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Upright Fruiting Offshoots (UFO) is a novel high-density training system for sweet cherry (Primus avium L.) that produces fruit on multiple vertical leaders ("offshoots") arising from a cordon-like trunk. The promotion of sufficient upright shoot number and uniform shoot distribution during establishment are key to development of this training system. Trunk angle, meristem management (selective bud retention and removal), and cordon height at establishment were evaluated for influence on shoot number, shoot distribution, total shoot length, and early fruiting potential. At planting, trunk angles of 45° or 60° from the horizontal resulted in increased shoot growth compared with 30°, and also increased shoot distribution when bud selection was not imposed. A cordon height of 45 cm increased total shoot length by 20% compared with a 60-cm cordon height. Bud selection (retaining buds for optimal upright shoot distribution and removing all others) improved canopy development by reducing the number of shoots in the terminal third of the cordon and increasing the number of shoots in the basal and middle thirds compared with no bud selection. Bud selection reduced fruiting potential in the 2nd and 3rd years compared with unmanaged treatments, but subsequently surpassed those treatments in projected annual yield in Year 4 and cumulative yield in Year 5. Bud selection increased total and average shoot length, and improved distribution while moderating early crop load potential. Planting angle, cordon height, and bud selection significantly impact canopy establishment of UFO trees by affecting shoot number, length, and distribution. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of light availability and the climatic conditions on the growth and quality of weeping fig (Ficus benjamina L.). Plants of cv. Danielle were grown under five shading conditions (0%, 20%, 40%, 60%, and 80% reduction of the incident irradiance inside the greenhouse) and two cultivation periods (from May to October and from December to May). The light intensity in no shading treatment ranged from 6.3 to 16.4 MJ⋅m-2⋅d-1 in May to October and from 4.6 to 14.5 MJ⋅m-2⋅d-1 in December to May. Depending on climatic conditions, the light reduction resulting from shading produced strong differences in the growth of weeping fig. With increasing shading, the dry weight decreased from 282.4 to 113.3 g/plant during the first growth period, which was the period characterized by the highest values of global radiation and temperature, and from 120.8 to 56.8 g/plant during the second period. The effects of reduced light were evident in the plant quality, which is associated with the canopy and leaf characteristics. In particular, as a result of the increase of the apparent quantum yield and reduction of light compensation point, the most shaded plants showed a photosynthetic advantage over the control (0%) at a low irradiance level. Increased shading caused a reduction of plant compactness because of the increase of the internode length and branch insertion angle. Although shading also resulted in a reduction in the leaf number, the plant ornamental value was unaffected because of the highest unit leaf area (+72%) in both of the growth periods. Based on our results, the greatest decrease in irradiance (60% and 80% of shading) reduced the plant growth and compactness more in the growth period characterized by the highest values of global radiation and temperature, whereas the quality of the plants was improved by shading in both of the growth periods. [ABSTRACT FROM AUTHOR]

Research in dent corn has found significant variation in crop/weed competition for light among hybrids. However, little has been published on the extent of variation in sweet corn competitive ability. Field studies were conducted under weed-free conditions to quantify canopy development and light environment among three sweet corn hybrids and to determine associations among canopy characteristics to crop yield. An early-season hybrid (Spirit) and two midseason hybrids (WHT2801 and GH2547) were grown at experimental sites located near Urbana, Ill., and Prosser, Wash., in 2004 and 2005. Maximum leaf area index (LAI) and intercepted photosynthetically active radiation (PAR) was typically highest for GH2547 and lowest for Spirit. Most differences in vertical LA! among hybrids was observed above 60 and 150 cm in Illinois and Washington, respectively, with WHT2801 and GH2547 having leaf area distributed higher in the canopy than Spirit. Both number and mass of marketable ears were positively correlated with maximum relative growth rate (correlation coefficients 0.60-0.81), leaf area duration (0.68-0.79), total LA! (0.56-0.74) at R1, and intercepted PAR (0.74-0.83) at RI. Differences in canopy properties and interception of solar radiation among Spirit, WHT2801, and GH2547 lead us to hypothesize that variation in weed-suppressive ability exists among hybrids. Future testing of this hypothesis will provide knowledge of interactions specific to sweet corn useful for developing improved weed management systems. [ABSTRACT FROM AUTHOR]

Traditional sweet cherry (Prunus avium L.) training systems in the United States are based upon vigorous rootstocks and multiple leader vase canopy architectures. The sweet cherry research lab at Washington State University has been investigating the potential of new rootstocks and training systems to improve production efficiency and produce high quality fruit. This paper describes the effects of three rootstocks--Mazzard (P. avium), 'Gisela 6', and 'Gisela 5' (P. cerasus x P. canescens)--and four training systems--central leader, multiple-leader bush, palmette, and y-trellis--on 'Bing' sweet cherry tree vigor, fruit yield and quality over a seven year period. Compared to trees on Mazzard, trees on 'Gisela 5' and 'Gisela 6' had 45% and 20% lower trunk cross-sectional areas after 7 seasons, respectively. Trees on 'Gisela 6' were the most productive, yielding between 13% and 31% more than those on 'Gisela 5' and 657% to 212% more than trees on Mazzard, depending on year. Both Gisela rootstocks significantly improved precocity compared to Mazzard, bearing fruit in year 3 in the orchard. Canopy architecture had only moderate effects on tree vigor and fruit yield. Across rootstocks, bush-trained trees were about 25% less productive compared to the other systems, which exhibited similar cumulative yields (102 kg/tree). Fruit weight was negatively and closely (r² = 0.84) related to tree yield efficiency (kg·cm-2). Crop value was related positively to fruit yield. [ABSTRACT FROM AUTHOR]

Fruit set is a key component of essential oil yield from fennel (Foeniculum vulgare Mill.) under Tasmanian conditions. Fruit set in commercial crops is often low, possibly due to incomplete pollination. Fennel flowers are strongly protandrous and a series of flowers must be produced to ensure pollination. The hypothesis tested was that decreasing stand density increases the number of lateral branches, thereby increasing the number of higher order umbels and thus increasing the overlap between the periods of pollen production and stigma receptivity. A field trial was used to examine the number of umbels of each order produced under stand densities of 4, 12, 25, 50 and 100 plants/m². Stand density influenced the ratio of pollen producing to pollen receptive umbels and stand densities of 50 and 100 plants/m² showed a distinct imbalance between pollen production and stigma receptivity. The data collected supported the hypothesis and it is probable that, in commercial crops, fruit set is being reduced by a lack of synchrony between pollen production and stigma receptivity. The highest stand density tested reduced total oil production. We therefore recommend the inclusion of low stand-density strips within standard-density commercial crops. [ABSTRACT FROM AUTHOR]