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- Author or Editor: D. C. Ferree x
The impact of environmental factors on the photosynthetic potential of tree fruits is largely uncontrollable, but one can affect photo synthetic efficiency through the manipulation of various cultural practices. Application of pesticides and other chemicals; tree size and shape; mineral nutrition; and pest damage are all important factors and should be carefully considered in maximizing net photosynthesis (Pn) and ultimate tree performance.
In 1984 trees of `Starkspur Supreme Delicious' apple on 15 rootstocks were planted at 28 locations in North America according to guidelines established by The North Central Regional Cooperative Project (NC-140). The largest trees were on P.18, ANT.313, B.490 and seedling. Producing trees approximately 70% the size of seedling were rootstocks P.1 and M.7 EMLA while M.26 EMLA and C.6 were 50% the size of seedling. A group of rootstocks 30% the size of seedling or smaller were B.9, MAC.39, P.22, P.2, P.16. Rootstocks with high production efficiency were P.16, 8.9, P.22, P.2 and C.6. Rootstocks with low production efficiency similar to apple seedling were MAC.1, M.4., B.490, P.18 and ANT.313.
A study to determine the influence of 4 rootstocks, 2 propagation methods, and transplanting on the growth and flowering of young ‘Skyline Supreme Delicious’ apple trees (Malus domestica Borkh.) revealed that trees on Mailing Merton (MM) 106 resulted in the greatest annual increment of growth followed by trees on MM 111, Mailing (M) 26 and M9. The rootstock influence on growth was evident in the second growing season. In their first season, budded trees made more rapid growth than grafted trees, but grafted trees made 39% more total growth in the second season. Two seasons later the trunk circumference, total shoot growth, tree height and spread, numbers of shoots and root suckers were greater on grafted trees than on budded trees. Transplanted trees had less trunk circumference, total shoot growth, tree height and spread, numbers of shoots and root suckers than stationary trees at the end of the fourth season. Trees on M 9 and M 26 produced more flower clusters than trees on MM 106 and MM 111. Grafted trees had more flower clusters than budded trees and stationary trees had more clusters than transplanted trees.
Three hand pruning systems (annual, biennial, and triennial) and 2 combinations of mechanical hedging and hand pruning were compared on 6 cultivars of apple (Malus domestica Borkh.) on Mailing (M) 26 planted in 1968 at a spacing of 3.6 × 6 m. In general cultivars responded similarly to the pruning treatments. After 6 years the pruning treatments had no apparent influence on trunk circumference and tree height, but hedging decreased tree spread. There were similar light levels with all pruning treatments. Inserting limb spreaders and pruning annually had the highest labor requirements and was among the better treatments in inducing larger fruit size, accumulated yield/tree, yield/trunk cross sectional area and revenue/tree. Hedging plus biennial pruning had a smaller labor requirement and was equivalent to annual pruning in fruit size, accumulated yield/tree, yield/trunk cross sectional area and revenue/tree. Hedging followed by annual pruning resulted in the lowest number of fruit/tree, accumulated yield/tree and yield/trunk cross section and was considered the least desirable treatment.
Greenhouse and field-grown `Seyval blanc' grapevines (Vitis sp.) were grown with low-growing, shallow-rooted, mat-forming, ornamental perennial groundcovers, and the effect of the groundcovers on the vegetative and fruiting growth of the grapevines was evaluated. The groundcovers used in this experiment were `Kentucky-31' tall fescue (Festuca arundinacea); white mazus (Mazus japoonicus albus); english pennyroyal (Mentha pulegium); dwarf creeping thyme (Thymus serpyllum minus); strawberry clover (Trifolium fragiferum); `Heavenly Blue' veronica (Veronica prostrata `Heavenly Blue'); and a companion grass mixture of 75% perennial ryegrass (Lolium perenne) and 25% red fescue (Festuca rubra). A control treatment grown without any groundcover was also used in both the greenhouse and field experiments. All of the groundcovers reduced `Seyval blanc' total shoot length from 22% to 85% in the vineyard. Cluster size was reduced in the field from 7% to 68% by the groundcovers compared to the herbicide control treatment, and from 9% to 66% in the greenhouse experiment, but none of the groundcovers in either the greenhouse or field experiments affected the pH, total acidity, or soluble solids concentrations of the `Seyval blanc' juice. English pennyroyal was the only groundcover that reduced in the leaf area of the grapevine. Single-leaf photosynthesis of the `Seyval blanc' grapevines in the field experiment was reduced by all groundcovers except mazus and creeping thyme. Water infiltration rates were 10 to 50 times higher in the groundcovers compared to the bare soil of the herbicide control treatment. Weed growth in the field caused reduction in shoot length similar to the most competitive groundcovers. Weed growth was reduced in the early season by the english pennyroyal and companion grass, and in the late season by all groundcovers. The reduction in growth of the grapevines caused by groundcovers in the greenhouse was a reasonable screen for the affect of groundcovers in the field. The mazus treatment was the only groundcover in our experiments that coupled fast growth with low competitive ability.
