| In this study, the methods including analysis of field biology, ecology survey, cultivation observation and physiological analysis were used, Sichuan loquat cultivars geographic area (27°-34°N,102°-104°E) including subtropical damp and heat ecotype, southern subtropical semi-dry and hot eco-zone, and southern temperate sub-warm and dry ecotype were investigated. We explored comprehensively the biological characteristics, ecological suitability and the techniques of cultivation and flowering time regulation based on the dominating loquat cultivar Dawuxing. And focused on the ecological effects of loquat growth and formation, yield and quality in different eco-zones, flowering control technology, plastic shed cultivation, and fruit frost damage. The main results were as follows:1. In mid-subtropical damp and heat ecotype, the buds were mainly from the summer shoots with flowering stage concentrated from September to December. The fruit quality was good and maturity of May. Freezing injury and diseases including Sunburn, cracking, shrinking fruit, leaf spot and flower rot were often occurred. In subtropical semi-dry and hot eco-zone, flower could be formed from spring and summer shoots with florescence from June to November. There was no frost damage and fruit stagnant period, the maturity was early during October and next April, but the fruit from the first florescence was small and poor quality. Loquat canker, bud blight and fruit quercus disease should to be prevented. In the valley of southern temperate warm and dry ecotype, the ecological response of loquat was similar to those in less sunshine and humid subtropical eco-zones. The phenophase was late 20-30d with super fruit quality, and panicles were mainly from summer shoots. The amount yield of annual loquat showed a gradual reduction and fruiting branches were mainly from spring shoots with altitude increasing, and the panicles were difficult to be formation and loquat yield could fall sharply by serious chilling injury in some year at altitude more than 1920m with cold temperature of summer and autumn.2. Flowering time regulation was a key factor for achieving economic yield in subtropical semi-dry and hot ecotype. By rational combination of loquat varieties with diverse flowering time and cutting back pruning techniques during middle of February to early April, blooming phase could be regulated and reduced the numbers of early and late flowers. The mature period could be regulated from December to next March with high proportion of good fruit. The techniques of cutting back pruning and the controlling of fertilizer and water were the most effective ways to regulate flowering phase and could most achieve the marketed supply anniversary of loquat in Sichuan.3. In the mid-subtropical damp and heat ecotype, the temperature was higher in plastic shed than that in the open field. The soil temperature was increasing when the air temperature high, but this change scope was less. The plastic film covered on shed ground could increase the soil temperature, and there was not much difference between different films. The relative humidity inside greenhouse was higher than that in open field at the same time. The air temperature higher, the relative humidity was lower, and the changes of relative humidity in open field were greater than that in greenhouse. The soil moisture was highest in film compared to that no film or that exposed in air, and relatively stable at different times. Among the different color films, Silver reflected light strongest with the best light environment. In plastic shed, the late florescence was advanced 5-6 days, mature period was advanced 10 days and spring and summer shoots could be advanced one week and 3-4 days, respectively. Fruit shape was long oval in greenhouse and nearly round in exposed air, the soluble solids and soluble sugar content were decrease for loquat under condition of plastic shed exclude the big volume. However, the two indexes were better in film covering environments compared to that in no film, and not much difference was observed in fruit volume. The incidence of sun scald and fruit shrink disease was increase, rust disease and fruit cracking rate was reduced in the cultivation circumstance of plastic shed.4. Freezing injury often occurred in the mid-subtropical damp and heat ecotype and southern temperate warm and dry ecotype and had become an important limiting factor for loquat economic plantation. The freezing damage in the flatland regions was more serious than that of in slopes by the method of tissue browning, juvenile fruit was tend to injury by freezing than that flowers from different development, and the resistance to cold was best in just flowering and bud tissues. The measures including plastic shed, fruit bagging, shading net and film mulching of tree crown were useful for loquat resistance to freezing damage, and the effect of plastic shed was best. Frost damage most occurred when the minimum temperature less than-0.6℃lasting for above 3 hours with humidity more than 90%. The damage with different degree could be occurred in the flowers and young fruits, and tend to serious with strong frost low temperature and high humidity. Physicochemical index indicated that significant linear correlations were observed between freezing index and SOD activity, and relative electric conductivity in slopes terrain at highly significant level. There was a significant negative correlation between the content of MDA and freezing index at 5% significant level for samples in the flatland, but was not significant compared with that in slope terrain. In addition, the content of proline would increase with temperature decreasing.5. The optimum concentrations of spraying SA and CaCl2 were 90mg/L and 2g/L respectively based on the indexes of frost and physiology. The same physical index was various in different organizes, and there was no significant variance of chlorophyll contents in treatments of diverse chemicals. The biological responses were diverse for different tissues of loquat Dawuxing to frost and exogenous chemicals. The proline content was highest in flowers when spraying the chemical of SA. In the three soaking treatments, the best effect was SA, the better was CaCl2, and the last was CaCl2+K2SO4 based on the analysis of MDA. There was clearly spraying time for some physical index based on same chemicals, but no best spraying phase for exogenous substance in different frosts. The soaking treatment of young fruits in GA (200mg·kg-1)+CPPU (20mg·kg-1) would reduce the effect of freezing damage. The index of fruit shape was increased and numbers of seeds was decreased by spraying GA and CPPU, which could be as the emergency measures when frost occurred.These results obtained from comprehensive investigation would provide valuable information for techniques of cultivation in distinctive ecotypes, and facilitated the economic plantation for loquats in the diverse eco-zones of the world. The behavior of flower formation, condition and relationship with ecological environments was explored and the reason of fruiting several times a year in was made clearly. The techniques of blooming phase regulation could break through the limitation of traditional method and solved the problem of flowers shortage in autumn and beyond enough in summer. The effects of simple shed cultivation on loquat growth, flowering, yield and quality were identified and could be used as reference for protected cultivation. The results of frost study provided climatic insights to freezing damage and physiological indexes of cold hardiness in loquat, which would be useful in preventive and remedial countermeasures of frost injury in loquat plantation.
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