| This experiment was conducted in 2014-2016 at the Technological Innovation Center of Maize in Huang-Huai-Hai Region and the Stage Key Laboratory of Crop Biology,located at Shandong Agriculture University inTaian.High-yield corn cultivar Zhengdan 958(ZD958,the sallow one)and super high-yield corn cultivar Denghai 661(DH661,the deep one)with different root system architecture were chosen as experiment materials and the experiment was conducted in field and green house.At the bugle stage of corn planted in field,roots of different cultivars were cut vertically at both sides of plant along to the planting rows at different horizontal distance of 10 cm,20 cm,30 cm in a 60 cm depth and no root cutting was set as control,marked T-10,T-20,T-30,CK,respectively.In green house,roots were cut vertically at both sides of plant along to the planting rows at different horizontal distance of 10 cm,15 cm,20 cm in a 60 cm depth and no root cutting was set as control,marked T-10,T-15,T-20,CK,respectively.Effects of vertical root cutting on leaf photosynthesis in reproduction stage and grain yield under field condition and changes of leaf photosynthetic performance in a short period after root excision under green house condition were investigated.We want to provide the theoretical support to selecting optimal root architecture and further improving the grain yield by understanding the role of root in different soil played in regulating the leaf photosynthesis and yield.The main results as follows: 1 Effects of vertical root cutting at different horizontal distance on root system of summer maize cultivar with different root architecture systemRoot of DH661 concentrates in the soil profile on a scale of 0 cm to 10 cm to plant center and tighter than ZD958 in horizontal.Roots cutting at the distance of 10 cm to the plant center decreases the root dry weight,root length,root volume,root surface area by 16.82%,30.45%,31.26%,33.56% respectively,and reduction rate of these index were 7.52%,8.83%,6.15%,8.51,respectively when the roots were cut at the distance of 20 cm for DH661.For ZD958,the reduction were 24.81%,48.83%,46.15%,43.15% respectively at the distance of 10 cm,and 13.12%,37.12%,35.65%,34.03% respectively for 20 cm.The reduction rates of root parameters of ZD958 were larger than those of DH661.2 Effects of vertical root cutting at different horizontal distance on leaf photosynthetic performance of summer maize cultivars with different root architecture systemThe leaf area index(LAI),leaf chlorophyll content,stomatal conductance(Gs),transpiration rate(E),net photosynthetic rate(Pn),and intercellular carbon dioxide(Ci)in early stage were decreased,but Ci in later stages were increased by vertical root cutting.Effects of root cutting on these indexes were relative to the site of root cutting and cultivar.The smaller the distance of root cutting site to the plant center,the greater effects of root cutting on these indexes were.Changes of these indexes of ZD958 were greater than DH661 when their root were cutting in same place.Gs,Pn,Ci,the performance of donor(WK)and acceptor side(VJ)of PSII,light of absorbed(ABS),captured(TR),and used to transport electron(ET)by PSII were decreased by root cutting in a short period after root excision.These indexes reduced more when the roots were cut in a small distance to plant center.Leaf photosynthetic performance in root cutting treatments could recover to some extent but still lower than CK.The time that plant need to recover is depends on the extent of root excision.It will take a long time if the site is near to the plant center.3 Effects of vertical root cutting at different horizontal distance on plant nutritional status of summer maize cultivars with different root architecture systemThe NPK accumulation amount of plant and N accumulation amount of leaf were reduced by root excision and the amount of the N translation of leaf increased.At R6 stage,the total N accumulation amount,the total P accumulation amount,the total K accumulation amount of T-20 of DH661 were decreased by 9.45%,20.19%,14.67% respectively and 13.92%,22.19%,27.64% for T-10.For ZD958,the total N accumulation amount,the total P accumulation amount,the total K accumulation amount of CK were higher 9.45%,20.19%,14.67% than T-20,and 22.54%,21.61%,30.45% than T-10.The the N translation of leaf from VT to R6 shows such a trend that T-10 > T-20 > T-30 > CK.The utilization of soil resource was effected by root cutting and the residues of NPK in soil resulted from the decreasing of plant absorbing amount in root cutting treatments were higher than control.4 Effects of vertical root cutting at different horizontal distance on leaf water status of summer maize cultivars with different root system architectureRoot excision has an important effect on leaf water status.The relative leaf water content of T-30,T-20,T-10 of DH661 were decreased by 1.56%,11.21%,13.68%,respectively at VT stage,and 2.10%,12.99%,15.00% respectively at R6 stage.For ZD958,reduction rates of T-30,T-20,T-10 were 6.90%,13.44%,17.33% at VT stage and 7.33%,18.11%,19.34% at R6 stage respectively.The leaf water potential of T-30,T-20,T-10 of DH661 were decreased by 8.52%,11.82%,29.40%,respectively at VT stage,and 2.95%,22.29%,31.12% respectively at R6 stage.For ZD958,reduction rates of T-30,T-20,T-10 were 6.80%,13.35%,22.95% at VT stage and 9.14%,19.67%,22.44% in R6 stage respectively.The nearer the root cutting site to the plant center,leaf water status is more serious.The leaf water status was more serious in ZD958 than DH661 when the roots were cut at the same distance to plant center.5 Effects of vertical root cutting at different horizontal distance on biomass and yield of summer maize cultivar with different root architecture systemBiomass and yield of different summer maize cultivars were reduced by vertical root cutting and the effects of root excision on them was relative to the distance of cutting site to the plant center.Biomass and grain yield decreased by 7.36%,4.64% in 2014 and 6.05%,5.02% in 2015 in T-20 of DH661,while 11.84%,11.01% in 2014 and 9.81%,10.72% in 2015 for T-10.The reduction rates of biomass and yield for T-20 of ZD958 were 10.66%,9.11% and 9.92%,8.14% in two years.For T-10 of ZD958,the reduction rates of biomass and yield were 16.00%?13.37% and 14.72%?14.82%.Roots which concentrate in the soil ranging from 0 to 10 cm to plant center played a more important role in biomass and yield to DH661 than ZD958. |
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