Study On The Law Of Water Requirement And Irrigation Program Of Southern Greenhouse Crops In Our Country

The greenhouse is a kind of efficient and saving energy cultivating facilities for vegetables which are suitable for the natural conditions of our country. However, there are no mature and credible method regarding calculating of greenhouse crops water requirement and irrigation program both at home and abroad. The error of general methods is comparatively large for it base on the rough estimation of open computational method, and therefore can not meet the requirements of the exactness and accurateness of irrigation and water-saving. With the situation of rapid increasing of installed agriculture area in our contury in the recent years, carrying out the research on the law of vegetable water requirement under greenhouse is of great practical value and scientific importance, because it can not only provide datas for the development of installed agriculture and management of irrigation water, but provide guidance for the implement of irrigation water-saving mode of greenhouse crops and the formulation of water-saving irrigation program. The experiment of "Study on the law of water requirement and irrigation program of greenhouse crops" sponsored by the National Natural Science Foundation project is carried out in the Water-saving Irrigation Experiment Station of Hubei Province Water Resources Department during 2005 to 2007. Through the field testing method, the continuous observation and systematic study of the major affect factors of the law of water requirement and water demand of sourthen greenhouse are carried out, the relevance of climate inside and outside of the greenhouse is analyzed, the model of prediction of the climate inside of the greenhouse is established, the applicability of different measurements of surface evaporation capacity in the estimation of the greenhouse crops water requirement is discussed, the model of the law of crops water requirement base on the parameters of the internal greenhouse meteorological element is established, the computational model of greenhouse crops water requirement is improved base on the parameters of the external nautral meteorological element, and the irrigation program of greenhouse crops is studied. Regional practical results are acquired base on the experimental study, laying the foundation for the further applied research.All aspects of research results of the law of greenhouse crops water requirement, the computational model of water requirement and the irrigation methods both at home and abroad are summarized in the thesis. Throught out the study of the two years experimental data of year 2005 to 2006 and year 2006 to 2007, the main research results obtained are as follows:Combined with the actual situation of test site and the base characteristics of greenhouse crops, the field trials program of greenhouse crops water requirement is designed. After summing up the work of the 2005-2006 trial, by laying underground pipe in the greenhouse, installation of automatic drainage, set test pits and other measures to improve the field test program. Greenhouse climate parameters, natural climate parameters and the parameters of the field trials have been systematic observation. Through these works, the field test methods have been exploring on the crop water requirement.By analyzing the greenhouse climate parameters and natural climate parameters, the results show that they follow the same trend and their associated high. Closed characteristics of greenhouse, so the greenhouse climate parameters are different from natural parameters, such as high temperature, high humidity and wind speed. It has the characteristics of mall micro-climate. Accordingly, take the outside meteorological factors as the input vector and take the inside meteorological factors as the output vector to build the BP neural network model, the predicted results of the model is comparatively ideal. The model can not only solve the greenhouse problem the lack of climate data but also predict the greenhouse climate.It can play a guiding role on controlling the greenhouse environment.Analyzing the correlativity between the physiological parameters and environmental parameters measured by the crops growth monitor, namely, through exploring the response of the crops'major organs to VPD, TIR and SM,crops water status is determined in order to find the possible constraints. The results show that the degree of coerce crops water can be reasonable regulated through improving the adjustable environmental factors.Soil moisture data measured by TDR were analyzed according to field water balance principle. The evapo-traspiration of greenhouse crops during the period of duration is calculated and the greenhouse soil moisture change and water requirement is studied.By comparing the surface evaporation data, that meased by E601 method and mass method,with the greenhouse crop water demand data, analysis of correlation between them. The results show that E601 method is not suitable for greenhouse, but quality method does not apply to all greenhouse crops.The relevance of the crops water requirement and the greenhouse temperature system is discussed and temperature model is built.The model has high precision and ts stable,so it can be general.The radiation method and Penman-Monteith model is improved base on the outside climatic factors and the concept of greenhouse crops coefficient is presented, and its conclusion has a wide applicability.The definition of irrigation program of greenhouse crops is derived from the irrigation program of field crops. Based on the growth characteristics of greenhouse crops, the growing period of greenhouse crops is devided and the concept of crops growing season is proposed.The irrigation program of greenhouse is discussed and the test plot's irrigation program of eggplant in greenhouse is formulated. Using the characteristics of surface evaporation that meased by mass method, summed up the trend model.Crop water demand and water evaporation are established quantitative relationship,achieved with water evaporation accumulation of information to predict crop irrigation.The method of quality irrigation which is applied in the production management is concluded. The method is simple and easy to use, having a good practicability.