Maize is widely planted throughout the world and has the highest yield of all the cereal crops. The arid region of Northwest China has become the largest base for seed-maize production, but water shortage is the bottleneck for its long-term sustainability. Investigating the transpiration of seed-maize plants will offer valuable information for suitable planting and irrigation strategies in this arid area. In this study, stem flow was measured using a heat balance method under alternate furrow irrigation and double-row ridge planting. Meteorological factors, soil water content(θ), soil temperature(Ts) and leaf area(LA) were also monitored during 2012 and 2013. The diurnal stem flow and seasonal dynamics of maize plants in the zones of south side female parent(SFP), north side female parent(NFP) and male parent(MP) were investigated. The order of stem flow rate was: SFP>MP>NFP. The relationships between stem flow and influential factors during three growth stages at different time scales were analyzed. On an hourly scale, solar radiation(Rs) was the main driving factor of stem flow. The influence of air temperature(Ta) during the maturity stage was significantly higher than in other periods. On a daily scale, Rs was the main driving factor of stem flow during the heading stage. During the filling growth stage, the main driving factor of NFP and MP stem flow was RH and Ts, respectively. However, during the maturity stage, the environmental factors had no significant influence on seed-maize stem flow. For different seed-maize plants, the main influential factors were different in each of the three growing seasons. Therefore, we identified them to accurately model the FP and MP stem flow and applied precision irrigation under alternate partial root-zone furrow irrigation to analyze major factors affecting stem flow in different scales.
BO Xiao-dongDU Tai-shengDING Ri-shengTONG LingLI Si-en
Scientific irrigation and nitrogen management is important for agricultural production in arid areas. To quantify the effect of water and nitrogen management on yield components, biomass partitioning and harvest index(HI) of maize for seed production with plastic filmmulching, field experiments including different irrigation and N treatments were conducted in arid north-west China in 2013 and 2014. The results indicated that kernel number per plant(KN) was signi ficantly affected by irrigation and N treatments. However, 100-kernel weight was relatively stable. Reducing irrigation quantity signi ficantly increased stem partitioning index(PI_(stem)) and leaf partitioning index(PIl_(eaf)), and decreased ear partitioning index(PI_(ear)) at harvest, but lowering Nrate(from 500 to 100 kg N$hm^(–2))did not signi ficantly reduce PI_(stem), PI leaf, andPIl_(eaf) at harvest. HI was signi ficantly reduced by reducing irrigation quantity, but not by reducing Nrate. Linear relationships were found between KN, PI_(stem), PI leaf,PIl_(eaf) at harvest and HI and evapotranspiration(ET).
Hui RANShaozhong KANGFusheng LILing TONGTaisheng DU
Understanding of hydrological processes,including consideration of interactions between vegetation growth and water transfer in the root zone,underpins efficient use of water resources in arid-zone agriculture.Water transfers take place in the soil-plant-atmosphere continuum,and include groundwater dynamics,unsaturated zone flow,evaporation/transpiration from vegetated/bare soil and surface water,agricultural canal/surface water flow and seepage,and well pumping.Models can be categorized into three classes:(1)regional distributed hydrological models with various land uses,(2)groundwater-soil-plant-atmosphere continuum models that neglect lateral water fluxes,and(3)coupled models with groundwater flow and unsaturated zone water dynamics.This review highlights,in addition,future research challenges in modeling arid-zone agricultural systems,e.g.,to effectively assimilate data from remote sensing,and to fully reflect climate change effects at various model scales.
