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  • Author or Editor: A. N. Roberts x
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Abstract

Trunk cross-sectional area was found to bear a linear relationship to total above-ground weight of apple trees. From these data, it is suggested that trunk measurements can be used to estimate the potential bearing surface of any orchard tree as long as it has not been pruned heavily to prevent crowding. This relationship permits the calculation of yield efficiency as fruit weight per cm2 trunk cross-section. Estimates were made of maximum bearing surface potential (tree weight) per acre (as cm2 trunk area) for several kinds of tree fruits and nuts.

Open Access

Abstract

The Mugo or Swiss mountain pine is one of the most popular evergreen shrubs for modem landscaping. Mugo pines include the type species (sometimes referred to as var. mugo or var. mughus) and 3 additional geographical varieties pumilio (Haenke) Zenari, rostrata (Ant.) Gord., and rotunda (Link) Gord. (1, 8). The most desirable dwarf forms for landscape use are derived from p. mugo var. pumilio. The other 2 botanical varieties are usually of arboreal size.

Open Access

Abstract

‘Thompson Seedless’ grapes (Vitis vinifera L.) were trained to heights of 1.4, 1.7, and 2.0 m with and without an 0.6-m crossarm. Data were collected from 4 seasons beginning in 1969. Within treatments variability was usually too great to reveal significant differences among treatment means for most parameters measured within a single year. Analysis of the 3-year combined results revealed that the highest trellis resulted in most yield, most clusters, and most berry sugar per vine. Vines on the lowest trellis had the least pruning brush wt. Vines with crossarms had higher wt per berry, soluble solids, sugar, and wt brush per vine than did vines without crossarms.

Open Access

Abstract

Growth and yield of ‘Montmorency’ cherry varied greatly both within and between species of rootstock clones. Trees on FI2/1 mazzard (Prunus avium L.) were very vigorous and less productive than those on other stocks. Some growth control was found within each species or hybrid group but was most pronounced with P. mahaleb L. clones PI 193688, PI 163091 and PI 193693. Yield efficiency was not necessarily related to tree size but tended to be better with smaller trees. The 3 P. mahaleb clones listed above and the vigorous clones OCR-3 (P. mahaleb × P. avium) and PI 194098 (P. mahaleb) had high yield efficiencies. Trees on F12/1 and P. mahaleb PI 193703 had the lowest yield efficiencies. Based upon ideal orchard spacing for tree size, calculated annual yields exceeded 10 metric tons per ha for 6 of the clonal stocks.

Open Access

Abstract

‘Golden Delicious’ and ‘Starking Delicious’ apple (Malus domestica Borkh.) on Mailing 9 (M 9) rootstock were planted in 1956 in alternate rows 4.57 m (15 ft) apart, with in-row spacings of 1.22, 1.83 and 2.44 m (4, 6, and 8 ft). Average annual yield was higher at the closest spacing (1794 trees/ha) during the entire 18 years of the test. The pattern of yield was similar for the 2 cultivars but was higher for ‘Golden Delicious’ because of the lower fruit set of ‘Starking’ in some years due to adverse weather. Pruning during the last 6 years of the test was done by mechanical shearing of tops and sides, with no detailed pruning within the fruiting wall. This type of pruning on dwarf trees resulted in adequate fruit size, color, and quality with normal fruit thinning practices.

Open Access

Abstract

Tests in 11 plots of ‘Italian’, ‘Early Italian’, and ‘Brooks’ prunes showed several influences of rootstock on tree growth, flowering, yield, fruit size, maturity, and quality. Of the 6 Prunus species represented by the 19 rootstocks tested, myrobalan roots usually resulted in larger trees, heavier bloom, but lower yield efficiency than did peach roots. Trees on Marianna and several P. domestica L. roots varied in size and yield, but most of them had greater bloom density than trees on peach root. ‘Italian’ fruit firmness varied inconsistently with rootstock. ‘Early Italian’ fruits were firmer on peach than on other roots, but ‘Brooks’ fruits were less firm on peach than on other roots. The tendency for internal fruit browning of ‘Italian’ was greater on plums than on peach roots. Other fruit maturity and quality factors varied by cultivar and by individual rootstock. Fewer trees on peach root died from trunk canker (Pseudomonas syringae van Hall) than did those on several clonal plum roots, but some plum-rooted trees outgrew the canker and survived as well as trees on peach stock.

