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John Erwin, Tanveer Hussein, and David J. Baumler

5 min (RH; %) and water use efficiency (WUE; WUE = P n /E) among 33 outdoor-grown pepper varieties that vary in indigenous habitat and species. Indigenous habitats used for analysis are shown as superscript numbers after the variety name ( 1 desert

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Katherine F. Garland, Stephanie E. Burnett, Michael E. Day, and Marc W. van Iersel

Iersel, 2008 ; Nemali and van Iersel, 2006 ; Pierzynski et al., 2005 ). A study comparing the efficiency of this irrigation method with cyclic irrigation regulated by timers revealed that, over the course of a month, cyclic irrigation used 30 times more

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Ute Albrecht, David G. Hall, and Kim D. Bowman

, buds, bark pieces, bud sticks, or other tissue types from HLB-affected source plants are used to transmit the pathogen into the phloem of the stem of a healthy plant. Transmission efficiencies are usually high, but this can depend on the type and the

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Aaron L. Warsaw, R. Thomas Fernandez, Bert M. Cregg, and Jeffrey A. Andresen

irrigation efficiency with only 13% to 26% of applied overhead irrigation being retained in the container ( Weatherspoon and Harrell, 1980 ). If not captured, water, fertilizers, and other agricultural chemicals can leave the production area and enter

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Lloyd L. Nackley, Jig Han Jeong, Lorence R. Oki, and Soo-Hyung Kim

nitrogen (N) treatments. Leaf gas-exchange parameters include net CO 2 assimilation rates ( A ), instantaneous leaf water use efficiency (WUE), Rubisco capacity ( V cmax ), and potential electron transport rate ( J max ). The V cmax was significantly

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Carole L. Bassett, D. Michael Glenn, Philip L. Forsline, Michael E. Wisniewski, and Robert E. Farrell Jr

genes regulated by low temperature and photoperiod in peach bark J. Amer. Soc. Hort. Sci. 131 551 563 Blum, A. 2005 Drought resistance, water-use efficiency, and yield potential—Are they compatible, dissonant or mutually exclusive? Aust. J. Agr. Res. 56

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Monica Ozores-Hampton, Francesco Di Gioia, Shinjiro Sato, Eric Simonne, and Kelly Morgan

, respectively. Moreover, seepage irrigation requires large amounts of water, and has an average water use efficiency of 30% to 50% ( Locascio, 2005 ). Seepage irrigation is hence considered one of the least efficient irrigation methods and its use raises several

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Chenggang Wang, Rolf Färe, and Clark F. Seavert

In this paper we analyze the sources of variation in revenue per unit of trunk cross-sectional area (TCA) across a 0.87-ha block of 272 pear (Pyrus communis L.) trees in 2003. Revenue capacity efficiency associated with TCA provides an overall measure of nutrient deficiency and revenue inefficiency caused by environmental constraints in the fruit production process. Data envelopment analysis (DEA) is adopted to estimate revenue capacity efficiency and its components. The deficiencies of macro- and micronutrients are measured and optimal nutrient levels computed for each individual tree. These measures are aggregated for comparing between grids and between rootstocks.

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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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Paula B. Aguirre, Teryl R. Roper, and Armand R. Krueger

The uptake efficiency of apple scions and rootstocks has not been studied in the field. Using 15N (ammonium nitrate, 1 atom % 15N) we compared nitrogen uptake efficiency of 12 rootstocks grafted to one scion (Gala) and of 20 scions on the same clonal rootstock (M.9 EMLA) in orchards located in northeastern Wisconsin. Trees were treated in either Fall or Spring 1998 with 40 g actual N per tree applied as a liquid to the soil. N uptake was assessed by measuring 15N in leaf and wood tissue taken monthly from June to Oct. 1998. Tissues were oven-dried and analized using a ratio mass spectrometer. Treatment differences were greater among scions with the same rootstocks than among rootstocks with the same scion. Total N and 15N content differences were found between roostocks and these values were inversely related to tree size.