The effects of rootstock on `Delicious' (Malus domestics Borkh.) apple ripening, quality, size, mineral composition, and storability were studied over 4 years. Removal of the effects of crop load by analysis of covariance suggested that M.27 EMLA advanced fruit ripening and that M.7 EMLA delayed fruit ripening. Ott.3, M.9, MAC 9, OAR 1, M.9 EMLA, and M.26 EMLA either were inconsistent in their effects on ripening or consistently-resulted in an intermediate time of ripening. Fruit size consistently was largest from trees on M.9 EMLA and smallest from trees on OAR 1. Fruit from trees on MAC 9 generally had relatively high Ca contents, and fruit from trees on OAR 1 had relatively low Ca concentrations. The effects of rootstock on storability appeared to be related to their effects on maturity arid Ca levels.
In 1990, a trial was established at 17 locations in the United States and Canada including the scions `Golden Delicious', `Jonagold', `Empire', and `Rome” and the rootstocks M.9 EMLA, B.9, Mark, O.3, and M.26 EMLA. In 1994, trees on M.26 EMLA were the largest and trees on B.9 and those on Mark were the smallest, regardless of scion. Trees on M.9 EMLA were intermediate. `Golden Delicious' and `Empire” trees on O.3 were larger than those on M.9 EMLA. `Jonagold' and `Rome' trees on O.3 were similar in size to those on M.9 EMLA. With all scions, B.9 and Mark resulted in the lowest cumulative yields. With `Jonagold', `Empire', or `Rome' as the scion, O.3, M.26 EMLA, and M.9 EMLA resulted in the greatest and similar yields. With `Golden Delicious' as the scion, however, trees on M.9 EMLA yielded only as much as those on B.9 or Mark. Trees on B.9 and those on Mark were the most yield-efficient, regardless of scion. `Golden Delicious' and `Rome' trees on O.3 were similar to those on B.9 and those on Mark, but `Jonagold' and `Empire' trees on O.3 were less efficient than those on B.9 or on Mark. Overall, M.26 EMLA resulted in the lowest efficiency; however, M.9 EMLA resulted in more efficient trees only with `Empire' as the scion. Participants include: J.L. Anderson (Utah), W.R. Autio (Mass.), J.A. Barden (Va.), G.R. Brown (Ky.), P.A. Domoto (Iowa), D.C. Ferree (Ohio), A. Gaus (Colo.), R.L. Granger (Quebec), R.A. Hayden (Ind.), F. Morrison (Kan.), C.A. Mullins (Tenn.), S.C. Myers (Ga.), R.L. Perry (Mich.), C.R. Rom (Ark.), J.R. Schupp (Maine), and L.D. Tukey (Pa.).
`Summerland Red McIntosh' apple trees propagated on M.9/A.2,O.3, M.7 EMLA, M.26 EMLA, M.7A. OAR1, or Mark rootstocks were planted in 1985 in a randomized complete block design with seven replications. Fruit ripening and quality were assessed in 1988-93. Internal ethylene concentrations were measured weekly throughout each harvest season. Once each season, fruit weight, starch-index value, soluble solids concentration, flesh firmness, and surface ted color were assessed on a sample of fruit from each tree. Size was smallest for fruit from trees on OAR1 or Mark, after accounting for the effects of crop load with analysis of covariance. Surface ted color was greatest for fruit from trees on Mark and least for fruit from trees on M.7 EMLA. Ripening was variable, but generally, fruit from trees on 0.3 ripened first, and fruit from trees on M.7 EMLA or M.7A ripened last. Crop load impacted ripening, but its effects were removed with analysis of covariance.
In 1990, trials were established at 13 sites including `Golden Delicious', `Jonagold', `Empire', and `Rome' apple cultivars in all combinations on M.9 EMLA, B.9, Mark, O.3, and M.26 EMLA rootstocks. After 10 growing seasons, rootstock and cultivar interacted significantly to affect trunk cross-sectional area and yield efficiency but not yield per tree or survival. Generally, trunk cross-sectional area was greatest for M.26 EMLA, followed by O.3, M.9 EMLA, B.9, and Mark. However, differences between B.9 and Mark and between M.9 EMLA and O.3 varied with cultivar. B.9 was 34% to 46% larger than Mark with `Golden Delicious' and `Empire,' but they were similar for `Jonagold' and `Rome.' O.3 was 27% larger than M.9 EMLA with `Golden Delicious' and `Empire,' they were similar for `Rome', and O.3 was 12% smaller than M.9 EMLA with `Jonagold'. M.26 EMLA resulted in the greatest cumulative yield per tree, followed by O.3, M.9 EMLA, B.9, and Mark. Generally, cumulative yield efficiency (1992–99) was greatest B.9 and Mark and least for M.26 EMLA. M.9 EMLA and O.3 were similar and intermediately efficient. However, differences between B.9 and Mark and between M.9 EMLA and O.3 varied with cultivar. M.9 EMLA and O.3 were similarly efficient with `Golden Delicious', `Jonagold', and `Rome,' but M.9 EMLA was 11% more efficient than O.3 with `Empire'. B.9 and Mark were similarly efficient with `Golden Delicious' and `Jonagold', but Mark was 15% more efficient and 25% less efficient than B.9 trees with `Empire' and `Rome', respectively. Site played an important role, but survival was best for B.9 and poorest for O.3. Cooperators included: J.L. Anderson, W. Autio, J. Barden, G. Brown, R. Crassweller, P. Domoto, A. Erb, D. Ferree, A. Gaus, R. Hayden, P. Hirst, F. Morrison, C. Mullins, J. Schupp, and L. Tukey.
