Effects of different ethephon applications on agronomic traits and grain yield of maize
Two field experiments of ethephon-brushed leaves of Zhengdan 958 and ethephon-sprayed topmost canopy of Xundan 20 were carried out, and the percentage decline of each main internode length relative to respective check was employed to the measurement of the shortened degree. The results revealed that ethephon had internode-cascaded and additive inhibition elongation effects on the elongating internodes or several ones above them. When ethephon solution was sprayed on the topmost canopy of maize at the stage of "n" expanded leaves, which showed that the elongation-inhibited internodes were the several ones above the(n-2)th node, especially, the length between the(n-1)th and the(n+4)th internode was shortened obviously, and the length of the(n-1)th or the(n)th internode was usually shortened most; on the whole, percentage decline of respective internode length above the(n+4)th internode was obviously decreased with its step-up node, but except the tassel internode. Leaf age index between 55 and 70 is the best ethephon-sprayed stage for Xundan 20, which increase the ability of lodging and breaking resistance significantly; and the appropriate dosage should be decided by achieving no less than 95% kernels and leaf area of the check.