Open Access

Abstract

Plantings of the ‘Italian’ prune (P. domestica L.) were established on seedling peach (P. persica L. Batsch) and clonal Myrobalan 29-C, B, 2-7 (P. cerasifera, Ehrh.); Marianna 4001, 2623, 2624 (P. cerasifera × Munsoniana?, Wight and Hedr.); and St. Julien A (P. insititia L. Bullace) rootstocks in 7 orchard sites in Oregon. Leaf samples were collected in the years 1968 to 1970 and analyzed for element content. Trees with plum rootstocks had greater leaf N, K, Mn, and Zn and slightly less B and Mg than those on peach. Plum clones, Myrobalan 29-C, Myrobalan B, and St. Julien A, were more efficient in the uptake of Ca. There were positive correlations between N and Ca, N and Mg, N and B, N and Zn, Ca and Mg, Ca and B, and Mg and B for most of the stocks. There was a negative correlation between K and Mg for Myrobalan 2-7 and the 3 Marianna clones. Myrobalan B and Marianna 2623 and 2624 had a negative corrleation for K and Ca whereas St. Julien A had a positive correlation.

Open Access
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Abstract

Recent interest in the production of Rhododendrons as potted plants has raised many questions concerning propagation, dormancy, flower initiation, and general patterns of growth and development. Cathey (1) has shown that general growth habit may be altered to give a more compact plant through the use of Phosphon or by B-nine. He found further that flower initiation could be stimulated after the production of 4-5 flushes of growth instead of the normal 8-9 flushes required under natural conditions, thus making this plant useful as a potted plant. Myhre (3) showed that large applications of phosphate fertilizer increased the number of terminal apices initiating flowers in ‘Cynthia’. In 1920, work in the Netherlands by Luyten and Versluys (2) indicated that leaf and flower initiation occurred early in the growth cycle, May 31 to June 8.

Open Access

Abstract

We determined origin and time required for development of callus and root initials in Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stem cuttings from stained sections. Callus originated principally from the vascular cambium, but phloem and xylem parenchyma also contributed. Continuous cell division, elongation, and differentiation within callus gave rise to root primordia. Once formed, root primordia elongated within 15–30 days.

There was no apparent difference in tissue origin of adventitious roots in stem cuttings collected from sheared juvenile or sheared or non-sheared adult trees during pre-, true, and post-dormancy. Time required for callus formation and root initiation varied with degree of bud dormancy. Rooting was low during pre-, almost none during true, and highest during post-dormancy.

Open Access
Authors: and

Abstract

Yearling ‘Nellie White’ Easter lily plants were subjected to various air and soil temperature combinations to determine temperature requirements for 6 growth phases, each of one-month duration. An air and soil temperature of 24°C favored rapid leaf unfolding, stem elongation, and flower expansion with concomitant depletion of primary scales. After flower buds were visible, soil temperature had no appreciable effect on their rate of expansion; air temperature was the controlling factor. Leaf unfolding rate, stem length, and flower bud size were of equal value in monitoring crop development. Secondary scale initiation and development during the prebloom period was positively related to soil temperature rather than air temperature and was maximum at 24°. The rate of scale initiation progressively decreased from first appearance of the secondary meristem until anthesis of the primary axis. High soil temperature decreased the diameter of the secondary (daughter) axis apical meristem at any time prior to appearance of flower buds on primary axis (buds visible).

Open Access