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  • Author or Editor: L. W. Grimes x
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Abstract

Certified, fresh-dug plants of ‘Apollo’ and ‘Earlibelle’ strawberries (Fragaria × ananassa Duch.) were set in single plant rows on 23 Sept., 7 Oct., 21 Oct., and 5 Nov. 1982 at in-row spacings of 7.5, 15, 22.5, and 30 cm. After harvest in 1983, plants were mowed and maintained as hill rows or mowed or not mowed for conversion to matted rows. Crown number, leaves, inflorescences and flowers per crown, fruit size, and fruit number and yield were determined in Spring 1984. Mowing had no effect on yields of matted rows, which, except from the 23 Sept. set plants, were higher than hill rows. Hill rows produced larger fruit than matted rows, but the latter had higher fruit numbers and averaged 57 % more crowns per unit area. The 23 Sept. hill row yields were higher than later plantings, but original planting date had no effect on matted row yields. Fruit number of the three later plantings of both training systems and hill row yields decreased as plant spacing increased. ‘Apollo’ had higher yields and individual yield component values than ‘Earlibelle’ in both training systems.

Open Access
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Abstract

Certified, fresh-dug plants of ‘Apollo’ and ‘Earlibelle’ strawberry (Fragaria × ananassa Duch.) were set in single plant rows on 23 Sept., 7 Oct., 21 Oct., and 5 Nov. 1982 at in-row spacings of 7.5, 15, 22.5, and 30 cm. Leaf, inflorescence, flower and fruit number per plant, and fruit size and yield were determined in Spring 1983. The highest yield and fruit numbers were obtained from the 23 Sept. plantings. Yields decreased with each delay in planting through 21 Oct., but the affected yield components varied with planting date, plant spacing, and cultivar. Total yield increased as plant spacing decreased for each planting date. Plant spacing had no effect on fruit size.

Open Access

Abstract

Paclobutrazol applied at 37 mg per plant to container-grown, own-rooted peach [Prunus persica (L.) Batsch ‘Redhaven’] trees reduced vegetative growth (compared with no treatment) as measured by shoot extension, leaf size, and shoot dry weight. All paclobutrazol treatments (foliar and/or soil) increased root tip diameter and reduced unsuberized root length. Paclobutrazol increased the size of the cortex parenchyma cells and resulted in radial rather than longitudinal elongation of the innermost layer of cortex cells. These changes in cell shape and size were primarily responsible for increasing root tip diameter. Chemical name used: (R*,R*)-(±)-β-[(4-chlorophenyl)methy]-α-(l,l-dimethylethyl)-1H-1,2,4-triazole-l-ethanol (paclobutrazol).

Open Access

Cultivars of red (Acer rubrum L.) and Freeman maple (Acer ×freemanii E. Murray) are popular ornamental plants which are commonly placed in a variety of landscapes. To date, little information quantifies the capacity to tolerate and recover from drought among cultivars of red and Freeman maple. The objective of this study was to compare the effects of water stress on the physiology of five different maple cultivars of marketable size including four red maple genotypes, `Summer Red', `October Glory' (October Glory), `Autumn Flame', and `Franksred' (Red Sunset), as well as one hybridized Freeman maple genotype, `Jeffersred' (Autumn Blaze). Two-year-old cloned genotypes of red and Freeman maple were subjected to two treatments: irrigated daily to container capacity or irrigation withheld for one drought and recovery cycle. Light absorption, gas exchange, and chlorophyll fluorescence measurements were conducted under well-watered and drought stress conditions that approached 0.070 m3·m-3. Compared to well-watered conditions, drought stress conditions of 0.090 m3·m-3 had a significant main effect that reduced the amount of light absorption in four of the five genotypes. Additionally, absorption among genotypes was different under both well-watered and water stress conditions. Over the course of drought stress and a recovery phase, net photosynthesis and stomatal conductance were different among genotypes. Maximum photosystem II (PSII) efficiency of dark-adapted leaves (Fv/Fm) was lowered by the water stress condition. The efficiency of excitation capture by open PSII reaction centers (Fv`/Fm') was variable among genotypes. Photochemical quenching was higher in Autumn Blaze, October Glory, and `Summer Red' under drought conditions, which corresponded with a low degree of closure of PSII centers. Additionally, the fraction of excess excitation energy was also lower. Lastly, water deficit caused an increase in PSII efficiency in all genotypes except Autumn Blaze. This research demonstrated physiological variation among commercially available red and Freeman maple genotypes that may be selected for drought tolerance based on site moisture characteristics.

Free access

Abstract

Root growth is restricted in compact soil zones irrespective of whether the zones result from cultural equipment or are genetic in origin. Because yield may be reduced and production costs increased, proper diagnosis is important. To that end, penetrometer soil strength measurements were used in the field to characterize root-limiting soil-impedance characteristics for ‘Eldorado’ plums (Prunus salicina Lindl.). A penetrometer soil strength of 16 bars, measured at a volumetric water content of 16.9% (field capacity), was sufficient to lower root density to about 50% of that observed for low-strength soil. Tree growth (trunk circumference) was highly correlated with the averageprofile root density and the amount of silt present at a mid-profile depth. Low values of these parameters most probably were related to a water stress condition that reduced tree growth.

Open Access