Effect On Stalk Lodging-resistance Characteristics And Photosynthetic Characteristics By Different Types Of Maize Cultivar Under High Density

The experiment is set with the potential cultivars in increasing yield of Xianyu335, Neidan314and Zhengdan958, and low density but large panicle cultivars of Shendanl6, Sidan19, Xundan20, Neidan205and Kehe8. Searching for the response of stalk lodging characteristics and photosynthetic characteristics of different types of maize cultivar are under the densities of7.50×104,9.75×104and12.00×104plant/hm2. The results are as follows:(1) The experiment materials can be divided into two categories according to cluster analysis of stalk trait indicators and yield trait indicators. Category I:Xianyu335, Neidan314and Zhengdan958, which is strongly in lodging-resistance and high yield. Category II:Shendanl6, Sidanl9, Jundan20, Neidan205and Kehe8, which are weak in lodging-resistance and low yield.(2) Under high density condition, stalk agronomic traits performance that ear height, stem diameter, unit length of the dry matter weight, stem wall thickness and cellulose amount are high. Mechanical characteristics of stalk performance that puncture strength, the crushing strength and break intensity are reduced. The unit length of the dry matter weight, stem wall thickness, cellulose amount and mechanical characteristics of stalk are closely related to stalk lodging-resistance characteristics which are the most important indicators to evaluate stalk the ability of lodging-resistance.(3) Under high density conditions, the anti-photosynthetic indicators LAI and Fo were increased, while LAD, NAR, SPAD, Tr, Ci, Pn, Fv/Fm and Fv/Fo were decreased. Tr, Pn, Fv/Fm and Fv/Fo performance upper leaf> ear leaves> lower leaves, while Ci and Fo performance lower leaves> ear leaf> upper leaves. Regarding to SPAD, strong lodging-resistance cultivars performance ear leaves> lower leaves> upper leaves, while weak lodging-resistance cultivars performance ear leaves> upper leaves> lower leaves. Strong lodging-resistance cultivars’Tr and Pn of upper leaves and lower leaves are higher, while Ci is lower comparing to weak lodging-resistance cultivars; LAI, LAD, Fv/Fm and Fv/Fo are lower, while NAR and Fo are higher.(4) As density increasing and soil depth deeply, root dry matters become decrease in different types of maize cultivars, but the range gradually reduced. Comparing to weak lodging-resistance cultivars, strong lodging-resistance cultivars" root dry matters are bigger in10-50cm soil depth and the decreasing trend is slow.(5) Grain number per ear,1000-grain weight and ear setting rate decreased under high density. As strong lodging-resistance cultivar, grain number per ear is lower but1000-grain weight and ear setting rate are higher, this is the reason to high yield under high density.