บทคัดย่องานวิจัย

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Prediction of optimum harvest date of Jonagold.

Jager, A. de; Roelofs, F. P. M. M.;

COST 94. The postharvest treatment of fruit and vegetables. Determination and prediction of optimum harvest date of apples and pears. Proceedings of a meeting, Lofthus, Norway, 9-10 June 1994. Year: 1996 Pages: 21-31 Ref: 9 ref.

1996

บทคัดย่อ

Prediction of optimum harvest date of Jonagold.

Over 5 years (1989-1993), fruits of apple cv. Jonagold were sampled in the southern and southwestern parts of the Netherlands each year during a period of about 8 weeks. At the end of the sampling period fruits were harvested weekly at 4 dates and subsequently stored at 1 deg C, 1.2% O2 and 5% CO2. Following storage (7-8 months) and shelf life (7 days at 10 deg + 7 days at 20 deg ), quality was evaluated by different methods: (1) taste test plus measured quality, (2) measured quality only, (3) tasted quality only and (4) physiological weight loss (PWL). Using these poststorage data, real optimum harvest dates (OHD) were calculated for each orchard and used to calculate the value of different harvest indexes at OHD. In addition to the 'Streif-index' (firmness/(refraction x starch stage)), the modified index PFW-index-1 (firmness x (11 - starch stage)/refraction), the single characteristic 'starch stage' and PFW-index-2 (firmness x ground colour/refraction) were tested. Predictions for years 4 and

 5 using models based on data of the first 3 years showed best agreement with real OHD determined on the basis of taste tests on the one hand and measured level of firmness, refraction and acidity on the other (1:1). Using this method of real OHD estimation both the 'Streif-index' and the PFW-index-1 showed best agreement between predicted and measured OHD for 1992 and 1993. The model, updated with the data of years 4 and 5, can be used to predict mean OHD for a region but needs further elaboration to give predictions for individual orchards.