| Pingyuan,Meizhou in Guangdong Province,as the hometown of navel oranges in Guangdong,currently have grow more than 30,000 mu of umbilicus,with a total production of more than 10,000 tons.Due to the lack of scientific production management,farmers used extensive plant management methods,which caused excessive consumption of local water resources.Pingyuan is a city which is uneven rainfall,there is no scientific management of water resources and seasonal droughts occur,which will seriously affect the high yield of local navel oranges.Therefore,it is of great significance to discuss how to achieve high quality and high yield of navel orange under the condition of insufficient irrigation,and to deal with the imbalance of water resources and the contradiction of crop production.In order to formulate a scientific and rational irrigation system,explore the effects of different water treatments on the growth and quality of Pingyuan navel orange and analyzing the law of water consumption,an experiment was carried out at Pingyuan-Meizhou,Guangdong in the growing season from 2015 to 2016.The experimental design was Complete Randomized Block Design(CRBD)with sufficient water supply(75%FC)during the whole growing stages,mild,moderate and severe water deficits(55%FC,45%FC and 35%FC)at blossom and fruit stage,fruit growth stage,fruit coloring stag and fruit maturity stage,with three replications.Combined with the data of 2014,exploring the changing rules of fruit diameter,fruit weight,vitamin C content and sugar content of navel orange under different water conditions,the effects of different water deficit treatments on the growth and quality of navel orange fruit were analyzed.Base on the theory of water balance equation,the water consumption under different water treatment were calculated,the water use efficiency also calculated combining with the yield,and finally formulated an irrigation system for navel orange under regulated deficit irrigation according to the local meteorological conditions.The main conclusions of this study are as follows:(1)Through the result of the growth,yield and quality of navel orange under different depletion treatments indicated that 45%FC at blossom and fruit stage can improve the weight and growth compared with CK;the fruit growth stage is the most sensitive period on water consumption,under 55%FC can form a good compensation on growth,weight and quality.Dehydration treatment at fruit coloring stag and fruit maturity stage can improve the quality to a certain degree after inhibiting the growth and yield.Combining with the conclusions of the study,we believe that under 55%~70%FC at fruit growth stage,45%FC at blossom and fruit stage,fruit coloring stage and fruit maturity stage can improve the quality of navel oranges and harvest better orange quality.(2)The water consumption of navel oranges is also different at different growth periods.The water consumption and daily consumption at fruit growth stage are the largest than other stages.Therefore,it is not suitable for excessive loss of water treatment during fruit growth stage,which is the water sensitive period and the peak of water consumption.We also found that after the navel orange is treated with water deficit,water consumption in the next growth period will be compensated and rebounded to a certain degree,however,severe shortage of water is limited,which can lead to negative impact.The experiment also showed that with the reduction of water consumption,the yield and water use efficiency have not always been decreasing.The fruit growth stage is the moisture-sensitive period of navel orange,at which 55%FC can steady achievement of water consumption replenishment and promote fruit growth,increase water use efficiency,increase fruit yield.At the same time,it is beneficial to improve the effective utilization of water resources by 45%FC at blossom and fruit stage,fruit coloring stage.(3)The correlation coefficient is 0.5929 and 0.6026,after linear and nonlinear regression analysis of moisture production function in the whole growth stage of navel orange,which show that there is a positive correlation between water consumption and production within a certain range,but the accuracy is not high.(4)Calculating the sensitivity coefficient by using the addition model like Blank model and Singh model,multiplicative model like Jensen model and Minhas model,and after the analysis,we found that Jensen model can reasonably reflect the relationship between water consumption and yield of navel orange,and the sensitivity coefficient are as follow:0.1882 at blossom and fruit stage,0.3392 at fruit growth stage,0.0941 at fruit coloring stage and 0.0833 at fruit maturity stage.It showed that fruit growth stage is the moisture sensitive period of navel orange,so we should ensure the water supply;fruit maturity stage is the least sensitivity,at which the correlation between water consumption and yield is not high,after water deficit treatment can reduce water consumption.(5)The Kc value was different at different stages,and the largest one is 1.32 at fruit growth stage,which is the rapid development stage with high temperature,long growth period,and high water consumption.The Kc value of fruit maturity stage is the least,the main reason is that the growth and development slows down,temperature drops slightly and the water consumption decreases.The result showed that the irrigation should according to the amount of moisture sensitivity,in order to avoid unsuitable irrigation make an bad effect on growth and yield of navel orange,or causes the waste of water.(6)Established an irrigation system for navel orange under regulated deficit irrigation.The experiment determines the upper and lower limits of soil moisture,combined the designed moisten layer of soil and soil properties,the irrigation water quota are 15.54mm?23.31mm?7.77 mm and 7.77 mm at blossom and fruit stage,fruit growth stage,fruit coloring stag and fruit maturity stage,the water cycle are 12d?7d?4d and 3d.After the balance of water requirement and natural rainfall,the optimal irrigation procedure are sa follow: in wet year,it needs to be irrigated twice in July,when is at the period of fruit growth stage,and the water quota are 15.54mm;irrigation is required once at the fruit coloring stage in October once,and once at the fruit maturity stage in October and once at the fruit maturity stage in November with the water quota of 15.54mm;in normal year,it needs to be irrigated once at the fruit coloring stage in October once,once at the fruit maturity stage in October,and twice at the fruit maturity stage in November with the water quota of 15.54mm;in dry year,it needs to be irrigated twice at the period of fruit growth stage in June,with the water quota of 23.31 mm,twice at the fruit maturity stage in November with the water quota of 15.54mm;in low flow year,it needs to be irrigated once at blossom and fruit stage in April with the water quota of 15.54 mm.In our daily farming,it is necessary to ensure seasonal irrigation supplements according to the deficient water situation,and water reserve preparations can be made properly. |
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