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Open access

William V. Welker Jr. and D. Michael Glenn

Abstract

Peach [Prunus persica (L.) Batsch] trees were planted in four soil management systems (cultivated, herbicide, mowed sod, and killed sod) in 1982 and grown through 1984. A companion study was established in 1984 with three systems (cultivated, herbicide, and killed sod). Tree growth and fruit yield were greatest when trees were planted and managed in a killed sod system. Establishing a living sod before planting the trees, and then killing the sod with herbicides, prevented the depletion of soil organic matter and increased water infiltration rates, aggregate stability, macroporosity, and microbial respiration rates compared to conventional systems. The changes in soil structure persisted for 2 to 3 years.

Open access

Stephen S. Miller and D. Michael Glenn

Abstract

Calcium nitrate applied annually at rates ranging from 22.5 g actual N per tree (0.5 N, one-half the recommended rate) to 363 g/tree (8 N) and adjusted according to tree age did not influence the growth of 4 apple (Malus domestica Borkh) cultivars (‘Golden Delicious’, ‘Triple Red Delicious’, ‘Red Yorking’, and ‘Stayman 201’) on EM 7a rootstock. There was a significant soil management (herbicide, clean cultivation, or mowed sod) × rate interaction; trees in mowed sod responded to additional N with growth and leaf N levels comparable to the vegetation-free management systems at 4 times (4 N) the recommended rate (45 g N/tree/year age). Soil management and rate of fertilization influenced leaf N levels but not leaf Ca. Leaf N and Ca differed significantly among the 4 cultivars. Cumulative yield after 4 growing seasons was influenced by tree size and soil management, but not rate of fertilization. Soil pH was significantly higher under sod than under cultivated or herbicide strip culture. Soil Ca levels were not affected in the 0 to 30 cm profile. Residual soil NO3-N did not accumulate in the surface 30 cm for any of the management systems except at the highest rate (8 N) under the cultivated and herbicide systems. Data for residual NO3-N in the 0 to 120 cm soil profile indicated that the tree demand and leaching potential for NO3-N was met at the 0.5 N rate when competition was eliminated and between the 2 N and 4 N level in mowed sod.

Free access

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

Reduced availability of water for agricultural use has been forecast for much of the planet as a result of global warming and greater urban demand for water in large metropolitan areas. Strategic improvement of water use efficiency (WUE) and drought tolerance in perennial crops, like fruit trees, could reduce water use without compromising yield or quality. We studied water use in apple trees using ‘Royal Gala’, a relatively water use-efficient cultivar, as a standard. To examine whether genes useful for improving WUE are represented in a wild relative genetically close to M. ×domestica, we surveyed Malus sieversii for traits associated with WUE and drought resistance using material collected from xeric sites in Kazakhstan. This collection has been maintained in Geneva, NY, and surveyed for various phenotypes and has been genetically characterized using simple sequence repeats (SSRs). These data suggest that most of the diversity in this population is contained within a subpopulation of 34 individuals. Analysis of this subpopulation for morphological traits traditionally associated with WUE or drought resistance, e.g., leaf size and stomata size and arrangement, indicated that these traits were not substantially different. These results imply that some of the genetic diversity may be associated with changes in the biochemistry, uptake, and/or transport of water, carbon, or oxygen that have allowed these trees to survive in water-limited environments. Furthermore, genes responding to drought treatment were isolated from ‘Royal Gala’ and categorized according to the biological processes with which they are associated. A large fraction of upregulated genes from roots were identified as stress-responsive, whereas genes from leaves were for the most part associated with photosynthesis. We plan to examine expression of these genes in the M. sieversii population during water deficit in future studies to compare their patterns of expression with ‘Royal Gala’.

Free access

D. Michael Glenn, Nicola Cooley, Rob Walker, Peter Clingeleffer, and Krista Shellie

Water use efficiency (WUE) and response of grape vines (Vitis vinifera L. cvs. ‘Cabernet Sauvignon’, ‘Merlot’, and ‘Viognier’) to a particle film treatment (PFT) under varying levels of applied water were evaluated in Victoria, Australia, and southwestern Idaho. Vines that received the least amount of water had the warmest canopy or leaf surface temperature and the lowest (more negative) leaf water potential, stomatal conductance (g S), transpiration (E), and photosynthesis (A). Vines with plus-PFT had cooler leaf and canopy temperature than non-PFT vines; however, temperature difference resulting from irrigation was greater than that resulting from PFT. In well-watered vines, particle film application increased leaf water potential and lowered g S. Point-in-time measurements of WUE (A/E) and g S did not consistently correspond with seasonal estimates of WUE based on carbon isotope discrimination of leaf or shoot tissue. The response of vines with particle film to undergo stomatal closure and increase leaf water potential conserved water and enhanced WUE under non-limiting soil moisture conditions and the magnitude of response differed according to cultivar.

Free access

D. Michael Glenn, Ernesto Prado, Amnon Erez, James McFerson, and Gary J. Puterka

Particle film technology is a new tool for tree fruit production systems. Trials were performed in Santiago, Chile, and Washington and West Virginia to evaluate the effect of particle film treatments on apple [Malus sylvestris (L.) Mill var domestica (Borkh.) Mansf.] fruit temperature and the incidence of solar injury. Fruit surface temperature was reduced by the application of reflective particles and the amount of temperature reduction was proportional to the amount of particle residue on the fruit surface. Effective solar injury suppression was achieved with spray applications of 45 to 56 kg·ha-1 of a reflective, processed-kaolin particle film material in concentrations ranging from 3% to 12% in some of the locations. The timing of application to suppress solar injury was not clearly defined. The processed-kaolin particle film material was highly reflective to the ultraviolet wavelengths and this characteristic may be important in reducing solar injury to both fruit and leaves.

