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Zhengnan Yan, Dongxian He, Genhua Niu, Qing Zhou, and Yinghua Qu

Plant factories with artificial lighting have many advantages over traditional production systems (e.g., greenhouse and open-field) for leafy greens, herbs, and transplants production because of high resource use efficiency, high productivity, and

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T.E. Thompson and L.J. Grauke

The U.S. Dept. of Agriculture, Agricultural Research Service conducts the largest and oldest pecan [Carya illinoinensis (Wangenh.) K. Koch] breeding program in the world. This program evaluates thousands of nut and kernel samples each year using a standard nut and kernel evaluation system developed and refined for more than 70 years. This report relates the effectiveness of these evaluations to commercial shelling efficiency by direct comparison of these data to commercially shelled samples from the same clone performance test. Visual ratings of shelled kernel samples (1-5, with 1 = best) were correlated with time required to hand clean kernel samples (r = 0.55). As percent kernel increased, visual ratings of shelled kernels improved (decreased) (r = -0.73). More intact halves were recovered from shelled samples with the best (lowest) visual ratings (r = -0.67). Conversely, fewer pieces of any size were present in samples with the best visual ratings. Visual ratings improved as nut density decreased (r = 0.33). Samples with the lightest kernel color also had the best visual ratings (r = 0.38). These data show that the standard U.S. Dept. of Agriculture pecan nut and kernel evaluation system needs to be refined by modifying selection pressure placed on various standard evaluation traits.

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D.C. Fare, C.H. Gilliam, and G.J. Keever

Improved water use efficiency exists for plants grown in modified containers to minimize leaching and reduce irrigation frequency which subsequently reduces NO3-N leachate. Salvia splendens `Bonfire' and Impatiens wallerana `Pink' (super elfin hybrid) were potted in ProMix BX medium (Premier Brands, Inc., Stamford, CT) into nine container styles with modified drainage holes to determine leachate volume and quantify NO3-N leached. Three styles had four drainage holes on the container side with hole diameters of 0.5, 1.0, and 1.9 cm, respectively; three styles had four drainage holes on the container side and one drainage hole in the bottom center with hole diameters of 0.5, 1.0, and 1.9 cm, respectively; and three styles had one drainage hole in the bottom center with hole diameters of 0.5, 1.6, and 1.9 cm, respectively. Plants were hand watered when an individual container's medium reached 80% of container capacity. Leachate volume, irrigation frequency, and leachate NO3-N was reduced as drainage size hole decreased in size and number. Plant quality was similar among container modifications.

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D. Michael Glenn, R. Scorza, and W.R. Okie

Two unpruned narrow-leaf and two unpruned standard-leaf peach [Prunus persica (L.) Batsch.] selections were evaluated for physiological components related to water use efficiency {WUE [carbon assimilation (A) per unit of transpiration (T)]}. The purpose of the study was to assess the value of narrow-leaf phenotypes to improve WUE in peach and separate the environmental component of canopy geometry from the genetic components. The narrow-leaf characteristic itself did not confer improved WUE. The interception of light was a key determinant of WUE in these genotypes. Internal shading of the tree by excessive leaf area reduced daily WUE measured in gas exchange studies. Canopies that intercepted more than 75% of the photosynthetically active radiation (PAR) had reduced daily WUE. Dormant season pruning of the four genotypes lowered isotopic carbon discrimination and therefore increased seasonal WUE compared to unpruned trees. None of the genotypes had a significant correlation of seasonal WUE with leaf and fruit weight. Analysis of covariance indicated that `Bounty' and both narrow-leaf genotypes had greater leaf and fruit weight than `Redhaven' for a given level of PAR interception. `Bounty' had the least internal canopy shading of the four genotypes. Genetic differences in peach growth types can be selected for factors increasing WUE as well as increased productivity. Future work in peach breeding to improve WUE and productivity must take into consideration light interception, productivity, and WUE in an integrated manner to make real progress in the efficient use of water and light in the orchard environment.

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Diana Devereaux and Raul I. Cabrera

High levels of N are often used to produce a vigorous plant that is also aesthetically pleasing to the purchaser. Environmental concerns with the overuse of N raise the need to find the minimum N requirements necessary to produce a salable plant. Ilex opaca and Lagerstroemia indica plants growing in 1.5-gal containers were irrigated with nutrient solutions containing N concentrations of: 15, 30, 60, 120, 210, and 300 mg N/liter. After 4 months, data indicate that using solutions >60 mg N/liter for both plant species results in leachates with N concentrations higher than those in the applied solutions. Nitrogen leaching losses increased with applied N, ranging from ≈15% to 50% for the low and high treatments, respectively. Chlorophyll readings of leaf tissue were not significantly different for plants of both species receiving N solutions higher than 60 mg·liter–1. These results indicate that N levels lower than those typically used for production of these woody ornamentals will still produce salable plants while increasing N fertilizer-use efficiency.

