Optimum Harvest Date Research Articles

EFFECTS OF SUCCINIC ACID 2,2-DIMETHYL HYDRAZIDE (ALAR) AND 2-CHLOROETHYLPHOSPHONIC ACID (ETHEPHON) ON ABSCISSION AND STORAGE QUALITY OF McINTOSH APPLES

McIntosh apples that had been sprayed at the end of July with Alar as recommended commercially for preharvest drop control, were later treated with ethephon at 400 and 800 mg/liter, 6 and 3 days before optimum harvest date. Results were compared with untreated fruit and with fruit from trees sprayed with Alar alone. Measurements were made of abscission and firmness as well as CO2 and ethylene (C2H4) evolution. Treated fruit had a respiration rate greater than that of the control at harvest time. Ethephon treatments resulted in fruit that was firmer than Alar-treated or control fruit. No differences were noted among treatments with regard to pH, total acidity, percent soluble solids, or storage disorders of the fruit.

A New York Study of ‘Mcintosh’ Apple Optimum Harvest Dates1

Abstract In a 9-year study of ‘Mcintosh’, 85 observations were made of the optimum harvest date for apples destined for storage. Statistical analyses showed that 75% of the variation in the length of the period from bloom to harvest was associated with seasonal differences in dates of bloom and average mean daily temperatures during the period from bloom + 30 days.

Studies on apple maturity

In McIntosh apple fruits, investigations were carried out on the reasonability of application of respiratory climacteric to the determination of the optimum harvest date for storage and the significance of determination of flesh firmness, soluble solids and acid contents for maturity determination. And a new method for maturity determination was devised on the basis of the pattern of the respiration rate variation of a fruit arising from the change of period from picking till measuring. Here, a mention must be made on the terms of RC and rc. The former stands for respiratory climacteric“on the tree”estimated from the respiration rates of fruits picked at different dates, and the latter dose that of at each fruit“off the tree.”1. Considerable individual variation was observed on the respiration rate on a weight basis in fruits picked at the same time, but this may be neglected by using fruits of uniform appearance.2. When the respiration rates of each picking for periods of about ten days following harvest were measured, all stages of respiratory climacteric were found at earier pickings but rc-minimum (min.) was not found later and neither rc-min. nor rc-rise at last as fruits were getting ripe.3. In order to estimate RC, fruits were picked ten times and the respiration rates were measured. In such cases, the longer the time from picking till measuring became, the sooner RC appeard.4. The usual method for RC estimation requires respiration measurements on the fruits picked several times at successive dates. And an estimation on the time of RC-min. cannot be made before RC-rise appears. Besides, RC pattern varies with the time from picking till measuring. It seems, therefore, that it is not a suitable method for the determination of the best picking date of the fruit for storage. On the contrary, if the difference of the respiration rate between two measurements carried out different hours after picking is applied, RC estimation becomes possible by only one picking. In other words, when the respiration rate measured 24 hours after harvest is smaller than that done after six hours and larger than after 48 or 96 hours it is before RC-min., and in the reverse case it is after RC-min.5. No index to maturity was found in flesh firmness or acid content. The variation of soluble solids proved to be taken as a reliable index to maturity. But it has no practical use because it does not allow of the determination being repeated on the same fruit and is involved in considerable individual variations.

Maturation in peas. 2. Spread in maturity.

A good impression could be obtained of the spread in maturity within a crop of green peas at 'optimal harvest date' by applying the method described in the previous abstract. It was found that differences between varieties existed, but also that varieties showed differences in reaction to growing conditions. At optimum harvest date an appreciable proportion of pods contained peas which were too old, but a considerable proportion of other pods contained peas which were far too young. Therefore, under commercial conditions of once-over harvest, the actual yield of good-quality peas remained far below the potential yield.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)

A Study of the Relationship Between Optimum Harvest Dates for Storage and the Respiratory Climacteric Rise in Apple Fruits1

Abstract ‘McIntosh’ and ‘Cortland’ fruits were harvested at 3—4 day intervals and ‘Delicious’ and ‘Golden Delicious’ fruits were harvested at 5 day intervals in several seasons. The respiration rate was measured 24 hr after each harvest in order to locate the position of the fruit on the respiratory climacteric curve. The optimum harvest dates for each variety were determined by evaluations of the quality and condition of the fruit after removal from storage. Optimum harvest dates were not found to be associated with any definite position on the climacteric curve.

Relationships Between NO−3‐N in Petioles During the Growing Season and Yield Components of Sugar Beets (Beta vulgaris)1

AbstractSugar beets grown at 3 levels of nitrogen fertilizer and 4 irrigation frequencies were harvested on 3 different dates. Petiole samples were taken at about monthly intervals and analyzed for NO3−‐N. These nitrogen values were correlated with sugar yield at each harvest to determine the suitability of such analyses in predicting an optimum harvest date. The irrigation treatments had no effect on yield of roots or sugar. High nitrogen rates increased beet root yields at the last harvest date and decreased the sugar percentage at all harvest dates. However, NO3−‐N content of the petioles was not sufficiently correlated with sugar yields to be useful in predicting an optimum harvest time for maximum sugar production. With progressively later harvest dates, sugar yield per acre showed increased correlation with beet yield and decreased correlation with percent sugar.

Seed ripening in grasses. I. Changes in carbohydrate content

1. In grass seed crops accurate assessment of the optimum harvest date is made difficult by the lack of knowledge of seed ripeness. In order to define ripeness in physiological terms studies have been initiated the first of which is described in this paper.2. Samples of Aberystwyth S. 321 perennial ryegrass (Lolium perenneL.), S. 143 cocksfoot (Dactylis glomerataL.), S. 48 and S. 352 timothy varieties (Phleum pratense L.) were taken at 3-day intervals from inflorescence emergence to seed harvest. These were analysed for total 80 % ethanol soluble carbohydrates (TSC) reducing sugars, sucrose and starch, whilst duplicate samples were air-dried for determination of thousand seed weight and percentage germination.