`Newtown' apples (Malus domestics Borkh.) treated weekly with urea at 10 g·liter-l or Ca(NO3)2 at 7.5 g·liter-1 for 5 consecutive weeks from late August were greener at harvest and during storage than comparable control fruit. A postharvest dip in Nutri-Save, a polymeric coating, was better for retention of skin greenness than a dip in diphenylamine and both gave greener apples than control (nondipped) fruit. Fruit treated with Ca(NO3)2 displayed lesions that were larger and more numerous than typical bitter pit in the control fruit.
P. Parchomchuk and M. Meheriuk
Pulsed application of overtree irrigation for evaporative cooling of `Jonagold' apples (Malus domestica Borkh.) reduced visible solar injury by 15.8% (1991) and 9.4% (1992). Maximum fruit surface temperature was reduced by 8.1 °C on a day when the average surface mean of nonsprayed fruit rose to 45.6 °C. Air heated more slowly than the exposed fruit surface and was cooled only 1 to 2 °C by overtree irrigation. Cooling did not affect fruit size, firmness, or redness but reduced soluble solids concentration and increased titratable acidity. Storage breakdown was unaffected in the first year but was reduced by 6.0% in the second year.
M. Meheriuk, D.-L. McKenzie, and L. Veto
Electron microscopic studies were conducted on `Sue', `Lapins' and `Van' sweet cherry cultivars which have a high, moderate and low resistance to rain cracking, respectively. Epidermal and hypodermal cells showed differences in size and number. Sue, the resistant cultivar, contained an additional thin elongated cell rich in protein matter, in the hypodermal layer. The three cultivars also showed differences in the cell walls and vacuoles. However, mineral content of the epidermal and hypodermal layers showed no relationship to incidence of fruit cracking.
W.D. Lane, M. Meheriuk, and D.-L. McKenzie
Fruit were studied to determine if anatomical and physiological features explain the difference in susceptibility to rain-induced cracking of the sweet cherry (Prunus avium L.) cultivars Sue (resistant), Lapins (moderately resistant), and Van (susceptible). Water uptake as a percentage of fruit weight at cracking tended to be high in `Sue', medium in `Lapins', and low in `Van' and was related to the percentage of cherries remaining sound after 4 hours of immersion, suggesting that this trait is a factor in determining resistance. Mesocarp cells of `Sue' were more rectangular in section than those of the other cultivars. Skin elasticity and thickness of the cuticle did not explain resistance of `Sue' to cracking. Magnesium, copper, and phosphorus mineral contents were not related to cracking susceptibility, but the content of calcium, which influences cell wall integrity, in the epidermis of `Sue' was lower than in `Van'. Calcium content was not different in the hypodermal cells of the two cultivars. None of the anatomical features examined in this study explain the resistance to fruit cracking of `Sue'.
W.D. Lane, D.-L. McKenzie, and M. Meheriuk
Nodules associated with the main cortical vascular bundles in fruit of the `Gala' apple (Malus ×domestica Borkh.) strains `Royal' and `Regal' were observed in several growing seasons. The nodules were found in 68% (n = 586) of the fruits examined, with a mean of 2.5 nodules per fruit. The nodules were first detected in developing fruit 2 months after bloom and were normally 1-2 mm in diameter by commercial harvest maturity. The nodules, like the vascular bundles, were pale green. They were inconspicuous at first, but became conspicuous and unattractive and changed to brown or red as the fruit became overmature. Nodules in the fruit of the `Gala' × `Splendour' hybrid `8S 27-2' were dark brown or red at picking maturity, and occurred with high frequency. Nodules were also observed in `Splendour', but were small, pale green, and infrequent in this cultivar. Microscopic examination of the nodules revealed that they typically contained a central cavity surrounded by a lignified wall with small pigmented cells outside the wall adjacent to the cortex. Low-frequency irrigation cycle times generally promoted the development of nodules in both `Gala' strains but nitrogen treatments did not affect nodule frequency in `Royal Gala'. Mean fruit nodule frequency tended to be higher, overall, in `Regal Gala' (3.9) than in `Royal Gala' (1.4).
M. Meheriuk, A.P. Gaunce, and V.A. Dyck
`Golden Delicious', `Delicious', and `Spartan' apples (Malus domestics Borkh.) showed a high, moderate, and low tolerance, respectively, to methyl bromide fumigation. Incidence of external and internal disorders increased, in most instances, with longer storage periods after fumigation treatments and with longer exposure times to the fumigant. Dips in diphenylamine before fumigation reduced, but did not prevent, disorders. Fumigation had little effect on firmness and no effect on soluble solids content or titratable acidity. Methyl bromide concentrations with a low risk of disorder development were 32 to 64 g·m-3 for `Golden Delicious', 32 to 48 g·m-3 for `Delicious', and 32 g·m-3 for `Spartan', all at 10C for 2 hours.
W. David Lane, M. Meheriuk, and R.A. MacDonald
M. Meheriuk, D.-L. McKenzie, G.H. Neilsen, and J.W. Hall
Four green apple (Malus domestica Borkh.) cultivars, `Granny Smith', `Mutsu', `Newtown', and `Shamrock', were subjected to a factorial experiment of two rates of nitrogen fertilization and three concentrations of foliar urea sprays for 4 years. The higher rate of N (160 kg N/ha) had no effect on ground color or fruit quality relative to the lower rate of 80 kg N/ha. Urea sprays enhanced green pigmentation in `Granny Smith' and `Newtown' at harvest and retarded yellowing of fruit in all cultivars during air storage at 0C. Response was similar for urea at 0.5% and 1%, and urea sprays did not adversely affect quality. Urea sprays increased fruit N by 23% and 47% for the 0.5% and 1% concentrations, respectively.
M. Meheriuk, D.-L. McKenzie, B. Girard, A.L. Moyls, S. Weintraub, R. Hocking, and T. Kopp
Kilogram quantities of `Sweetheart' cherries were stored in HDPE perforated bags (1993, 50.8 μ thickness, OTR = 750 ml·m–2·day–1) or in nonperforated bags (1994, 11 μ thickness, OTR = 5196 ml·m–2·day–1) at 0C. Samples were removed at 1, 2, 4, and 6 weeks of storage and evaluated for fruit and sensory quality. Bag atmospheres after 6 weeks of storage were 10% CO2 and 4.6% O2 for the perforated bags and 3.5% CO2 and 6.6% O2 for the nonperforated bags. Fruit brightness, firmness, and titratable acidity declined during storage. Skin color tended to be redder with the longer storage periods. Sensory evaluation in 1993 showed a decline in overall appearance and flavor with time, but texture and juiciness did not change. Acceptability remained high for the first 4 weeks of storage but dropped at week 6. Surface pitting was noticeable at weeks 4 and 6, particularly from stem bruising.