Studies On Oleocellosis Control And The Effect Of Harvest Method On Fruit Postharvest Performances In Navel Orange

Navel oranges are the main economic crops grown in Fengjie,Chongqing and Zigui,Hubei in the Three Gorges Reservoir area.They play a very important role in increasing the income of local fruit farmers and realizing rural revitalization.Scientific harvesting and proper commercialization are important measures to ensure the quality and efficiency of the citrus industry,and they are also a key link that affects the citrus industry chain in country.Fruit quality and production costs are directly related to the market competitiveness and industrial benefits of navel oranges.The main navel orange variety’Fengjie 72-1’ in Fengjie County is prone to oleocellosis.The appearance and quality of the fruit is not good due to oleocellosis,which reduces consumers’ desire to buy and market competitiveness.On the other hand,the traditional harvesting method of ’one fruit and two cuts’ is inefficient,and the labor cost is high.Workers picking with leaves extensively cause damage to the fruit surface and make it difficult to store and keep fresh.At present,the "bare-hand harvesting" method implemented in Zigui production area has high picking efficiency and reduces the risk of post-harvest puncture,but there is no scientific basis for whether it affects the post-harvest quality of the fruit.In response to the actual needs of the above-mentioned production areas,this experiment carried out the feasibility of the control of ’Fengjie 72-1’ navel orange oleocellosis,as well as the feasibility of "bare-hand harvesting" of navel oranges in the reservoir area instead of the traditional ’one fruit and two cuts’ harvesting method.The research has achieved the following main results:1.Control of ‘Fengjie 72-1’ navel orange oleocellosis(1)The control effect of preharvest treatment: fruit wax>A(self-developed formula)>brassinolide>CK>melatonin>ethephon.A treatment and fruit wax treatment can induce the accumulation of waxes(alkanes and primary alcohols),cutin(hydroxy fatty acids)and lignin content,improve the mechanical strength of cells,reduce water loss,and had obvious effects on the control of ’Fengjie 72-1’ navel orange oleocellosis.Among them,fruit wax can significantly reduce the incidence of oleocellosis,the degree of oleocellosis and rotting rate of fruits,improve the storage quality of fruits after harvest,and delay the senescence of fruits.The storage and preservation effect is the best among the five pre-harvest treatments.(2)Cytological studies have found that the parenchyma cells of fruit peels in high-altitude areas and low-altitude areas are looser,with cracks and gaps,and oleocellosis are more likely to occur.The oil cells of the diseased peel are raised compared to the normal parts,and the waxy surface is thin and lamellae.There is no obvious difference between the 1-2 layers of the epidermal cells of the peel.Starting from the third layer,the parenchyma cells in the diseased part have plasmolysis,cell accumulation and shrinkage,disordered inclusions,thinning of the cell wall and folding and distortion.2.The effect of "bare-hand harvesting" on the commercial performance of navel orange fruitsIn this experiment,by comparing the harvest rate and a series of physiological and biochemical qualities of fruits picked by two different harvesting methods,"bare-hand harvesting" and ’one fruit and two cuts’,it was found that the harvest rate of the "bare-hand harvesting" method was Two times the traditional ’one fruit and two cuts’,And the resulting fruit without pedicle and fruit with pedicle have no significant difference in the residual amount of fungicide such as imazalil and a series of physiological and biochemical qualities of the fruit during storage.It shows that "bare-hand harvesting" has no significant effect on fruit quality than ’one fruit and two cuts’,which provides a new technical reference for the harvesting methods of navel oranges.In summary,this research has gained a new understanding of the cause of ’Fengjie72-1’ navel orange oleocellosis,and further studied the pathogenic mechanism of oleocellosis;the study found that "bare-hand harvesting" without fruit pedicles method can reduce labor costs and avoid fruit injury.The research results provide a theoretical basis for the control of citrus oleocellosis and the harvesting methods of navel oranges.