Sample size for postharvest quality traits of ‘Palmer’ mangoes

Abstract The objective of this study was to determine the most efficient sample size required to estimate the mean of postharvest quality traits of ‘Palmer’ mangoes harvested in two growing seasons. A total of 50 mangoes were harvested at maturity stage 2, in winter (June 2020) and spring (October 2020), and evaluated for weight, length, ventral and transverse diameter, skin and pulp L*, C* and hº, dry matter, firmness, soluble solids (SS), titratable acidity (TA) and the SS/TA ratio. According to the results, the coefficient of variation (CV) of fruit quality traits ranged from 2.1% to 18.1%. The highest CV in both harvests was observed for the SS/TA ratio, while the lowest was reported for pulp hº. In order to estimate the mean of physicochemical traits of ‘Palmer’ mangoes, 12 fruits are needed in the winter and 14 in the spring, considering an estimation error of 10% and a confidence interval of 95%. TA and the SS/TA ratio required the highest sample size, while L* and hº required the lowest sample size. In conclusion, the variability was different among physicochemical traits and seasons, implying that different sample sizes are required to estimate the mean of different quality traits in different growing seasons.

摘要：本研究旨在确定估算两个生长季采收的‘Palmer’芒果采后品质性状均值所需的最优样本量。本研究于2020年冬季（6月）与2020年春季（10月）的成熟阶段2共采收50个芒果，对其重量、长度、腹径与横径、果皮及果肉的L*、C*和hº值、干物质含量、硬度、可溶性固形物（Soluble Solids, SS）、可滴定酸度（Titratable Acidity, TA）以及SS/TA比值进行了测定。研究结果显示，果实品质性状的变异系数（Coefficient of Variation, CV）介于2.1%至18.1%之间。两次采收中，变异系数最高的指标均为SS/TA比值，最低的则为果肉hº值。当设定10%的估计误差与95%的置信区间时，若要估算‘Palmer’芒果理化性状的均值，冬季需采样12个果实，春季则需14个果实。其中TA与SS/TA比值所需的样本量最大，而L*与hº值所需的样本量最小。综上，不同理化性状与生长季间的变异程度存在差异，这意味着在不同生长季中，估算不同品质性状的均值需采用不同的样本量。