Stdudy On Tillering Characteirstics And The Regulation Of Different Type Maize Varieties

The experiment was carried out from2008to2011in Shandong Agricultural Universityexperimental farm. Mexican (MXG) and KeDuo8(KD8) and KeDuo4(KD4) andWuYue97-1(WY97-1) and ZhengDan958(ZD958) were used for experimental materials.The treatments of different sowing date and plant density and exogenous hormone were setup to study the tillering characteristics and the regulation of different maize varieties. Themain results and conclusions as follows：1. Tillering characteristics of different maize varietiesThe results showed that tillers were co-elongated with leaves of main stem, the numberof primary tiller (n) and leaf age of main stem (N) had the relationship of n=N3, thesecondary tillering had the same relationship as the primary one. Tillering ability showedsignificant differences among different maize varieties, Mexican’s tillering ability was thestrongest, the maximum tiller number was about25-40, and Keduo4was about2-4and thenWuyue97-1was about1-2, however, Zhengdan958had no tiller in general.2. Influences of different regulation measures on tillering characteristics ofmaizeThe tillering ability of maize was affected by sowing date and plant density. Highertemperature and sunlight and lower plant density were favorable to tiller’s development. Withthe postponement of sowing date, the interval from seeding to tillering became shorter, thegrowth of tiller’s leaves became quicker, and the maximum tiller number was increased.When sowed on25April and25June at4.50×104plant·ha-1population, the maximum tiller number of the Keduo4was3.50and4.00while the ultimately tiller number was2.33and2.00, respectively, so the eliminating rate of tiller was33.4%and50.0%respectively. Thesimilar changes were observed in3.00and6.00×104plant·ha1populations.With the increment of plant density, tiller’s occurrence was postponed, and the leaf agesdecreased on same day after emergence of seedling, tiller number of main stem with the sameleaf age and the maximum and ultimately numbers reduced, the tillers’ eliminating rateincreased. When sowed on25April, taken the3.00and4.50and6.00×104plant·ha1populations, the maximum tiller number was3.80,3.50and3.22, and ultimately tiller numberwas3.00,2.33and1.67, so the eliminating rate was21.05%,33.43%and48.14%,respectively.The6-BA treatment had increased the maximum and ultimately tiller number of differentmaize varieties and accelerated the tillering speed; however, the GA treatment had theopposite effect. The effects of spraying6-BA in leaves are much more than those of seedsoaking.3. The tillering mechanism of different maize varieties3.1Effects of endogenous hormones on tiller development process of different maizevarietiesThe tillering capacity of different maize varieties was controlled by both the content andthe ratio of endogenous hormones in basal stem and functional leaves. During the tilleringstage, the ZR (zeatin riboside) content was higher and appeared an increasing trend, however,the IAA (indole-3-acetic acid), ABA (abscisic acid) and GA (gibberellin acid) contents werelower and appeared a decreasing trend in basal stem and functional leaves. The ratios ofIAA/ZR and ABA/ZR were lower when tillering and higher at the end of tillering stage. TheZR content of MXG was higher and IAA, ABA, GA, IAA/ZR, ABA/ZR were lowerrespectively.With the postponement of the sowing date, the ZR content in basal stem and functionalleaves increased during tillers generation and decresed during tillers perishment, while thechanging regulation of IAA, ABA and GA was the exact opposite, and the ratio of IAA/ZRand ABA/ZR of basal stem and functional leaves decreased during tillers generation and increased during tillers perishment. With the increment of plant density, the ZR content inbasal stem and functional leaves reduced while IAA, ABA and GA content and the ratio ofIAA/ZR and ABA/ZR increased. Tillering emergence was promoted by high optothermal andlow density while it was inhibited by low optothermal and high density. The ZR promotedtillering and IAA, ABA and GA suppressed tillering.3.2The study of tillering microstructure of different maize varietiesThere were tiller buds in tillering nodes of all different maize varieties. The tllers growedbetter and had stronger superiority and the ratio of diameter and dry matter of tiller/main stemwere higher of the variaties which with stronger tillering ability. So the tillers buds would beindependent tillers and be still alive at last, the variaties with weaker tillering ability were onthe contrary. So if the tiller buds would be independent tillers depended on the ratio oftiller/main stem, the higher ratio was benefit to tiller buds to be tillers.