Study On Water Resources Efficent Utilization And Pitaya Physiological Ecology In Typical Peak Cluster Depression

Drought and water shortage is an important factor hindering economic development in karst areas.This paper mainly introduces the distribution of carbonate rocks and the development status,potential and main development technologies of karst water resources abroad,and analyzes several successful cases of water resources development and utilization in typical karst areas such as Tennessee karst basin in the United States,Apulia＆ Basilicata karst basin in Italy,Europe,and Neretwa-Trebisnjica River Basin in Bosnia ＆Herzegovina,Europe.Several successful models of karst water resources development,such as “the comprehensive development and management model of karst water resources in small and medium-sized basins of Tennessee in the United States”,“the coordinated development model of karst water resources in large or cross basin scale（regional）in Europe”,“ the model of collection,storage and utilization of rainwater ＆ surface karst water in Albertobello karst mountain area”,“the cascade storage,comprehensive development and utilization of karst water resources in neretwa trebinet basin” are summarized.The development trend of water resources development and utilization in karst area is predicted.It is expected to provide reference for the development and utilization of water resources in karst areas in China.Aiming at the karst environment of poor groundwater resources,serious surface drought and water shortage in impure carbonate karst peak cluster depression area,a case study was carried in a typical karst peak cluster depression unit in Yexu,Taiping Town,Pingguo city,Guangxi.Based on detailed karst hydrological monitoring and water resources evaluation,some water resource development technologies,such as Rainwater collection,slope surface water interception and storage in closed depression,extracting groundwater from Karst wells or by drilling,and introducing groundwater developed from an adjacent rich karst water area into the demonstration area as supplementary water resources during extreme dry seasons,were invented or adopted.A system for comprehensive regulation and utilization of karst water resources from different sources above was established,which form a typical mode called “Yexu mode of karst water resources development and utilization ".According to this mode,the problem of drought and water shortage in red fruit planting in poor karst mountainous areas of Pingguo has been solved successfully,and it also provides a new model for the development and utilization of water resources in impure carbonate poor karst peak cluster depression in China.In order to solve the problem of insufficient irrigation water resource due to the unreasonable allocation of water and soil,significantly higher of crop irrigation water demand than that in non karst areas,and low irrigation efficiency in peak cluster depression area,a scientific experimental study of high efficiency irrigation was carried out.As a case study,a test area of pitaya planting with 3 comparative test plots were established to test the irrigation effect under different irrigation scheme（different irrigation water volume and irrigation frequency under different topographic,geological and soil conditions）in a pitaya planting test base in a cluster depression in yexu village,Taiping Town,Pingguo City,Guangxi.The irrigation effect is obtained by monitoring and comparing the branch growth length,fruit weight,length and perimeter of pitaya.The result showed that,the growth of Pitaya generally increased first and then decreased with the increase of irrigation water and irrigation frequency.Among them,it is conducive to the growth of Pitaya branches（stems）when irrigating once every 6 days,1.5-2.5l/plant every time.At 1.5l/plant every time,pitaya branches reach the maximum growth,while excessive irrigation is not conducive to the growth of Pitaya branches.However,the demand of water is relatively small during pitaya fruit developing to mature,with a best effect of 0.5-1.0l/plant every time,and once every 6 days or longer.The demand of Pitaya for irrigation water is also affected by terrain,geology and soil conditions,which is the largest under dolomite area,with steep terrain,thin soil layer and rough soil texture.In the irrigation scheme of once every 6 days,the optimal irrigation water volume of Pitaya is1.0l/plant under clastic rock gentle slope condition during the growth period of branch,and 1.5-2.0l/plant respectively for the two dolomite cultivated condition,and 0,0.5L and 2.0L respectively under clastic rock gentle slope,gentle slope of dolomite area and middle slope of dolomite area during the period from development to maturity.Therefore,it is necessary to implement the detailed irrigation water scheme or field water management scheme for pitaya planting by time and space,especially for the peak cluster depression area with serious water shortage,which is the guarantee of scientific water management,cost saving and improving irrigation water efficiency.It has important popularization and application value for promoting the development of Pitaya ecological industry in peak cluster area.By calculating the membership degree of physiological and ecological indicators,the drought resistance of typical economic plants（pitaya）was comprehensively analyzed,and the adaptability of typical plants to the environment was evaluated.The results show that the regulation of water and fertilizer regulation> irrigation interval regulation> irrigation amount regulation.The content of MDA（malondialdehyde）and POD（peroxidase）is closely related to plant resistance,and to some extent,it can be considered that the content in plants is inversely proportional to plant drought resistance.The higher the soluble protein concentration,SOD,CAT,VC,PRO and soluble sugar content,the stronger the adaptability to stress,and on the whole dolomite slope has higher drought resistance than the other two plots,showing high adaptability to stress.