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Wei Qiang Yang and Barbara L. Goulart

Aluminum (Al) and phosphorus (P) interactions were investigated in mycorrhizal (M) and nonmycorrhizal (NM) highbush blueberry (Vaccinium corymbosum L.) plantlets in a factorial experiment. The toxic effects of Al on highbush blueberry were characterized by decreased shoot, root, and total plant dry mass. Many of the negative effects of Al on plant root, shoot, and total dry matter production were reversed by foliar P and N application, indicating P or N uptake were limited by high Al concentration. However, Al-mediated growth reduction in P-stressed plants indicated that the restriction of P uptake by high Al may not have been the only mechanism for Al toxicity in this experiment. Root Al and P concentration were negatively correlated in NM but not M plantlets, suggesting mycorrhizal infection may alter P uptake processes. Al uptake was also affected by mycorrhizal infection, with more Al accumulating in M plantlet roots and leaves. Correlations among foliar ion concentrations were also affected by mycorrhizal fungal infection.

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Entin Daningsih, D. L. Coffey, J. Logan, and C. A. Mullins

97 ORAL SESSION (Abstr. 542-548) VEGETABLE CROPS: GROWTH AND DEVELOPMENT

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Jasim Uddain, Sanzida Islam Tripti, Mohammad Shah Jahan, Nasrin Sultana, Md Jahedur Rahman, and Sreeramanan Subramaniam

al., 2015 ). Vermicompost also significantly stimulates the growth and productivity of plants ( Edwards, 1998 ). Vermicompost is used as organic fertilizer to improve soil aeration and enhance soil microorganisms, plant growth, and eventually crop

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Jack D. Early Jr. and George C. Martin

33 ORAL SESSION (Abstr. 391-397) FRUIT CROPS: GROWTH AND DEVELOPMENT I

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Patricia I. Garriz, Hugo L. Alvarez, and Angel J. Alvarez

145 POSTER SESSION (Abstr. 694–707) Growth and Development–Tree Fruits

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J.E. Barrett, C.E. Wieland, T.A. Nell, and D.G. Clark

76 ORAL SESSION 13 (Abstr. 478-483) Floriculture: Postharvest Physiology/Plant Growth Regulators

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Duane W. Greene

86 WORKSHOP 11 (Abstr. 682-684) Dynamics of Fruit Growth Tuesday, 25 July, 10:00 a.m.-12:00 noon

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Muntubani D.S. Nzima, George C. Martin, and Chic Nishijima

We investigated the development of leaf area (LA) and the distribution of dry matter within branches of 25-year-old, alternate-bearing `Kerman' pistachio (Pistacia vera L.) trees that were in their natural “on” (heavy) or “off” (light) bearing cycles to determine the immediate and delayed effects of fruiting on shoot growth. Compared to “off” trees, individual leaves of “on” trees were greater in number and expanded twice as fast during the first 30 days after full bloom (FB) (FB + 30). Mature, fully expanded leaves of “on” trees were smaller (124.1±3.26 cm2) than those from “off” tree (163.3±3.40 cm2), indicating delayed demands of fruiting on initial leaf growth. Total LA per current shoot was greater in “on” than “off” trees because shoots of “on” trees averaged eight leaves, compared with six for “off” trees. More inflorescence buds per shoot (seven vs. three buds) abscised from “on” than from “off” trees. About 60% of the young developing nuts had abscised by FB + 30 when they weighed <250 mg each and another 25% abscised between FB + 30 and FB + 60 when individual nuts weighed ≈400 mg. The average total dry mass (DM) of individual branches of “on” trees increased 1322% (5·9 to 83·9 g) compared to 598% (4·2 to 29·3 g) in “off” trees. Besides nuts, leaves accumulated the greatest amount of dry matter within individual branches followed in decreasing order by current wood, 1-year-old wood, and inflorescence buds. DMs of individual leaves of “on” trees averaged between 15% and 48% greater than leaves of “off” trees. “Off” trees invested 4.6 g of dry matter into individual 1-year-old wood and 2.1 g into current wood. “On” trees, however, invested 1.3 g of dry matter into 1-year-old wood and 4.3 g of dry matter into current wood. One-year-old wood was an important major source of carbohydrates for developing leaves, current wood, rachises, and nuts. The immediate demands of fruiting on individual components of a branch were measured as losses in DMs. Individual leaves, current wood, 1-year wood, and rachises lost 1.1%, 0.3%, 1.1%, and 1.0%, respectively, of the average total DMs of individual branches of “on” trees. This loss was equivalent to 5.7%, 5.9%, 26.7%, and 16.4%, respectively, of the seasonal average peak DMs of the respective individual components of the branch.

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Bandara Gajanayake, K. Raja Reddy, Mark W. Shankle, and Ramon A. Arancibia

grown under furrow or drip-irrigated conditions in California ( Stoddard et al., 2013 ). Soil moisture stress is one of the crucial abiotic stress factors that limits growth and development of sweetpotato, affecting storage root production and yield

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Wlodzimierz Bres and Leslie A. Weston

`Buttercrunch', `Grand Rapids', and `Summer Bibb' lettuce (Lactuca sativa L.) seedlings were grown with the nutrient film technique (NIT). The influence of two K concentrations (150 and 225 mg·liter-1) and four solution pH levels (5.0, 5.5, 6.0, and 6.5) on lettuce tipburn was investigated in four experiments. Additionally, the influence of pH on foliar nutrient concentration was examined. Even though tipburn was observed in `Buttercrunch' and `Summer Bibb' lettuce, neither K nor pH level consistently affected tipburn incidence. No tipburn was observed in `Grand Rapids'. Solution pH generally did not affect concentration of total N and NO3-N in lettuce tissue. Increasing the pH increased K concentration and resulted in increased proportions of K compared to Mg or Ca. Although the influence of solution pH on P, Ca, and Mg concentration was significant, nutrient accumulation differences were not reflected in lettuce fresh-weight differences. The influence of K solution concentration and pH on lettuce yield was not significant. Tipburn incidence in NIT-produced lettuce appears to be primarily affected by environmental conditions maintained during greenhouse growth.