Effects of Cultivation Types on Yield Formation and Nitrogen Accumulation and Remobilization for Winter Wheat

A field experiment was conducted to study the effects of cultivation types on grain yield,dry matter accumulation and translocation,nitrogen uptake and remobilization of winter wheat at 240 kg N·hm-2 on dryland soil in southern region of the Loess Plateau from 2002 to 2003.Five treatments,plastic film mulching,straw mulching,supplemental irrigation,ridge-furrow cultivation and control(no mulching on soil surface and no supplemental irrigation),were designed.The results showed that plastic film mulching could significantly increase tillers at jointing stage,enhance dry matter accumulation in the aboveground part during the whole growth stage,and promote the contribution of pre-heading assimilation from vegetative parts(stem and leaf) to ears,therefore improve the biomass and grain yield.At the same time,winter wheat could uptake more N under plastic film mulching,and N translocation from stem and leaf to ears was enhanced after heading.Nitrogen from vegetative parts could account for 86.3% of that accumulated in the ears.On the contrary,dry matter accumulation and N uptake were significantly lowered under other four cultivation types.Furthermore,dry matter accumulated in ears was mainly from the carbohydrate assimilated in the stem and leaf after heading,and N translocated from the vegetative parts played a less important role,compared to the plants grown in the plots with plastic film mulch.