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Luca Corelli-Grappadelli, Gianfranco Ravaglia, and Eugenio Magnanini

Training system efficiency may be defined as the ratio of fruit produced to the amount of light intercepted by the canopy. In apple, a positive, linear relationship between yield and light intercepted is generally found, but in peach similar data are hard to come by. This paper reports data from an ongoing training systems trial now in the 7th year, with trees trained as Y, palmette, and delayed vase. During the life of the orchard, light interception has been measured for the different tree shapes, the yields have been recorded, and, in some years, whole-canopy gas exchanges of cropping trees have been measured. In general, the trees have been intercepting light in amounts proportional to canopy shape and tree density, with the Y (planted at higher density) intercepting more light than the other two systems, which appear more comparable to each other, despite the fact that they intercept light during the day in different ways, with the delayed vase exposing more or less the same leaves to incoming light during most of the day. Cropping has followed the amounts of light intercepted, with higher yields for the Y, without appreciable differences in fruit quality traits. The data accumulated so far indicate furthermore that the palmette and the delayed vase, despite slightly different light interception potentials (lower for the palmette), have similar yields. This might depend in part on the fact that these two systems intercept light according to different patterns during the day, with the palmette—which distributes the light intercepted in a more even fashion between the two sides—perhaps at an advantage over the vase in terms of managing the stress of excessive light (heat) loads during the central hours of the day. Whole canopy Carbon exchange data have been found to be in agreement with the patterns of light interception.

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Olfa Ayari, Martine Dorais, Gilles Turcotte, and André Gosselin

Yield of greenhouse tomatoes has greatly increased during the past decade due to the development of more-productive cultivars and to the use of new technologies, such as supplemental lighting and CO2 enrichment. Under high PPF and p[CO2], however, the capacity of tomato plants to use supplemental energy and CO2 decreases. Our project aimed at determining the limits of photosynthetic capacity of tomato plants under supplemental lighting (HPS lamps, 100 μmol·m–2·s–1, photoperiod of 14 to 17 h) and high p[CO2] (900 ppm). The following measurements were made on the 5th and the 10th leaves of tomato plants at regular intervals from November to May: diurnal changes in net (Pn) and maximum (Pmax) photosynthetic rate, Chla fluorescence of dark-adapted and no dark-adapted leaves, and the soluble sugars and starch contents of the 5th and 10th leaves. Changes in global radiation from 250 W/m2 in winter to about 850 W/m2 in spring resulted in Pn increases of 45% and 42% in the 5th and 10th leaves, respectively. During the winter period, Pmax was higher than Pn, suggesting that leaves were not at maximum photosynthetic capacity. In the spring, no difference was found between Pmax and Pn. Sucrose concentration in leaves increased progressively up to a maximum of 12-h photoperiod, while hexoses remained constant. The Fv/Fm ratio did not vary during winter, but significantly decreased during spring due to photoinhibition. Increases in global radiation during spring resulted in lower photosynthetic rates, higher fluorescence, and starch accumulation in leaves. Data will be discussed in terms of crop efficiency and yield.

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Adolfo Rosati, Andrea Paoletti, Raeed Al Hariri, Alessio Morelli, and Franco Famiani

’ appeared to be almost entirely dictated by the difference in dry matter partitioning into fruit. In a previous study ( Rosati et al., 2017 ), we found that tree growth was inversely related to yield efficiency across 12 olive cultivars over a period of

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Dalong Zhang, Yuping Liu, Yang Li, Lijie Qin, Jun Li, and Fei Xu

t 2 were 20 and 40 d after transplanting in the current study, respectively. Transpired water consumption and WUE. Whole-plant water use efficiency (WUE plant ) was calculated as the ratio of the shoot biomass to the cumulative amount of water

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Chiara Cirillo, Youssef Rouphael, Rosanna Caputo, Giampaolo Raimondi, and Stefania De Pascale

( Table 3 ). Table 3. Effects of irrigation treatments, genotypes, and shapes on number of leaves, total leaf area, number of flowers, and flower density of potted Bougainvillea plants. Water requirement and water use efficiency. Irrespective of genotype