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S. Kaan Kurtural, Lydia F. Wessner and Geoffrey Dervishian

at harvest, and production efficiency of a procumbent cultivar in a warm climate region. Materials and Methods Vineyard description and experimental layout This study was conducted from 2009 to 2011 at a commercial vineyard planted with ‘Syrah

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Terence L. Robinson, Alan N. Lakso and Zhongbo Ren

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Terence L. Robinson and Alan N. Lakso

Bases of orchard productivity were evaluated in four 10-year-old apple orchard systems (`Empire' and `Redchief Delicious' Malus domestics Borkh. on slender spindle/M.9, Y-trellis/M.26, central leader/M.9/MM.111, and central leader/M.7a). Trunk cross-sectional areas (TCA), canopy dimension and volume, and light interception were measured. Canopy dimension and canopy volume were found to be relatively poor estimators of orchard light interception or yield, especially for the restricted canopy of the Y-trellis. TCA was correlated to both percentage of photosynthetically active radiation (PAR) intercepted and yields. Total light interception during the 7th to the 10th years showed the best correlation with yields of the different systems and explained most of the yield variations among systems. Average light interception was highest with the Y-trellis/M.26 system of both cultivars and approached 70% of available PAR with `Empire'. The higher light interception of this system was the result of canopy architecture that allowed the tree canopy to grow over the tractor alleys. The central leader/M.7a had the lowest light interception with both cultivars. The efficiency of converting light energy into fruit (conversion efficiency = fruit yield/light intercepted) was significantly higher for the Y-trellis/M.26 system than for the slender spindle/M.9 or central leader/M.9/MM.111 systems. The central leader/M.7a system bad the lowest conversion efficiency. An index of partitioning was calculated as the kilograms of fruit per square centimeter increase in TCA. The slender spindle/M.9 system had significantly higher partitioning index than the Y-trellis/M.26 or central leader/M.9/MM.111. The central leader/M.7a system had the lowest partitioning index. The higher conversion efficiency of the Y/M.26 system was not due to increased partitioning to the fruit; however, the basis for the greater efficiency is unknown. The poor conversion efficiency of the central leader/M.7a was mostly due to low partitioning to the fruit. The Y-trellis/M.26 system was found to be the most efficient in both intercepting PAR and converting that energy into fruit.

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K. Rachelle Goldman and Cary A. Mitchell

The day-neutral, semidwarf rice (Oryza sativa L.) cultivar Ai-Nan-Tsao was grown in a greenhouse under summer conditions using high-pressure sodium lamps to extend the natural photoperiod. After allowing 2 weeks for germination, stand establishment, and thinning to a consistent planting density of 212 plants/m2, stands were maintained under continuous lighting for 35 or 49 days before shifting to 8- or 12-h photoperiods until harvest 76 days after planting. Non-shifted control treatments consisting of 8-, 12-, or 24-h photoperiods also were maintained throughout production. Tiller number increased as duration of exposure to continuous light increased before shifting to shorter photoperiods. However, shoot harvest index and yield efficiency rate were lower for all plants receiving continuous light than for those under the 8- or 12-h photoperiods. Stands receiving 12-h photoperiods throughout production had the highest grain yield per plant and equaled the 8-h-photoperiod control plants for the lowest tiller number per plant. As long as stands were exposed to continuous light, tiller formation continued. Shifting to shorter photoperiods late in the cropping cycle resulted in newly formed tillers that were either sterile or unable to mature grain before harvest. Late-forming tillers also suppressed yield of grain in early-forming tillers, presumably by competing for photosynthate or for remobilized assimilate during senescence. Stands receiving 12-h photoperiods throughout production not only produced the highest grain yield at harvest but had the highest shoot harvest index, which is important for resource-recovery strategies in advanced life-support systems proposed for space.

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Michael P. Harvey and Mark H. Brand

Hakonechloa macra Makino 'Aureola' is an ornamental, shade tolerant landscape grass that grows slowly and commands high prices. Hakonechloa plants grown from four initial division sizes, of 1-2, 4-6, 8-10, or 12-15 tiller buds, were evaluated following a complete growing season (105 days). Based on visual observation, we rated 100% of plants grown from the two larger division sizes to be salable compared with only 30% of those from divisions containing 4-6 growing points, and none from the smallest division size. However, divisions of 1-2 tiller buds produced twice as many new shoots and tiller buds per initial tiller bud as did larger division sizes. To produce salable plants in one growing season, results suggest the use of 8-10 tiller bud divisions, but for propagation and increase of stock material, where it is important to obtain the greatest number of new growing points per initial growing point, use of the smaller division sizes is indicated. Hakonechloa plants were grown under shading densities of 0%, 30%, 50%, or 70% provided by polypropylene shade cloth. Shading increased overall growth and improved the appearance and leaf color of Hakonechloa, but at 70% shade density, plants appeared languid and open. For this reason, 50% shading is recommended for nursery production of Hakonechloa macra 'Aureola'.

