Correlation and path analysis between mineral elements and quality parameters in non-astringent persimmon

Abstract: 【Objective】In this study,correlation and path analysis were conducted in persimmon fruit col-lected from orchards in Mei County,to investigate the relationship between contents of mineral elements(N,P,K,Ca,Mg,Fe,Mn,Cu,and Zu) and fruit quality indexes(fruit weight,fruit shape index,hard-ness,soluble solids,titratable acids and vitamin C). Via screening the major mineral elements that affectfruit quality and analyzing specific elements that affect specific fruit quality indexes,this study was toprovide a theoretical basis for rational fertilization to improve fruit quality in persimmon orchard.【Meth-ods】Fruit were washed with 0.1% detergent solution for 30 s,then rinsed with tap water,and then withdeionized water for 3 times. Part of sampled fruit from each orchard was placed in nylon mesh bags and al-lowed to be surface dried in a ventilated place. The sample was then placed in an oven set at 105 ℃ for 10 min and then at 80 ℃ until fully dried. The dried sample was ground with an agate mortar,and the pow-der screened through a 100 mesh nylon sieve was stored in a plastic bottle for later analyses. Total nitrogen(TN)was determined by the method of Kjeldahl. P,K,Ca,Mg,Fe,Mn,Zn,and Cu were determined by the method of plasma emission spectrometry. The weight and shape index were measured using a scalewith a precision of 0.01 g. and a caliper,respectively. Soluble solids and hardness of fruit were deter-mined with a digital sugars meter TD-45 and explicit durometer. Titratable acid content and Vitamin Cwere determined by the method of Na OH neutralization titration and 2.6-dichlorophenol indophenol,re-spectively. The correlation and path coefficient of mineral elements and fruit quality indexes were ana-lyzed by SAS software.【Results】Quality indexes differed among fruit sampled from different orchards.The titration acid content had the greatest variation(variation coefficient 35.8%) and flesh hardness hadthe lowest(variation coefficient 11.1%). The average of each quality index reached the requirements ofcommodity fruit. The variations of fruit mineral element contents in different orchards were large,with co-efficient of variations ranging from 19.3% to 71.2%. Among the macro elements,K was the highest,andP,Ca,N and Mg were the lowest. As for the trace elements,Fe was the highest and Cu the lowest. Thecontents of mineral elements were interrelated with each other. N was significantly positively correlatedwith K,Ca,Cu and N,and negatively correlated with Zn;K was significantly correlated with Ca andMg;Ca was significantly correlated with Mg. The fruit hardness was significantly positively correlatedwith Ca and Mn;soluble solids were positively correlated with K;the titration acid was significantlypositively correlated with N and negatively with P;and the content of vitamin C was positively correlat-ed with K. In addition,fruit weight,fruit shape index and mineral elements had no significant correla-tion. Path analysis further demonstrated that N had the most significant effect on titrable acidity(pathcoefficient 0.694),and the greatest direct negative effect on fruit weight,firmness,and soluble sol-ids(-0.362,-0.548 and-0.515). The effect of P on hardness reached a significant level with a path coef-ficient of 0.45. K had the most significant effect on soluble solids(0.918) and the greatest direct negativeeffect on titrable acidity and soluble tannin(-0.723 and-0.715). The direct effects of Mg on fruit shape in-dex and soluble tannin were relatively great with path coefficients of 0.49 and 0.794 respectively. Zn andMn had a large positive direct effect on vitamin C content. Different mineral elements had different effectson fruit quality. Among the mineral elements,the direct contribution to fruit weight was P > N > Cu >Mg > Mn > Zn > K > Ca;to fruit shape index was Mg > Fe > Cu > Zn > Mn > N > Ca;to fruit hardnesswas N > P > Ca > Mn > Mg > Zn > Fe;to soluble solids was K > N > P > Ca > Fe;to titration acid wasK > N > Cu > Mg > P;and to vitamin C was Zn > Mn > Mg > P > N.【Conclusion】Controlling or reducingN application,with adding P,K,Zn and Mn appropriately improve fruit quality. Rationalizing the propor-tion of various nutrient elements guarantees a high quality persimmon production.