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Deron Caplan, Mike Dixon, and Youbin Zheng

( Muntendam et al., 2012 ). These acids decarboxylate during storage ( Ross and ElSohly, 1997 ; Taschwer and Schmid, 2015 ) and upon heating ( Kimura and Okamoto, 1970 ) to become neutral cannabinoids, such as THC and CBD. The inflorescence dry weight and

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Panayiotis A. Nektarios, Serafim Kastritsis, Nikolaos Ntoulas, and Panayiota Tsiotsiopoulou

et al., 2003b ) as well as shoot, leaf, and root dry weight ( Tsiotsiopoulou et al., 2003 ). Chan and Joyce (2007) found increased plant height and stem diameter but minimal improvement on leaflet numbers of Flindersia schottiana saplings after

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Luis A. Valdez-Aguilar, Catherine M. Grieve, and James Poss

‘Flagstaff’ included: plant height, and number, length and diameter of flowering shoots, diameter of the terminal flower on each stem, and leaf, flower, and shoot dry weight (DW). Plant height was measured from the base at the plant to the top of the terminal

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Juanita Popenoe

`Heritage', `Titan', and `Boyne' red raspberries (Rubus idaeus L.) were grown for 3 years and plots were sampled annually for changes in growth. `Heritage' is a primocane- and floricane-fruiting, strongly suckering cultivar; `Boyne' is a floricane-fruiting, strongly suckering cultivar; and `Titan' is a floricane-fruiting, weakly suckering cultivar. Each year in October, plants of each cultivar were dug from two 0.5-m2 plots in each of four rows, separated into roots, crowns, canes (primocanes were harvested in October and floricanes were harvested in July), and leaves, and dried. Fruit were harvested, yields were recorded, and dry weights of subsamples were used to estimate total fruit dry weights. `Heritage' fruit included the primocane and floricane harvests. `Heritage' was more yield-efficient than `Boyne' or `Titan' in that it allocated a higher percentage of total dry weight to fruit and a lower percentage to vegetative parts. Although `Titan' had fewer canes, cane diameter and length were greater. `Boyne' allocated higher percentages of total dry weight to roots than other cultivars. The percentage of total dry weight allocated to fruit was similar for `Boyne' and `Titan' in 1992, but lower for `Boyne' in 1991. Within the cultivars tested, phenotype for suckering did not indicate productivity.

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Ido Schechter, J.T.A. Proctor, and D.C. Elfving

Mature apple trees (Malus domestica Borkh.) were studied in the 1989 and 1990 seasons to explore the effect of differential crop load on fruit dry weight (DW), DW content, specific leaf weight, and leaf carbon exchange, using girdled and non-girdled limbs. Fruit DW and DW content decreased with heavier fruit loads, however, fruit on girdled limbs had higher fruit DW and DW content. Specific leaf weight did not differ in leaves on non-girdled limbs along the crop load gradient, but increased dramatically in leaves on girdled limbs with crop load lighter than one fruit per cm2 cross-sectional area. These leaves also had a low photosynthetic rate, high stomatal resistance, and high internal CO2 concentration. The results suggest a physiological limit for photoassimilate usage by the tree. Exceeding this limit by reducing sink strength resulted in excessive carbohydrate accumulation in leaves, causing physical damage to the photosystem.

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D. Bradley Rowe, Stuart L. Warren, and Frank A. Blazich

Catawba rhododendron (Rhododendron catawbiense Michx.) seedlings of two provenances, Johnston County, N.C. (35°45′N, 78°12′W, elevation = 67 m), and Yancey County, N.C. (35°45′N, 82°16′W, elevation = 1954 m), were grown in controlled-environment chambers for 18 weeks with days at 18, 22, 26, or 30C in factorial combination with nights at 14, 18, 22, or 26C. Shoot and root dry weights and total leaf areas of seedlings of the Yancey County provenance (high elevation) exceeded (P ≤ 0.05) those of the Johnston County (low elevation) provenance at all temperature combinations. Leaf area was maximal at 22/22C, 18/26C, and 22/26C and minimal at 30/14C (day/night). Shoot dry weight responded similarly. Root dry weight decreased linearly with increasing day temperature, but showed a quadratic response to night temperature. Leaf weight ratio (leaf dry weight: total plant dry weight) increased, while root weight ratio (root dry weight: total plant dry weight) decreased with increasing day temperature. Leaf weight ratio was consistently higher than either stem or root weight ratios. Day/night cycles of 22 to 26/22C appear optimal for seedling growth.