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Edward F. Durner and Joseph C. Goffreda

Three peach [Prunus persica (L.) Batsch] rootstock plantings were monitored for date and rate of bloom during Spring 1989 and 1990 to determine if the time of scion bloom on different rootstocks is determined by the date of initiation of bud growth in the spring or by the duration of a particular bud stage. Included were a 1984 planting of `Redhaven' on eight rootstocks, a 1984 planting of `Rio-Oso-Gem' and `Loring', each on 11 rootstocks, and a 1986 planting of `Encore' on 18 rootstocks. The effect of rootstock on bud phenology was consistent within scion cultivar over two extremely different spring temperature profiles. In `Redhaven' and `Rio-Oso-Gem', rootstocks affected the dates but not the rates of bud development. Rootstocks affected both the dates and rates of `Loring' and `Encore' bud development. No consistent effect of rootstock on yield could be associated with delayed bud development in `Rio-Oso-Gem', `Redhaven', or `Loring'; however, delayed bud development of `Encore' on `Okinawa' x `Cardinal' and 62325 resulted in enhanced yield following spring frosts.

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T. Auxt Baugher, H.W. Hogmire, A.R. Biggs, S.I. Walter, D.W. Leach, T. Winfield and G.W. Lightner

Apple packout audits were conducted during 1991 to 1993 to assess effects of five orchard systems (three cultivars, two age groups) on fruit packout and determine if relationships exist between light quality and productivity. Cultivar/rootstock combinations on 1979 T-trellis and central-leader systems had the lowest light levels and relative yields. Trees on either 1979 3-wire trellis, 1986 MIA, or 1985 West Virginia spindle had the highest light transmission, and trees on 1979 or 1985 West Virginia spindle systems had the highest yields. Extra fancy/fancy packouts across systems ranged from 40% to 85%. `Empire', regardless of system, had the highest packouts, and `Golden Delicious' on 1979 or 1986 central leader had the lowest packouts. A regression analysis comparing percentage packout in grades below fancy to percentage full sun indicated that reduced packouts were related to low light conditions. Orchard system influenced the number of fruit downgraded due to color, russet, bruises, bitter pit, cork spot, apple scab, rots, sooty blotch/fly speck, and tufted apple budmoth. Regression analyses comparing defects to field data indicated that bitter pit decreased as yield efficiency increased, and rot and sooty blotch/fly speck incidence were related to low canopy light penetration. Revenue losses were disproportionate to percentage of downgraded fruit because some defects had a greater impact on grade than others. The greatest revenue losses were for russet in `Golden Delicious' on 1986 central leader ($1656.60/acre) and for bitter pit in `Golden Delicious' on 1979 T-trellis ($1067.30/acre). Total losses in returns for individual systems ranged from $453.71/acre for `Empire' on 3-wire trellis to $3145.49/acre for `Golden Delicious' on 1986 central leader. The comparisons of young versus mature system yields and packouts indicate that medium- to high-density vertical or inclined canopy systems are superior to horizontal or low-density vertical freestanding systems. The cost-benefit analyses prescribe areas where management can be changed in existing systems to increase profitability.

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W.B. Evans, V. Cerven, N. Winter and C.E. Coker

This report presents preliminary data and arguments supporting the investigation and possible adoption of a low-cost method of cherry and grape tomato (Solanum lycopersicum) production. Cherry and grape tomato crops are currently grown using indeterminate or relatively large determinate plants requiring trellising and significant hand labor at harvest. In contrast, processing tomato crops are usually determinate cultivars raised without supporting systems, and they are harvested mechanically. In Summer 2009, a Mississippi trial of home garden tomato cultivars included a compact, mounding yellow-fruited cherry tomato that produced more than 2 kg of fruit per plant in the first harvest. The architecture of the plant, high yield potential, and concentrated set indicate that there is potential to grow commercial cherry and grape tomato crops in much the same way commercial processing tomatoes are grown: unsupported on bare or mulched beds, with once-over harvest. Such a system could reduce the monetary and labor costs of production of cherry and grape tomatoes. Seed companies, tomato growers, and supporting agencies should work together to further investigate the potential of this system of cherry and grape tomato production.

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Changying Li, Pengcheng Yu, Fumiomi Takeda and Gerard Krewer

manufacturers of blueberry harvesters will be able to improve their current designs, which could lead to improved fruit quality and enhanced highbush blueberry production efficiency. Units Literature cited Brown, G.K. 1983 Status of harvest mechanization of

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S. Kaan Kurtural, Andrew E. Beebe, Johann Martínez-Lüscher, Shijian Zhuang, Karl T. Lund, Glenn McGourty and Larry J. Bettiga

vineyard management that have increased production efficiency along with the ability to improve yield and berry composition. Recent vineyard mechanization research performed in California in a climate corresponding to Region V of the Winkler scale [>2222