similar to previous studies ( Holeček, 2002 ; Kimball and Jefferson, 2001 , 2006 ; Pasiakos et al., 2011 ). The objectives of this study were to investigate the use of BCAA for increasing the shoot density of creeping bentgrass and determine whether
Isaac T. Mertz, Nick E. Christians and Adam W. Thoms
Joaquin A. Chong, Uttara C. Samarakoon and James E. Faust
, 1991 ; Clifford et al., 2004 ), bract size, and flowering dates ( Liu and Heins, 2002 ). These studies typically describe the growth and development of the dominant shoots in a canopy with a relatively low canopy density (shoots/m 2 ), i.e., low
A.G. Reynolds, C.G. Edwards, D.A. Wardle, D.R. Webster and M. Dever
`Riesling' grapevines (Vitis vinifera L.) were subjected for 4 years (1987-90) to three shoot densities (16, 26, and 36 shoots/m of row) combined with three crop-thinning levels (1, 1.5, and 2 clusters/shoot) in a factorialized treatment arrangement. Weight of cane prunings per vine (vine size) decreased linearly with increasing shoot density and clusters per shoot. Cane periderm formation (in terms of percent canes per vine with >10 ripened internodes) was inhibited by increased shoot density, while vine winter injury (primarily bud and cordon) increased slightly in a linear fashion with increasing clusters per shoot. Canopy density and leaf area data suggested that fruit clusters were most exposed to sunlight at a shoot density of 26 shoots/m of row due to reduced lateral shoot growth and a trend toward slightly smaller leaves. Yield, clusters per vine, and crop load (yield per kilogram of cane prunings) increased with increasing shoot density and clusters per shoot, while other yield components (cluster weight, berries per cluster, and berry weight) decreased. Soluble solids and pH of berries and juices decreased with increasing shoot density and clusters per shoot, but titratable acidity was not substantially affected. Free volatile terpenes increased in berries and juices in 1989 with increasing shoot density, as did potentially volatile terpenes in 1990. Shoot densities of 16 to 26 shoots/m of row are recommended for low to moderately vigorous `Riesling' vines to achieve economically acceptable yields and high winegrape quality simultaneously.
Patricia Sweeney, Karl Danneberger, Daijun Wang and Michael McBride
Limited information is available on the performance under temperate conditions in the United States of recently released cultivars of creeping bentgrass (Agrostis stolonifera L.) with high shoot density for use on golf course putting greens. Fifteen cultivars were established in Aug. 1996 on a greens mix with high sand content to compare their seasonal weights and total nonstructural carbohydrate (TNC) contents. The cultivars were maintained at 3.1 mm height of cut. Shoot density counts were taken during Apr., July, and Oct. 1998. Root weights and nonstructural carbohydrate levels were assessed monthly from June 1997 through Nov. 1998. A cultivar group contrast between the high shoot density cultivars (`Penn A1', `Penn A2', `Penn A4', `Penn G1', `Penn G2', and `Penn G6') and the standard cultivars (`Penncross', `Crenshaw', `Southshore', `DF-1', `Procup', `Lopez', `SR1020', and `Providence') revealed that the former averaged 342.9 and 216.1 more shoots/dm2 on two of the three sampling dates. Root dry weights did not vary significantly (P ≤ 0.05) among the cultivars. Performing a contrast between new high shoot density cultivars and standard cultivars revealed greater root dry weight in the former during Mar. and May 1998. Differences (P ≤ 0.05) in TNC were observed on two of the 18 sampling dates, but no trends were evident.
Richard P. Marini and Donald L. Sowers
The relationship between peach [Prunus persica (L.) Batsch] fruit position and fruit weight (FW) was studied in experiments involving thinned vs. nonthinned fruiting shoots, shoots with and without axillary shoots, and trees with varying crop densities (CDs). FW was not consistently related to position on the shoot, and the influence of fruit position varied depending on the presence of axillary shoots on the fruiting shoot. FW was best related to fruiting shoot length and total shoot length per fruit (1-year-old plus current-season wood). Mean FW was also influenced by the number of fruit per shoot × CD interaction, a result indicating that FW depends on photosynthate from leaves in the immediate vicinity of the fruit as well as photosynthate from more distant parts of the tree.
A.G. Reynolds, C.G. Edwards, D.A. Wardle, D. Webster and M. Dever
`Riesling' grapevines (Vitis vinifera L.) were subjected for 4 seasons (1987-90) to three shoot densities (16, 26, and 36 shoots/m of row) combined with three crop-thinning levels (1, 1.5, and 2 clusters per shoot) in a factorial design. Wines were made from all treatment combinations in 1989. Aroma compounds such as trans-3-hexen-1-ol, linalool, and linalool oxides 1 and 2 in many cases decreased in nonaged and aged wines by increasing shoot density and clusters per shoot, while cis-3-hexen-1-ol increased. Aging wines increased concentrations of cis-3-hexen-1-ol, citronellol, α-terpineol, and the linalool oxides, while linalool decreased. Tasters identified aged wines from the lowest shoot densities and clusters per shoot as having the most ripe-fruit flavor and the least green-fruit flavor and perceived acidity. Flavor descriptors were correlated with linalool, cis-3-hexen-1-ol, and linalool oxide 1. Shoot densities of 20 to 25 shoots/m of row are recommended for low to moderately vigorous `Riesling' vines to achieve economically acceptable yields and high wine quality simultaneously.
