Yield,Sensory Profile,and Physico-chemical Quality Attributes Of Prunus Domestica × Armeniaca ‘weidi' Fruits As Affected By Crop Load

Prunus domestica × armeniaca are new cultivars screened out from the multiple hybridization between apricot(P.salicina)and plum(P.armeniaca).The fruit of 'Weidi' has a unique flavor that is different from a standard plum or apricot and a better balance between sugar and acid.In addition,it is rich in minerals and other active ingredients,such as polyphenols,flavonoids,and carotenoids,thus it is highly favored by consumers,and its cultivation area in China is rapidly growing.This research attempted to investigate(i)the impact of crop load on the yield and ordinary quality characteristics of Prunus domestica × armeniaca including total soluble solids(TSS),total acidity(TA),weight,size,pH,and color;and(ii)the effect of crop load on the sensory profile that was constituted by soluble sugars,organic acids,FAA,and volatile compounds;moreover,(iii)the impact of crop load on antioxidant capacity and phytochemicals such as polyphenols,flavonoids,carotenoids and anthocyanins.The results were as follows:1.Total yield and yield of each category fruitsThe total yield per tree decreased with the decrease of the crop load,in which small-sized and medium-sized fruits and the yield of non-commercial fruits had similar changes with total yield.However,the yield of large-sized fruit increased first and then decreased,and the maximum yield was in the moderate crop load(T2 treatment).Yield of large-sized fruits had a significant relationship with crop load,which was expressed as a quadratic relationship in which the maximum yield occurred when the crop load level was 1.53 fruits cm-2 of TCSA.Fruit size distribution shifted towards larger fruit sizes with decreasing crop load level.The percent of commercial fruits and large-sized fruits showed a different trend.In terms of the commercial fruit percent,it increased greatly in heavy(T1 treatment),moderate,and light crop(T3 treatment)load level compared with that of CK,but there was no significant difference among the three levels.The large-sized fruit percent of heavy,moderate,and light crop load level was 40.42%,73.15%,and 85.53%,and respectively increased by 18.94%,51.67%,and 64.05% as compared to CK.2.Attributes of fruit quality and fresh color parametersThe size of fruits was reduced with rising crop load,which had a significant effect on Prunus domestica × armeniaca in terms of fruit weight,as well as mean values for the diameter and length of fruits,but fruit shape was unaffected by crop load in this study.As far as the flesh firmness and moisture,they both decreased with the decrease of the load TSS and TA were also influenced by the crop load as both the TSS and TA of the fruits from each treatment were larger than the control samples.However,only the fruits at moderate load had greater value of TSS/TA than CK.For the fresh color,there was no significant difference of the examined attributes of color in this experiment among the various treatments.3.Sensory profile for the pulpFor the sensory profile,reduction of crop load improved concentration of four types of sugars(sucrose,glucose,fructose,and sorbitol)and malic acid,and the maximum of total sugar and total acid increase were 40.94% and 27.58% respectively compared with the CK.Reduction of crop load also reduced some free amino acids,such as aspartic acid,asparagine,histidine,lysine,and hydroxyproline.Sweet and sour sensory quality was better in fruits from moderate and light load trees by sensory analysis.Total volatile content in fruit decreased with increase in the load(except heavy load);however,total odor activity value of the characteristic components of the fruits remained unchanged.Fruits of reduced crop loads had higher content of linalool(floral)and lower content of ethyl acetate(fruity).4.Phenolic compounds and the antioxidant content of the pulpThe fruit pulp of Prunus domestica × armeniaca contained high amounts of antioxidants,including phenolics,flavonoids,anthocyanins,and carotenoids.Among these groups,the concentration of total phenols in light load level was significantly higher than that of the other three load levels;meanwhile,lower concentration of anthocyanin was presented at light crop load level.Also,the concentration of total flavonoids and carotenoid remained the same in lower crop loads.Meanwhile,no differences of the antioxidant capacities,determined with DPPH,ABTS,or FRAP assays,were observed at different crop load.