Preliminary Study Of Orchard Monitoring And Planning Model

Citrus is a subtropical fruit tree, which is mainly distributed between20°-33°north latitude, covering19provinces (municipalities and autonomous regions). Recent studies have shown that the global warming trend of these regions will aggravate further, the inequality of distribution of rainfall will be more serious, the frequency of extreme weather events will increase; The place of production in china are mostly mountains and hills, undulating terrain, the magnitude of microclimate change is large, orchard planning and management is not easy. Therefore, this study has four aspects as follows:1、The impact of climate change on citrus:This part mainly studied two factors-temperature and precipitation in all the meteorological factors, we analyze the temperature and precipitation trends in different regions of China in recent decades, and their impact on fruit quality, phenophase and yield of citrus. In the study of the trends of climate change, we found the annual average temperature in most areas of our country is rising, but the extreme low temperature in January fluctuating irregularly, the changes of annual rainfall in the South is very small, it has increased and decreased; In analysis of the impact on fruit quality, temperature and precipitation have very significant correlations with soluble solids content of fruit, and they are all positively correlated; In the research of citrus’phenophase, we found that the annual rainfall and the germination stage,the average annual temperature and the final bloom stage、frondesce stage of summer branches and autumn branches had significantly relations.The annual precipitation and early blooming stage、full blooming stage correlated significantly,in addition to annual rainfall and germination stage, others were negatively related,while there are a rising trend in mean annual temperature and annual rainfall,if this situation continued,it wound delay the harvest day which may increase the danger of freezing to fruit.In analysis of production,the monthly average temperature of September October、 November and the precipitation of December with the production were significantly related.2、A high and stable yield of citrus is closely related to the growth and development of branches, which give the morphological structure of canopy. Monitoring the dynamic development of branches can help to understand behavior of plant at young stage. By analyzing the position of and the number of internodes in branches of Newhall navel orange, we found that the distribution of the spring, summer, fall branches were statistically the same:they all present a normal distribution, and branching probabilities from the highest node on mother axis were highest, being40%,60%and50%respectively. The average number of2year-old branches, were significantly different from3year-old and7year-old trees, while latter two were statistically similar, which may hint that the growth of Newhall follows a certain species specific pattern. We established a structure visualization model for a two year-old Newhall based on Xplo system developed by France.3、Electrical conductivity is an important physiological and biochemical index which reflects the situation of plant biomembrane system and also reflects the nutrient condition of trees. The nutrition of the tree before winter is an important factor which resists extreme low temperature for surviving through the winter, the exudation or degradation of cell sap is an index of freezing degree when freezing injury happened. Our research is scanning the different leaves in different freezing levels with a spectrometer, using a stepwise regression method to analyze the relation between spectral reflectivity and leaf conductivity, and then constructing the leaf conductivity and spectral reflection model. The results show that there is a close relationship between citrus leaf electrical conductivity and spectral reflectance, the errors of predicted one and measured one are both less than10%, which proves these two models have good predicted results. The results can provide a reference for remote sensing to monitor the growth status and cold injury situation of orchards.4、In search for a optimal density of orchard:Suppose the citrus’canopy is a uniform sphere, according to the local latitude cp, solar declination8and hour angle ω and the solar elevation angle hs, we establish a canopy shading model using the genetic algorithm, by simulating natural evolutionary process, to obtain the optimal solution of the cumulative unshaded parts per unit area within a day. The appropriate plant spacing is in the range of2-2.88times’radius of canopy.If ignored the orchard road, only according to the maximized received light amount of orchard to plan, for the canopy diameter is about3meters in citrus orchard, the planting density is approximately63trees per acre.