采收成熟度对‘玉露香’梨果实品质和耐贮性的影响

Effects of harvest maturity on fruit quality and storage life of‘Yuluxiang'pears

【目的】研究不同采收成熟度对梨优新品种‘玉露香’采后品质和贮藏效果的影响,以明确其采后生理特性、适宜采收成熟度参数,为生产上优新品种的大面积推广提供技术支撑。【方法】以山西太谷‘玉露香’为材料,分3个采收成熟度进行采收后,测定常温(20℃)和冷藏(0℃)条件下果实可溶性固形物含量、可滴定酸含量、维生素C含量、果皮颜色、叶绿素荧光参数、相对电导率、单果质量、硬度、种子颜色指数等生理指标,并调查了不同贮藏期果实黑心指数、磕碰伤百分率和腐烂率。【结果】常温条件下,随着货架时间的延长,果实硬度、可溶性固形物含量、可滴定酸和维生素C含量逐渐下降,反映果皮颜色的h值不断下降,L值不断升高,叶绿素荧光参数中Fv、Fv/Fm不断下降,而F0、F0/Fm不断升高;随着采收成熟度的增加,可溶性固形物含量、可滴定酸含量、单果质量和种子颜色指数不断增加,果实硬度不断下降,而维生素C含量以采收期Ⅱ最高。h值逐渐下降,L值逐渐升高。冷藏条件下,采收期Ⅲ的h值显著低于采收期Ⅰ和采收期Ⅱ(P<0.05),L值则显著高于采收期Ⅰ和采收期Ⅱ(P<0.05)。冷藏至240 d和240+10 d货架时,采收期Ⅲ的F0、Fm和Fv显著低于采收期Ⅰ和采收期Ⅱ(P<0.05),采收期Ⅰ的相对电导率显著低于采收期Ⅱ和采收期Ⅲ,而采收期Ⅲ果实的黑心指数、磕碰伤百分率和腐烂率显著高于采收期Ⅰ和采收期Ⅱ(P<0.05)。L与Fm、Fv、Fv/Fm呈极显著负相关(P<0.01),与F0/Fm呈极显著正相关(P<0.01);h与Fm、Fv呈极显著正相关(P<0.01),与Fv/Fm呈显著正相关(P<0.05),与F0/Fm呈显著负相关(P<0.05);表征果皮颜色的h值和表征果皮油腻化程度的L值间呈极显著负相关(P<0.01)。【结论】对于梨优新品种‘玉露香’的建议:采收后立即销售或短期冷藏(贮藏期不超过120 d)的果实可在9月上中旬采收,用于长期冷藏的果实(尤其是贮藏期达240 d左右),建议9月上旬采收。

【Objective】The optimal harvest maturity of the the new pear variety‘Yuluxiang＇is not known. This study investigated the postharvest quality and preservation of‘Yuluxiang＇harvested at different maturities and stored at room temperature and cold temperature so as to determine the optimal maturity for harvest and to promote the extension of this outstanding new variety. 【Methods】Shanxi Taigu‘Yuluxiang＇were harvested at three stages of maturity at 130, 141 and 152 days after full bloom on 27 th August, 7thSeptember and 18 thSeptember, respectively. Fruit with uniform size and color and without any mechanical injury or disease and insect pest damage were selected and packed with polyethylene plastic bag（0.02 mm in thickness）. Part of the fruit sample were used for room temperature（20±0.5 ℃） storage and for the determination of physiological indexes. The remaining fruit were stored in cold temperature（0±0.3 ℃, relative humidity 85%-95%）, and soluble solid content, titratable acidity, vitamin C content and other internal quality index, peel color, chlorophyll a prime fluorescence parameters, relative electrical conductivity, single fruit weight and firmness were recorded, and seed color index, brown heart index,wounded percentage and decay rate were determined at different periods.【Results】Under room temperature（20 ℃）, fruit firmness, the content of soluble solids, titratable acid and vitamin C gradually declined,skin h and L values rose, Fv and Fv/Fmdecreased, and F0, F0/Fmincreased. At day 30, Fvand Fv/Fmin fruit harvested at different times fell sharply, and the two indexes were significantly lower in fruit harvested at stage Ⅲ than those harvested at stages Ⅰ and Ⅱ（P﹤0.05）. F0/Fmin fruit harvested at stage Ⅲ was significantly higher than those harvested at stage Ⅰ and Ⅱ（P〈0.05）. Soluble solids, titratable acid, single fruit weight and seed color index, L value of skin increased while fruit firmness and H value decreased as fruit became more mature, and vitamin C content was the highest in fruit harvested at stage II. At day 15,h value in fruit harvested at stage Ⅲ was significantly lower while the L value was significantly higher than in those harvested at stage Ⅰ and Ⅱ（P〈0.05）. In cold storage（0 ℃）, h value in fruit harvested at stage III was significantly lower while L values was significantly higher than in those harvested at stage Ⅰand Ⅱ（P〈0.05）. At 240 d of cold storage, F0, Fmand Fvin fruit harvested at stage Ⅲ were significantly lower than in those harvested at stage Ⅰ and Ⅱ（P〈0.05）. The relative electrical conductivity increased and was highest in fruit harvested at stage III and significantly lower in fruit harvested at stage I than in those harvested at stage Ⅱand Ⅲ. At 120 d of cold storage, the brown heart index was low, and no significant difference among fruits harvested at different stages. At day 10 of shelflife, the brown heart index increased. It was significantly lower in fruit harvested at stage I than those harvested at stage Ⅱ and Ⅲ（P〈0.05）. By day 240, the brown heart index had increased significantly, and it was significantly higher in fruit harvested at stage III than those harvested at stage Ⅰand Ⅱ. The percentage of wounded fruit harvested at stage Ⅲ was significantly higher than those harvested at stageⅠ and Ⅱ, and it was higher at day240 than at day 120, but did not change significantly during shelf life. At 120 and 240 d of cold storage,the decay rate in fruit harvested at stage Ⅲ was highest. There were significantly negative correlations between L and Fm, Fv, and Fv/Fm（P〈0.01） and a significant positive correlation between L and F0/ Fm（P〈0.01）. H and Fm, h and Fv, and h and Fv/Fm were significantly and positively correlated（P〈0.05）, while and h with F0/Fmhad a significant negative correlation（P〈0.05）. The h value of fruit skin that reflects the abundance of skin wax was significantly and negatively correlated to L values（P〈0.01）.【Conclusion】It is recommended that this new pear variety can be harvested in mid September if they are to be marketed immediately after harvest or stored in cold for no more than 120 d. However, for long-term cold storage（up to 240 d）, it is better to harvest the fruit in early September.