Open access

Donald L. Peterson, Ralph Scorza, Stephen S. Miller, and D. Michael Glenn

Abstract

Six cultivars and three advanced breeding selections of fresh-market peaches (Prunus persica Batsch.) were evaluated for once-over mechanical harvesting. Factors evaluated were uniformity of maturity, fruit size, and incidence of damage in firm-ripe fruit. Harvest date was determined by estimating visually when equal amounts of green and over-ripe fruits were on the tree. In practice this criterion was difficult to achieve. Only on two occasions during the 2-year test did the proportion of firm-ripe fruit exceed 80% of total harvested fruit. Mean incidence of damage due to mechanical harvesting ranged between ≍2% and 12%. Nonuniformity of maturity of fruit on a given tree is a major hindrance to once-over harvesting of peaches.

Full access

D. Michael Glenn, Stephen Drake, Judith A. Abbott, Gary J. Puterka, and Patricia Gundrum

Experiments were performed over 3 years to examine the effect that particle film (PF) treatment had on fruit quality of several apple (Malus ×domestica) cultivars in Washington and West Virginia. In the first study, a highly reflective, white, hydrophilic particle-based kaolin mineral (Surround WP) was applied to `Empire' apple in May and June, on a season-long basis, or not at all. Red fruit color was increased by both the PF treatments compared with no treatment in all years. In a second study, the PF material was applied, starting at petal fall, every week for 6 weeks and then every 2 weeks until harvest to `Empire', `Gala', and `Fuji' trees in West Virginia and to `Cameo', `Fuji', and `Gala' trees in Washington. In the latter study, cultivar response to season-long applications varied by year and location. `Empire' consistently had improved red color with season-long applications of PF materials. `Gala' had greater fruit weight and red color with PF application in 1 of 2 years in West Virginia but not in Washington. `Fuji' had greater fruit weight and soluble solids content and `Cameo' had greater soluble solids, higher starch indices, and greater red color in Washington with the PF application. In these studies, application of a PF never reduced the surface red color in apples. A taste panel did not identify quality differences in `Empire' apples treated with PF vs. the control. Cultivar responses to PF applications were variable due to location and yearly environmental characteristics. While particle film technology has value for insect control and reducing sunburn, it has limited value to enhance fruit color due to the inconsistent response.

Free access

Gary W. Stutte, Tara A. Baugher, Sandra P. Walter, David W. Leach, D. Michael Glenn, and Thomas J. Tworkoski

A study was conducted to quantify the effects of rootstock and training system on C allocation in apple. Dry-matter distribution was determined at harvest in 5-year-old `Golden Delicious' apple (Malus domestica Borkh.) trees on four rootstocks (MM.111 EMLA, M.7a, M.26 EMLA, and M.9 EMLA) and in three training systems (three-wire palmette, free-standing central leader, and nonpruned). Mobilizable carbohydrate content was determined at harvest and leaf fall in trees from the same planting on MM.111 EMLA and M.9 EMLA in all three training systems. Training system effects interacted with rootstock effects in dry weights of branches and of fruit. Nonpruned system shoot and fruit dry weights reflected known rootstock vigor; whereas, pruned system (three-wire and central leader) shoot dry weights were greatest and fruit dry weights were lowest in trees on M.7a. Rootstock affected the partitioning of dry matter between above- and below-ground tree components, with MM.111 EMLA accumulating significantly more dry matter in the root system than trees on the other rootstocks. Trees in the central leader and the three-wire palmette systems partitioned more dry weight into nonbearing 1-year shoots than trees in the nonpruned system. Root starch content at harvest was greater in trees on MM.111 EMLA than on M.9 EMLA, and root sucrose and sorbitol were less in trees on MM.111 EMLA compared to M.9 EMLA. At leaf fall, starch in young roots was equal in trees on both rootstocks, and sorbitol again was lower in trees on MM.111 EMLA. Harvest starch content of roots, shoots, and branches was lower in nonpruned than in pruned trees. At leaf fall, root, shoot, and branch starch content increased in nonpruned and central leader-trained trees but did not increase in three-wire palmette-trained trees.

Free access

D. Michael Glenn, Gary J. Puterka, Stephen R. Drake, Thomas R. Unruh, Allen L. Knight, Pedro Baherle, Ernesto Prado, and Tara A. Baugher

Particle film technology is a developing pest control system for tree fruit production systems. Trials were performed in Santiago, Chile, and York Springs, Pa., Wenatchee and Yakima, Wash., and Kearneysville, W. Va., to evaluate the effect of particle treatments on apple [Malus sylvestris (L.) Mill. var. domestica (Borkh) Manst.] leaf physiology, fruit yield, and fruit quality. Leaf carbon assimilation was increased and canopy temperatures were reduced by particle treatments in seven of the eight trials. Yield and/or fruit weight was increased by the particle treatments in seven of the eight trials. In Santiago and Kearneysville, a* values of the fruit surface were more positive in all trials although a* values were not increased in Wenatchee and Yakima. Results indicate that particle film technology is an effective tool in reducing heat stress in apple trees that may result in increased yield potential and quality.