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- Author or Editor: David C. Ferree x
Abstract
The problem of controlling tree growth, although existing throughout the history of fruit growing, has become more acute as economic conditions and population spread force growers to become more efficient and produce more fruit on each hectare of orchard land. In 1984, a workshop (9) was organized to address this issue and the High Density Plantings Working Group has organized three successful symposia (29, 30, 31) that have reported many studies on methods to increase efficiency.
Container-grown apple trees on a range of rootstocks were exposed to different levels of soil compaction created by changing soil bulk density. In 1998, with soil bulk densities of 1.0, 1.2, and 1.4, there was no interaction of rootstock and soil compaction for shoot growth of `Melrose' trees on 7 rootstocks. However, in 1999, with soil bulk densities of 1.0 and 1.5, a significant interaction on shoot growth did occur with six rootstocks. Shoot length of trees on M.9, M.7, and G.30 were less influenced than G.16, M.26 and MM.106. A bulk density of 1. 5 caused a decrease in dry weight of shoots, leaves, and roots of trees on all rootstocks. Compacted soil resulted in a decrease in leaf concentration of K and B and an increase in Mg and Mn.
In 1987, `Starkspur Supreme Delicious' and `Melrose' were planted on eight apomitic apple selections made in Germany by Dr. Hanna Schmidt for use as rootstocks and compared to trees on M.7. Selection 2, was the most precocious, followed by trees on M.7, with selections 1 and 7 being less precocious than M.7. Selections 2 and 8 were 25% larger than M.7, while 1, 3, 4, and 7 were similar in size and 5 was 15% smaller than trees on M.7. Selections 2 and 8 had the highest cumulative yields/tree, followed by trees on M.7, with all other selections having lower yields. Internal bark necrosis (IBN) developed on the `Delicious' trees, with the most-severe symptoms on selections 1, 3, 4, 5, 6, and 7, with less-severe symptoms on 8 and very little present on trees on M.7. IBN was correlated with leaf Mn levels. In 1995, the highest density of flowering spurs occurred on M.7 and selections 3 and 7, with lower densities in selections 2 and 5. Selection 2 had the highest density of non-fl owering spurs, followed by selection 5, with all others having lower densities similar to trees on M.7.
The apple (Malus ×domestica Borkh.) cultivars Starkspur Supreme Delicious and Melrose were planted in 1987 on eight apomictic apple rootstock selections made in Germany by Dr. Hanna Schmidt and on M.7. Selections 2 [M. hupehensis (Pamp.) Rehd. parentage] and 8 [M. sieboldii (Regel) Rehd. parentage] were similar to M.7 in precocity, cumulative yield per tree, and yield efficiency, while the other selections with M. sargenti Rehd. in their parentage were slower to flower and had lower yields and yield efficiencies. Selections 2 and 8 tended to result in larger trees than M.7, while the selections with M. sargenti parentage were generally similar to M.7 in size. Except for trees on M.7 and selection 2, `Starkspur Supreme Delicious' developed more severe symptoms of internal bark necrosis (IBN) than did `Melrose', which normally does not show IBN. However, `Melrose' showed IBN symptoms on selections with M. sargenti parentage. IBN symptoms were positively correlated with leaf Mn concentrations. Influence of rootstocks on other nutrient elements, although significant, were small compared to the effect on Mn. A significant interaction occurred between cultivar and rootstock in their effects upon branch morphology, mostly because fewer flowering spurs and more vegetative spurs were observed on `Melrose' than on `Starkspur Supreme Delicious' when grafted on Selection 2. These apomictic selections offered no advantage over M.7 as rootstocks for apples.
Abstract
Root-pruning young greenhouse-grown MM.111 apple trees decreased leaves per tree, total leaf area, and dry weight of leaves, shoots, and roots. Root pruning had no influence on the carbohydrate fractions in the leaves or shoots, but caused an increase in soluble and insoluble fractions in the roots. No interaction occurred between root pruning and number of trees in the container. As number of trees per container increased, leaf, shoot, and total dry weight per plant decreased. Root pruning decreased shoot growth for 3 weeks after root pruning, with a return to the unpruned shoot growth rate in the 4th week. Photosynthesis and transpiration were reduced by root pruning, but not affected by tree density.
