Effect Of Different Water Conditions And Tillage Practices On Root Growth And Water Use Of Winter Wheat And Summer Maize And Its Chemical Regulation

Water storage is a limiting factor for a sustainable development of agriculture in North China Plain (NCP). Water use efficiency (WUE) is closely related to root growth and distribution. Studies were conducted to1) examine root growth and distribution of winter wheat and summer maize using soil core method, root box and in situ scanning under different tillage practices and irrigation treatments;2) investigate the relationship between root density, dry matter accumulation, water consumption and yield;3) illuminate the regulation mechanism of plant growth regulator on root growth and water use efficiency. The main results summarized as follow:(1) Field study was carried out to examine the effect of different practices on root growth, water use and yield of winter wheat under rain-fed condition (WO). Plowing tillage (PT) promoted root growth of winter wheat before flowering compared with no tillage (NT) and increased yield and WUE. Compared with NT, PT promoted root growth and plant population establishment before flowering stage, thus increased spikes and grain yield. Under PT, grain yield was increased by10.6%and5.2%, in2011-2012and2012-2013winter wheat growing season, respectively. Tillage practices affected water consumption at different growing stages, but there was no difference between tillage practices for the total water consumption (ET). The PT had the highest WUE and it increased byl4.9%and7.3%compared with NT, in the two winter wheat growing seasons, respectively.(2) Combined with NT, irrigated wheat once at jointing stage (W1) increased WUE and grain yield. The root had a relatively rational distribution under W1+NT compared with the other combinations and photosynthetic capacity and contribution of photosynthates to grain is greater. ET under NT+W1was lower than the other combination while WUE of NT+W1is higher.(3) Uniconazole and Cycocel (HK-1) increased tillering capacity and root growth of winter wheat before winter, constrained the tillers after winter and increased spikes and grain yield and WUE. The HK-1increased root number, root diameter, root weight and root/shoot ratio at tillering stage before winter. The HK-1increased WUE and root growth at deeper soil profile (20-50cm) during the whole growth period.(4) Plowing tillage promoted root growth and nutrition delivery rate during the whole growing period, and increased yield and WUE of summer maize. As compared with NT, yield was increased by10.8%and9.9%under PT, in2011and2012, respectively. The PT increased root weight in the0-40cm soil layer during the whole growth period. The root length density and root surface area density were significantly increased in10-50cm soil layer, but there was no difference among tillage practices below60cm. At the same time, the delivery rate of NH4+, NO3-, P, K, Ca, Mg, Fe, Zn etc. in root bleeding sap was higher than that under NT.(5) Ethephon (Eth) applied at jointing stage restrained root growth and nutrition delivery rate. Eth restrained shoot growth, but significantly increased root/shoot ratio before V12. The grain yield and WUE were lower at lower plant density under Eth treatment compared with control. However, there was no significant difference in yield and WUE at higher plant density compared with control.