Dormant, 2-year-old, own-rooted `Chambourcin' grapevines (Vitis sp.) were subjected to two levels of root pruning (none, two-thirds roots removed) and were subsequently trained with either one or two canes. Vines were destructively harvested at bloom and after harvest when dormant to determine the effect of stored reserves in the root and competition between shoots for these reserves on vine growth and berry development. Removing 78% of the root system reduced shoot elongation and leaf area more effectively than did increasing the number of shoots per vine from one to two. Root pruning reduced the elongation rate of shoots for 45 days after budbreak, whereas increasing the shoot number reduced the shoot elongation rate for only 20 days after budbreak. A positive linear relationship was observed between leaf area per shoot at bloom and the number of berries per single cluster. These results demonstrate the importance of 1) the roots as a source of reserves for the initial development of vegetative tissues in spring, and 2) the rapid development of leaf area on an individual shoot for high set of grape berries on that shoot.
`Smoothee Golden Delicious' apple trees on nine rootstocks or interstems were mechanically root pruned annually for 9 years beginning the year after planting. Root pruning reduced trunk cross-sectional area (TCA) by 14% over the first 5 years and 22% in the last 4 years of the trial. Yield and fruit size were reduced by root pruning in most years with the fruit size effect obvious in June at the end of cell division. Interstem trees of MAC.9/MM.106 were larger than trees on M.9 and the following interstems: M.9/MM.106, M.9/MM.111, M.27/MM.111. Trees on seedling (SDL) rootstock were the largest and had the lowest yield per unit TCA and lower cumulative yield/tree than trees on M.7, MM.106, and MM.1ll. There was no interaction for any measure of growth or yield between root pruning and rootstock or interstem.
Container-grown `Chambourcin' grapevines were exposed to soil compaction created by changing soil bulk density to determine the effect of levels of compaction, rootstocks and moisture stress on mineral nutrition, leaf gas exchange and foliar carbohydrate levels. Shoot growth, leaf area, number of inflorescences and leaf dry weight decreased linearly as soil bulk density increased with the effects being significant above 1.4 g·cm-3. The early season leaf area was reduced 40% in the second season, but later leaves were unaffected by a soil bulk density of 1.5 g·cm-3. Net photosynthesis (Pn) and transpiration (E) increased linearly with increasing soil bulk density the first year, but the second year a nonlinear pattern was observed with highest rates at 1.3 and 1.4 g·cm-3. Soil bulk density of 1.5 g·cm-3 reduced number of leaves, leaf area and shoot length and advanced bloom 16 days on `Chambourcin' vines on six rootstocks with no interaction of rootstock and soil compaction. Withholding water for 8 days reduced Pn and E in all treatments, with no effect on shoot length, leaf, stem and total dry weights. Moisture stress in the noncompacted soil caused a reduction in leaf concentration of fructose, glucose and myo-inositol, but moisture stress had no effect in the compacted soil. Moisture stress caused a reduction in sucrose in both compacted and noncompacted soil. Compacting soil to a bulk density of 1.5 g·cm-3 was associated with an increase in leaf N, Ca, Mg, Al, Fe, Mn, Na, and Zn and a decrease in P, K, B, and Mo.
‘Delicious’/M9 planted in 1974 were unpruned or pruned on 3 July, 3 Aug., or 3 Sept. 1979, and at a comparable time in 1980. In the distal section, total length and dry weight of lateral shoots were greater on vertical than on horizontal limbs. Lateral shoot length and dry weight were decreased in the distal but not affected in the middle and proximal sections by pruning. Pruning and limb orientation had no effect on the distribution of dry weight in the limb sections. Time of pruning had no influence on the distribution of growth in the limb sections.
Sprays of 0.5% poly-1-p-menthen-8-9-diyl (Vapor Gard), an antitranspirant, decreased fruit size but had no influence on russet or fruit quality of field-grown ‘Golden Delicious’ apple (Malus domestica Borkh.). Laboratory experiments in growth chambers with potted ‘Golden Delicious’ apple trees indicated that: 1) Vapor Gard at concentrations of 0.25, 0.5, 1.0, and 2.0% tended to decrease net photosynthesis (Pn) and transpiration (Tr) for 1 to 7 days under optimum soil moisture conditions; 2) under conditions of low soil moisture, 2.0% Vapor Gard sprays reduced Pn and Tr significantly, but did not reduce symptoms of injury from moisture stress; and 3) Vapor Gard did not affect shoot growth over a 21-day period.