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Laura J. Lehman, Eric Young, and C.R. Unrath

Spur-type or nonspur `Delicious' apple scions on either Malus domestica Borkh. (seedling) or M.26 rootstocks received paclobutrazol foliar sprays in one or two `consecutive years or a soil drench in the year of planting. For each scion, total shoot, root shank, and tree dry weights measured in the 3rd year after planting were suppressed by all treatments. Trees on M.26 put less dry weight into rootstock wood after foliar sprays, but trees on seedling were not similarly affected. No treatment influenced fibrous root dry weight of the spur-type scion on seedling, while all treatments suppressed dry-weight gain of the same scion on M.26. All trees had higher root: shoot ratios and blossom densities 3 years after the soil drench and several had higher ratios after foliar sprays. Chemical name used: ß-[(4-chlorophenyl)methyl] (l,l-dimethylethyl)-l-H-1,2,4-triazole-l-ethanol (paclobutrazol, PB).

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Mary Ann Rose and Barbara Biernacka

Seasonal patterns of N, P, and K accumulation and remobilization in Freeman maple (Acer× freemanii E. Murr. `Jeffersred') were studied to guide future improvements in fertilization efficiency. Leaves, stems, and roots of container-grown trees were harvested over a 12-month period (June to June) in each of two experiments. Plants were fertilized from June to October with three rates of soluble fertilizer (50, 100, and 200 mg·L-1 N). Fertilizer rate had linear and quadratic effects on dry weight and nutrient contents, but did not affect seasonal accumulation patterns. Whole-plant nutrient contents and dry weights increased until mid-October, prior to leaf abscission. The largest fractions of nutrients and dry weight were allocated to leaves until early September. Between September and October, the most rapid accumulation of N, P, and dry weight occurred in root tissue. Highest nitrogen recovery efficiency occurred in late summer (Expt. 2) or early fall (Expt. 1). There was no statistically significant evidence for N, P, or K resorption in the fall, but evidence of N (not of P or K) remobilization in the spring was very strong. Whole plant dry weight doubled between April and June, while ≈50% of the N stored in woody tissues was translocated to new shoots.

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Arthur D. Wall and Joe N. Corgan

In dry climates, onions usually have the roots undercut at maturity before harvest. In a 2-year study, dehydrator onions were uprooted at maturity to simulate undercutting, and harvest was delayed for several time intervals. Treatment effects on fresh and dry yield, the number of bulbs per plot, bulb fresh and dry weights, and percent dry weight of bulbs were measured. Plots were considered mature when 80% of the tops had fallen. Delaying harvest 15 days after maturity without uprooting did not reduce yield significantly. Yield and both bulb weight and percent dry weight tended to decline when harvest was delayed >15 days after maturity, especially if plants were uprooted. This suggests that undercutting of onions should not be performed until just prior to harvest and that harvest should not be delayed >15 days past maturity. Yield losses in delayed harvest treatments were attributed primarily to Fusarium basal rot.

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T. L. Robinson, W. C Stiles, and A. N. Lakso

In two field studies with `Redchief Delicious'/MM.106, 'Empire'/M.9/MM.106 and 'Mutsu'/M.9/MM. 106 trees on fertile silt loam soils, trickle irrigation increased vegetative growth during the first three years and resulted in a 16%-20% increase in cumulative yield over the first five years. When fertilizer was injected into the irrigation water weekly from mid-April until the end of June, tree growth was further increased and cumulative yield was improved an additional 11%-15% for a total of 27%-35% greater yield than the non-irrigated trees. In these studies, ground fertilization did not improve growth or yield unless trickle irrigation was also applied. However, ground fertilization was not as effective as fertigation.

Irrigation and fertigation increased the dry weight of roots by 23% and that of shoots by 36% in the first year resulting in a 10% reduction in the root/shoot ratio. Total tree dry weight was increased by 30% if trees were planted early (April 14) but only 14% if trees were planted late (June 10).

Early planting resulted in 17% greater cumulative yield than trees planted late. Initial tree caliper also had a significant effect on early growth and yield with large caliper trees yielding 12% more than the small caliper trees. The interaction of planting date, tree caliper and fertigation resulted in a 50%-70% increase in yield during the first five years.