The effects of rootstock on `Delicious' apple maturity, quality, size, mineral composition, and storability were studied over a 4-year period. Removing the effects of crop load and crop load within year by analysis of covariance produced results suggesting that M.27 EMLA and Ott.3 advanced fruit maturity and that M.7 EMLA delayed fruit maturity. M.9, MAC 9, OAR 1, M.9 EMLA, and M.26 EMLA either were inconsistent in their effect on maturity or consistently resulted in an intermediate maturity. Size, after adjusting for the effects of crop load and crop load within year, was consistently high for fruit from trees on M.9 EMLA, and lowest for fruit from trees on OAR 1. After adjusting for fruit size, fruit from trees on MAC 9 generally had high Ca contents, and fruit from trees on OAR 1 had low Ca contents. The effect of rootstock on storability appeared to be secondary and related to maturity and Ca level.
Aminoethoxyvinylglycine (AVG) applied to apple trees (Malus domestica Borkh.) 1 week before harvest suppressed C2H4 production and delayed C2H4 peaks of fruit kept at room temperature. Early season cultivars (‘Early McIntosh’, ‘McIntosh’) were less affected by AVG than were late-season cultivars (‘Cortland’, ‘Royal Red Delicious’). While ripening was significantly delayed, maturation of ‘Puritan’ apples, as judged by changes in firmness, peel chlorophyll concentration, percent soluble solids, flesh starch concentration, and titratable acidity, was unaffected by AVG tree-sprays applied up to 6 weeks before harvest. Addition of C2H4 to the storage atmosphere accelerated ripening of AVG-treated fruit, whereas their ripening was slowed by storage at 0°C rather than at 3.3°.
Apple trees (Malus domestica Borkh.) were notched with a hacksaw blade by removing a 2-mm-wide strip of bark from directly above a bud. The cut extended down to the secondary xylem and around about one-third of the circumference of the stem. The most effective time to notch was ≈2 to 4 weeks before full bloom. Notching was most effective at inducing shoot growth from buds on the top of a branch, less effective for buds on the side, and least effective for buds on the underside of a branch. On untreated controls, the most shoots grew from the upper one-third of 1- or 2-year-old growth, and very few shoots developed buds on the lower one-third. If a bud was notched, however, the pattern was similar and incidence of shoot development was high. The percentage of notched buds that developed into shoots was not influenced by wood age.There was a positive, linear relationship between bud size and the percentage of buds growing into lateral shoots and between bud size and the length of those lateral shoots. Over all years, experiments, and cultivars, notching increased shoot production ≈600%.
The effects of summer pruning on the yield and quality of apples (Malus domestica Borkh.) from mature `Rogers McIntosh'/M.7 trees were assessed in 1986-88. Summer pruning from 1 July through 1 Sept. enhanced red coloring and increased the percentage of the crop graded U.S. Extra Fancy. Fruit weight was not altered by summer pruning. Total yield was reduced by summer pruning only in 1 year, however, in no year was the harvested yield reduced. The portion of the crop that was picked in the first harvest was increased by summer pruning. Dormant-pruning time was decreased by summer pruning, and the total time required for pruning was increased only 1 of the 2 years where it was measured. Summer pruning and daminozide treatment significantly increased the estimated net returns.
Benzyladenine (BA) stimulated lateral branching on young apple (Malus domestica Borkh.) trees at concentrations as low as 100 mg·liter-1. BA reduced lateral shoot length indirectly through increased intersboot competition, whereas daminozide reduced lateral shoot growth as a direct effect of the chemical inhibition. Daminozide reduced the number of spurs that were induced by BA to grow into lateral shoots. BA reduced the size of terminal buds on spurs that were stimulated to grow into lateral shoots. When daminozide was included with BA, spur quality was increased, as determined by Increased bud size. The positive effect of daminozide on BA-treated spurs was indirect, and other growth retardants used in combination with BA may be equally effective at improving spur quality. It may not be possible to stimulate lateral branching with BA on young trees just coming into production without causing an unacceptable amount of thinning. However, on bearing `Empire' trees, lateral shoot growth was increased with BA while still achieving an appropriate level of thinning. In general, there was no advantage to applying BA in a split application. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)]; butanedioic acid mono(2,2-dimethylhydrazide) (daminozide).
Postchilling ion leakage, respiration, and C2H4 biosynthesis were used to measure the degree of chilling injury to fruit of tomato (Lycopersicon esculentum Mill. ‘Heinz 1350’). Chilling sensitivity, as measured by ion leakage, first declined as the tomatoes began to ripen and then increased during the late stages of ripening. Both C2H4 biosynthesis and respiration rate were stimulated during the chilling response early in ripening. In the nonripening mutant, nor, chilling sensitivity did not show the early decline but showed the increase during senescence. Variation in chilling sensitivity during tomato ripening was biphasic, with a decline at the onset of ripening followed by a senescence-related increase. It is proposed that the latter may be due to an increase in membrane viscosity.