| Heilongjiang Province as a "strategic granary" and an important commodity food production base,its grain production capacity plays an important role in ensuring the security of food in China.Maize is one of the five major food crops in Heilongjiang.At present,maize has the largest contribution portion in the arrangement of crop structure and food production in the province.Due to the drought,short water,severe soil erosion,unreasonable irrigation of agricultural production and overexploitation of water resources,the water resources can not meet the demand of sustainable development of agriculture and ecosystem,which seriously restricts the development of maize industry in this area.RDI technology has been widely studied because it can regulate the proportion of Photosynthate products in various organs,and achieve the purpose of saving water and even increasing production.Ground drip irrigation,as an important water-saving irrigation technique,has great significance to increase crop yield and water use efficiency.The current study shows that crop water consumption of drip irrigation decreased by 25.9%,yield increased by11.6%,and water use efficiency increased by 49.9% compare to border irrigation.Compare to fine ground irrigation,drip irrigation has more obvious advantages in improving crop yield under the condition of insufficient irrigation.Therefore,this study intends to use regulated deficit irrigation and surface drip irrigation under the automatic induction shelter in Western Heilongjiang province,taking maize as the research object,with the method of micro-area test-pits in the field,to study the effect of RDI on dynamic growth indexes,water dynamic indexes,physiological indexes,yield and its components,crop water consumption and water use efficiency during the growing period of maize.In 2016 and 2017,the water deficit treatment was conducted at the seedling and jointing stage of maize,respectively.The upper and lower limits are controlled by the relative soil water content(percentage of field water capacity).The experiment set five different treatments(T1,T2,T3,T4,T5),which were mild at seedling stage(60%~70% FC),moderate at seedling stage(50%~60% FC),mild at jointing stage(60%~70% FC),moderate at jointing stage(50%~60%FC),and moderate at seeding combination with mild at jointing stage.In addition,set the whole growth period with suitable soil moisture content as contrast(CK).The test results are as follows:(1)Regulated deficit irrigation did not change the basic trend of the growth of maize roots and its crowns,however,there are some differences among different treatments.The plant height of all treatments showed rapid growth in the early stage,reaching the peak at the tassel period,andthen basically remain stable,and final average height of two-years increased by-20.6%~2.64%compare to CK.The stem diameter showed a rapid growth from seeding stage to jointing stage,later,there was no significant fluctuation,and final stem diameter of two-years increased by-20.36%~1.33% compare to CK.The leaf areas increased gradually,reached the peak in the filling stage,then decreased,showed the trend of inverted "V" types,and final leaf areas of two-years increased by-5.86%~27.46% compare to CK.The dry matter accumulation of maize crown and its roots showed a growth trend of "S" curve and inverted “V”curve,respectively.Its final dry matter increased-25.37%~1.26% and-5.94%~25.00% compare to CK,respectively.The same organs of maize crown showed the same growth trend,suitable water deficit is beneficial to the distribution of dry matter from the vegetative organs to the reproductive organs.The ratio of maize root and its crown under RDI has improved basically.The average ratio of root and crown of two-years of T2 and T3 at mature stage was increased by 14.88% and 11.61% compare to CK,respectively.Final average root length was increased by-5.75%~24.34%,and final average root number increased by-2.78%~13.89%.(2)Maize crown wet base moisture content was decreasing along with the growth period,and the root wet base moisture content decreased first and then appeared rebound phenomenon,and showed a growth trend of "V" curve,differences existing among different treatments.About the order of the final crown wet base moisture content from large to small is T2> T1 > T3> CK> T4 >T5.The root wet base moisture content is T5 > T2 > T3> T1 > T4 > CK.The wet base moisture content of the leaves,stems and ears of the single plant decreased along with the growth period,the wet base moisture content of the leaves,stems and spikes all reduced by water deficit.After rehydration,the ear wet base moisture content of T2 to the grain filling stage was improved than CK from seeding to filling stage.(3)Leaf stomatal opening decreased obviously in the water deficit period,and inhibit crop transpiration intensity,but the decrease of photosynthetic rate is not significant.After rehydration,the accumulation and compensation of photosynthetic products was significant,and it was contribution to the increase of yield in the late growth period.Rehydration had a significant compensation effect on the treatment of maize injury flow by regulating loss.The average plant wound flow of two-years of T2 and T3 increased by 12.10% and 11.63% compare to CK,respectively.(4)Appropriate water deficit at appropriate stage is contribution to the increase of ear length,ear diameter,grain number per ear and 100-seed weight,and the increase of bare top length.Compare to CK,the T2 and T3 maize ear length increased 3.23% and 14.21% respectively,ear diameter increased 4.61% and 1.36% respectively,grain number per ear increased 3.97% and1.23% respectively,100-grain weight increased 0.63% and-0.48% respectively,and bare top length decreased 56.08% and 55.16%.Therefore,RDI can improve crop water use efficiency and reduce crop water consumption with not reduce the yield or even increase the yield.Compare to CK,the average crop water consumption of two-years of T2 and T3 decreased by 15.97% and15.38% respectively,which yield increased by 4.94% and 1.59% respectively,and its water use efficiency increased by 25.35% and 20.17% respectively.(5)Using a two-level fuzzy comprehensive evaluation model to evaluate the indexes of maize growing dynamics(plant height,stem diameter,leaf area,leaf matter weight,stem matter weight,ear matter weight and root matter weight),plant moisture dynamics(leaf wet base moisture content,stem wet base moisture content,ear wet base moisture content,root wet base moisture content),physiological dynamics(photosynthetic rate,transpiration rate,stomatal conductance),and water-saving and yield-increasing effects(crop water consumption,yield and water use efficiency).The evalution results show that the T2 was the best treatment of RDI,followed by T3.According to the order of optimal,superior,good,better,general and poor,the evaluation results of all treatments are in sequence of T2,T3,T1,CK,T4 and T5.This conclusion was consistent with the results of two years experiment. |
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