In 1987, `Smoothee Golden Delicious' (`Smoothee') and `Lawspur Rome Beauty' (`Lawspur') apple (Malus domestica Borkh,) trees were planted and trained as central leaders or palmette leaders on M.7 and Mark rootstocks or were planted as slender spindles on Mark rootstocks. `Smoothee' trees were larger and had consistently greater yields and production per unit trunk cross-sectional area (TCA) than `Lawspur' trees. Slender spindle trees had lower early yields per tree and TCA but had greater cumulative yields per hectare than trees in the other training systems. In the fifth and sixth growing seasons, `Smoothee' trained as palmette leaders tended to have higher yields per hectare then central leader trees. Training system had little influence on `Lawspur' tree yields. Limb bending in 1989 increased flower density in 1989 and 1990. Cumulative yield per hectare increased 11% as a result of limb bending of trees on Mark rootstock, but bending had no influence on trees on M.7 rootstock. `Smoothee' on Mark had higher cumulative yields per hectare with the palmette leader and central leader than either `Smoothee' on M.7 in either training system or any combination with `Lawspur'.
`Melrose'/M.26 apple (Malus domestics Borkh.) trees were mechanically root-pruned annually for 9 years at bloom to a 25-cm depth at 80 cm from the trunk on two sides. An evaluation of the number of roots of four size categories on the exposed wall of a 1.2 x 2-m trench located 1 m from the trunk indicated that root pruning caused a reduction in all root size categories. Roots < 1 mm in diameter were reduced 20% by root pruning, while the reduction in larger roots was nearly double this amount. The effect of root pruning on root distribution was greatest in the top 30 cm of soil, parallel to the location of the root-pruning cut. Roots below 30 cm were unaffected. The number of roots in all size categories in samples taken parallel and perpendicular to the row decreased linearly with soil depth.
`Jonathan'/M.26 apple (Malus domestics Borkh.) trees were root-pruned annually on two sides, 60 cm from the trunk, to a depth of 40 cm for 6 years while dormant, at bloom, or in mid-June. Root pruning reduced terminal shoot growth by ≈30% in 1985-89 with no influence in 1990. Cumulative yield was reduced by root pruning at bloom (14%) or mid-June (20%), and cumulative yield efficiency [kg·cm-2 trunk cross-sectional area) was reduced by root pruning with no difference among pruning times except in 1 year, where abundant moisture throughout the season appeared to negate the effect. The intensity of biennial bearing was reduced by root pruning with no relationships to time of pruning. Root pruning resulted in a decrease in large fruit and an increase in small fruit in 3 of the 6 years. A covariant analysis with yield showed that root pruning reduced average fruit size. Root-pruned trees produced firmer fruit with an increased soluble solids concentration and had less preharvest drop than nonpruned trees. Under severe drought conditions in 1988, root pruning reduced net photosynthesis and transpiration; supplemental water (57 liters·week-1) increased transpiration and fruit size at harvest.
Abstract
Trees of ‘Golden Delicious’ apple (Malus domestica Borkh.) were established in 1973 in the following orchard management systems: slender spindle (SS), trellis (TR), interstem hedgerow (IH), and pyramid hedgerow (PH). Spur quality and percent photosynthetic photon flux (PPF) transmission declined from the top to the bottom of the canopy of all systems. The three conical central leader type trees (SS, IH, PH) produced a quarter of their fruit on or close to the central leader, while the palmette-shaped TR produced 60% in the center sections along the wire trellis. There was no difference between vertical fruit distribution in trees in the more intensive systems (SS, TR), but the larger trees (IH, PH) produced twice as much fruit in the top half of the canopy as in the bottom half. Trees in the SS had a lower percentage of PPF transmission values within the canopy than trees in the TR systems. Trees in IH generally had higher PPF transmission values within the canopy than the larger PH trees. The number of leaves per spur and specific leaf weight of spur leaves generally followed the light distribution pattern, and trees in the TR and IH systems had higher-quality spurs than the SS and PH systems. The SS and TR systems appeared more responsive to the orientation of the sun, having higher light transmission values on the east side of the canopy in the morning and west side in the afternoon, than the IH or PH systems.
`Melrose'/M.26 apple trees were root pruned annually for 8 yrs at full bloom on 2 sides to a depth of 25-35 cm. Spacial distribution was determined by counting roots on the exposed wall (2m × 2.5m area) of a trench and classifying them into 4 size classes. Root pruning caused a reduction in the total number of roots and the ratio of large to small roots in the 0-30 cm soil depth on the side of the tree that had been root pruned. Total number of roots declined in root pruned trees 60 and 90 cm from the trunk in the sample taken perpendicular to the root pruning cut, but not on the side parallel to the root pruning cut. Root number in all 4 size classes declined with depth and exhibited significant linear and quadratic patterns.