J.G. Williamson, D.C. Coston and J.A. Cornell
Planting treatments were evaluated for their influence on shoot development and root distribution of own-rooted `Redhaven' peach [Prunus persica (L.) Batsch] trees planted to high density (5000 trees/ha). Planting in fabric-lined trenches (FLT) or narrow herbicide strips (NHS) reduced the diameter and length of primary shoots, the number and combined length of second-order shoots, and the total length of shoots. Flower density, the number of flowers per node, and the percentage of nodes containing one or more flowers were increased for FLT trees but not for NHS trees when compared with controls. The length of primary shoots increased quadratically for all treatments with increasing limb cross-sectional area (LCA). The total length of shoots increased more with increasing LCA for controls than for FLT trees. The number of flowers per shoot increased linearly for all treatments with increasing LCA values. Root concentration decreased with increasing soil depth and distance from tree rows for all treatments. Reduced widths of weed-free herbicide strips had little effect on root distribution. Roots of FLT trees were reduced in number and restricted vertically and laterally when compared with other planting treatments. The FLT treatment modified shoot development by reducing the length of total shoots and length of primary shoots across LCA values measured when compared with NHS and control-treatments.
Elio Jovicich, Daniel J. Cantliffe and George J. Hochmuth
In greenhouse crops, fruit yield and quality can be increased by managing shoot pruning and plant density. The effect of plant population density (2, 3, and 4 plants/m2 as function of in-row plant spacings of 66.5, 44.3, and 33.3 cm, respectively), and shoot pruning (one, two, and four main stems) was studied for effects on fruit yield, quality and plant growth of greenhouse-grown sweet pepper (Capsicum annuum L. cv. Robusta) during Summer 1998 in Gainesville, Fla. Red fruit were harvested 84 and 118 days after transplanting (14 Apr.). Additional fruit set was inhibited due to the high temperatures. Marketable yield (number and weight) per square meter increased linearly with plant density and was greater on plants with four stems than in those with two or one stem. Extra-large fruit yield per square meter was not affected by plant density, but was higher in four-stem plants. Total marketable yield and extra-large fruit yields per plant were greatest in the four-stem plants at two plants per square meter. The stem length and the number of nodes per stem increased linearly with the decrease in plant spacing. Stem length and number of nodes per stem were greater in single-stem than in four-stem plants. Number and dry weight of leaves, stem diameter, and total plant dry weight were higher in four- and two-stem plants than in single-stem plants. Results indicated that four plants per square meter pruned to four stems increased marketable and extra-large fruit yield in a short harvest period of a summer greenhouse sweet pepper crop in north central Florida.
Haijun Zhu and Eric T. Stafne
Due to the strong vegetative nature of relatively young pecan trees and the absence of dwarfing rootstocks or cultivars, controlling tree size is a major problem in high-density pecan orchards. Paclobutrazol, an effective inhibitor of gibberellin
E.H. Ervin, C.H. Ok, B.S. Fresenburg and J.H. Dunn
'Meyer' zoysiagrass (Zoysia japonica Steud.) is a popular turfgrass species for transition zone golf course fairways and tees because it is generally winter hardy while providing an excellent playing surface with minimal chemical and irrigation inputs. However, its functionality declines readily on many of the shaded areas on these courses. Reduced irradiance causes excessive shoot elongation, reduced tillering, and weak plants that are poorly suited to tolerate or recover from traffic and divoting. Trinexapac-ethyl (TE) effectively reduces gibberellic acid (GA) biosynthesis and subsequent shoot cell elongation. The objective of this study was to determine if monthly applications of TE would reduce shoot elongation of 'Meyer' zoysiagrass and improve stand persistence under two levels of shade. Shade structures were constructed in the field that continuously restricted 77% and 89% irradiance. A mature stand of 'Meyer' was treated with all combinations of three levels of shade (0%, 77%, and 89%) and three levels of monthly TE application [0, 48 g·ha-1 a.i. (0.5×), and 96 g·ha-1 a.i. (1×)] in 1998 and 1999. In full sun, the 0.5×-rate reduced clipping production by 17% to 20% over a four-week period and the 1×-rate by 30% to 37%. Monthly application of TE at the 1×-rate increased 'Meyer' tiller density in full sun and under 77% shade. Both rates of TE consistently reduced shoot growth under shade relative to the shaded control. Only the monthly applications at the 1×-rate consistently delayed loss of quality under 77% shade. The zoysiagrass persisted very poorly under 89% shade whether treated or not with TE and plots were mostly dead at the end of the experiment. Our results indicate TE can be an effective management practice to increase 'Meyer' zoysiagrass persistence in shaded environments. Chemical name used: 4-cyclopropyl-α-hydroxy-methylene-3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl)