; Schultheis et al., 2007 ; Strang et al., 2004 ), little has been done to determine the optimum spacing for mini triploid watermelon to obtain the highest percentages of marketable fruit (packout) in the 3- to 8-lb range. Increasing watermelon plant densities
Juan C. Rodriguez, Nicole L. Shaw, and Daniel J. Cantliffe
density ( Maynard and Scott, 1998 ; Nerson, 2002 ). Although higher plant populations may result in increased marketable yield per unit area ( Paris et al., 1985 ), the number of fruit per plant and fruit size are often reduced ( Kultur et al., 2001 ). In
Lexie McClymont, Ian Goodwin, Desmond Whitfield, Mark O’Connell, and Susanna Turpin
high tree density are widely seen as the way of the future for pear orchard design. Reported benefits include: improved fruit quality, controlling vegetative vigor, simplifying pruning and harvest, enabling the use of picking platforms (or robotics
Pedro Brás de Oliveira, Maria José Silva, Ricardo B. Ferreira, Cristina M. Oliveira, and António A. Monteiro
to manipulate light penetration is a routine management practice to raise and stabilize yields and also to improve fruit quality ( Oliveira et al., 1999 ). We recently showed that pruning date significantly reduces yield and that cane density has an
Orchard densities from 833 to 2500 trees/ha were studied on sod-podzolic soil (annual precipitation 550 mm). An orchard was planted in Spring 1990 and 1991 using 2-year-old nursery trees grown in film containers. The interval between trees in the row was 1 to 1.5 to 2 to 2.5 and 3 m. The trees were grafted on dwarf rootstock (62-396) and semi-dwarf (54-118). The commercial fruiting of `Tellisaare' began the third year after planting, `Antey' the fourth, and Spartan at fifth. The initial yield of `Antey in the most dense treatment was 14.5 t·ha–1, `Tellisaare' was 15 to 22 t·ha–1, according to rootstocks. Average yield of `Antey' on 62-396 for 1992–95 at the orchard density of 2500 trees/ha was 10 t·ha–1·year–1 and on rootstock of 54-118 it was 21 t·ha–1. However, yield of `Tellisaare' 54-118 for 1992–1995 was 13 to 15 t·ha–1 in all treatment of orchard density from 1666 to 833 trees/ha. The annual yield of this cultivar grafted on rootstock 54-118 at a tree density of 2500 plants/ha increased to 18.3 t·ha–1.
Mathieu Ngouajio, Erin C. Hill, and William Chase
Cucumber is an important vegetable in Michigan, where it is grown for slicing (fresh) or processing. Michigan is the top producer of pickling cucumbers in the United States, with over 27% of the total national production. Studies were conducted in 2004 to test the effects of plant density on cucumber fruit quality. Cucumber var. `Vlaspik' was seeded in 30.5, 45.7, 61.0, and 76.2 cm rows with 12.7 cm spacing between plants inside the row, corresponding to final plant populations of 258, 172, 129, and 103 thousand plants/ha, respectively. The experiment used a randomized complete-block design with 4 replications and four rows per plot. At harvest, 10 fruits of grade 2 were randomly selected from each plot for measurement of specific gravity, firmness, soluble solids, color, and seed size. Cucumber fruit specific gravity, soluble solids, and seed size were not affected by plant population size. However, fruit firmness and color varied with plant density. Low plant populations, when compared to high populations, produced darker green fruits, a desired trait in pickling cucumber production. On a scale of 0 (yellowish) to 5 (dark green), plants grown under a population of 258 thousand plants/ha scored an average of 2.8. The score was 4.6 for fruits produced in plots with 103 thousand plants/ha. Low plant populations increased fruit firmness as measured by a puncture test. Fruit firmness was 89, 93, 97, and 95 g·mm-2 for 258, 172, 129, and 103 thousand plants/ha, respectively. Results suggest that cultural practices may affect pickling cucumber fruit quality.
Stephen M. Southwick, Kitren G. Weis, James T. Yeager, and Hong Zhou
Whole-tree sprays of Release LC [predominantly gibberellic acid] (GA,) were applied in a commercial peach [Prunus perisca (L.) Batsch.] orchard in the California Central Valley on three dates from mid-June (about 90 days after full bloom = 28 days before harvest) to late July (14 days postharvest) 1993 at 50, 75, 100, and 120 mg·liter-1. Gibberellin (GA) reduced the number of flowers differentiated in 1993, thereby reducing fruit density in 1994, when sprays were applied by early July 1993. Sprays in late July did not reduce flowering and fruiting density in the following year. In 1994, there were fewer fruit located on the proximal third of the shoot after GA sprays of 75,100, and 120 mg-liter' applied on 15 June compared to hand-thinned controls, and reduction was linear with increase in GA rate. Fruit numbers in the middle and distal sections of shoots were reduced by all 15 June and some 9 July GA sprays, with fewer fruit as concentration increased. However, the distribution of fruit within shoot sections, after GA treatments during floral differentiation, expressed as a percentage of the total number of fruit along fruiting shoots, showed even fruiting compared with hand thinning. Due to reduced flowering in response to GA treatments in June and early July 1993, the hand-thinning requirement was significantly reduced, with no thinning required in 1994 from 15 June 1993 GA sprays. All sprays applied in early July resulted in 40% to 60% fewer fruit removed during thinning than the nontreated controls. Sprays in late July were ineffective. Sprays of GA applied in mid-June at 50,75, 100, and 120 mg·liter and sprays of 120 mg·liter-1 GA applied in early July (4 days preharvest) increased the firmness of `Loadel' cling peach (about 26% improvement in June sprays) in 1993. The salable yield of fruit (after removal of the undersized fruit) was the same on hand thinned and on non-hand thinned trees treated with GA on 15 June at 50 mg·liter-1. The salable yield of fruit was increased by GA sprays of 50 and 75 mg·liter applied on 9 July 1993 compared to controls. There were no differences in fruit size (by weight or diameter) among the aforementioned treatments and hand thinning. GA sprays of 75,100, and 120 mg-liter' applied on 15 June 1993 tended to reduce salable yield, but fruit size increased with decreased yield. Based on the results obtained in 1993 and 1994, we believe that Release LC has good potential for chemically thinning peaches in California.
B.E. Maust, J.G. Williamson, and R.L. Darnell
Floral budbreak and fruit set in many southern highbush blueberry (SHB) cultivars (hybrids of Vaccinium corymbosum L. with other species of Vaccinium) begin prior to vegetative budbreak. Experiments were conducted with two SHB cultivars, `Misty' and `Sharpblue', to test the hypothesis that initial flower bud density (flower buds/m cane length) affects vegetative budbreak and shoot development, which in turn affect fruit development. Flower bud density of field-grown plants was adjusted in two nonconsecutive years by removing none, one-third, or two-thirds of the flower buds during dormancy. Vegetative budbreak, new shoot dry weight, leaf area, and leaf area: fruit ratios decreased with increasing flower bud density in both cultivars. Average fruit fresh weight and fruit soluble solids decreased in both cultivars, and fruit ripening was delayed in `Misty' as leaf area: fruit ratios decreased. This study indicates that because of the inverse relationship between flower bud density and canopy establishment, decreasing the density of flower buds in SHB will increase fruit size and quality and hasten ripening.
Justine E. Vanden Heuvel, John T.A. Proctor, and J. Alan Sullivan
This research was supported by the Ontario Ministry of Agriculture, Food, and Rural Affairs, and the Ontario Fruit and Vegetable Growers Association. We thank B. Trenwith of Stonehaven Farms for the use of his plant material. This paper is a portion
Jack Jordan, E.J. Gregory, D. Smith, and I. Benally
A three density-three rootstock test was conducted on three spur-type apple cultivars grown in sandy loam soil. Trees of the three cultivars: `Redspuree' (RS), `Goldspuree' (GS), and `Spuree Rome' (SR) were trained to a central leader system in a 100% grass cover. All cultivars produced best in the high density planting (1344 trees/ha.). Most consistently and significantly affected were the SR. The least productive density, the low density, had 336 trees per ha. while the medium density had 672 trees/ha. Density had a more significant effect on SR culls and a slightly more significant effect on SR fruit soluble solids than it did on these variables of the other cultivars. Density had little effect on fruit firmness of all cultivars. Of these rootstocks: m7a, m26, and mml06, the mml06 rootstock usually produced the greatest yields, especially in the RS and SR cultivars. Results for the GS were more variable than they were for RS and SR with its production on the m7a rootstock occasionally exceeding that of the mml06 rootstock. The m26 rootstock produced the lowest yields. Rootstock had no significant effect on fruit firmness of all cultivars.