 108.57kg/ha when reach the maximum stalk crushing strength at silking stage and filling stage.5. Grain yield increase of first and then decrease with the increment of the potassium application rates and the K2 had the highest yield. The grain yield under K2 were increased by 737.3 kg/ha and 800.1 kg/ha compared with control (K0) in 2013 and 2014, an increase of respectively 8.4% and 9.2%. Yield does not continue to increase under excessive potassium, but decrease. The grain yield of K3, K4 in 2013 and 2014 were decreased by 3.9%,6.7% and 4.5%, 6.8% compared with the maximum value treatment K2. Through the two curves (Y=a+bx+cx2) to simulated the relationship between the grain yield of maize and the potassium application rates, we get the quadratic equation with one unknown of potassium efficiency are Y=8691.9572+12.5575X-0.065303X2(R2=0.7410**)and Y=8690.7339+13.5201X-0.071116X2(R2=0.7516**) in 2013 and 2014. As can be seen, the grain yield increased with the increment of the K application rates and changes in variation of parabola with downward openings. And the maize reached its highest yield of 9295.65 kg/ha and 9333.32 kg/ha in the potassium application of 96.15 kg/ha and 95.06 kg/ha in 2013 and 2014.The results found that the yield for putting the potassium application where the corn reached the strongest lodging resistance to the potassium fertilizer effect equation and the highest yield were no significant differences. |
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