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  • Author or Editor: B. L. Koch x
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Abstract

Growth of seedlings of apple (Malus sp.) and pear (Pyrus sp.) was significantly greater in 14 out of 19 chloropicrin-fumigated-pear sous as compared to the nonfumigated check soils. Increase in seedling growth in the 14 soils varied from 50% to more than 400% with both apple and pear. The lack of response of pear and apple seedlings to soil fumigation in 5 soils may be due to low soil pH, high soil arsenic levels and high soil phosphorous fixing capacity. Counts of plant parasitic nematodes (primarily Pratylenchus spp.) were generally low in all but one soil.

Open Access

Abstract

Incorporation of phosphorous into fumigated soil at planting increased the height, dry weight, and P level in seedlings of apple (Malus domestica Borkh.). Non-mycorrhizal plants exhibited a twenty-fivefold growth response to P and obtained maximum size at 200 mg additional P/kg soil. Mycorrhizal plants exhibited less growth response to P (3.2 × increase) but had greater maximum growth (78.0 vs. 67.9 cm) than nonmycorrhizal plants. Maximum growth of mycorrhizal plants occurred with the addition of 100-200 mg P/kg soil.

Open Access

Abstract

Apple trees (Malus domestica Borkh.) grown in soil fumigated with methyl bromide showed a significant increase in growth as measured by trunk circumference. The increase in trunk circumference from fumigation varied from 33 to 49% after 6 to 8 years. Fruit production increased from 2- to 4-fold during the same period. Soil pH, soil arsenic and nematode counts were not considered to be major factors in the lack of growth and fruit production for trees grown in unfumigated soil.

Open Access

Water and carbon budgets of individual citrus fruit were determined throughout their growth to quantify the demand for sucrose and water relative to developmental changes. Fruit transpiration, water accumulation, photosynthesis, respiration, and C gain were measured during this period for grapefruit (Citrus paradisii Macf.) and calamondin (Citrus madurensis Lour.). On a whole-fruit basis, estimated rates of grapefruit transpiration and mean daily water inflow decreased after the first third of development, whereas water apparently was lost freely throughout growth of the smaller, thin-peeled calamondins. Estimates of daily fruit C import remained relatively similar during the majority of grapefruit growth, increasing rapidly only as fruit neared maturation. A similar trend was observed in calamondins, although rates were more variable. Overall, estimated mean daily water inflow into “developing grapefruit decreased relative to that of sucrose inflow, resulting in a progressively higher ratio of sucrose transport to net water inflow. Values for these ratios rose from ≈; 10 to >300 g sucrose/liter of water, reaching levels of net water and sngar transfer that could both be accommodated by citrus phloem alone. Any additional entry into grapefruit appears to have been offset by xylem back-flow, because no other net water influx was observed.

Free access

Abstract

Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe, inoculation increased apple (Malus domestica Borkh.) seedling growth in 3 of 5 fumigated orchard soils without supplemental phosphorous. Mycorrhizae improved seedling growth in only one soil receiving additional P. Increasing P rates up to 100–200 mg/kg improved growth in only one soil receiving additional P. Increasing P rates up to 100–200 mg/kg improved growth of nonmycorrhizal-treated apple seedlings in 4 of 5 soils tested. The 5th soil had an adequate P content, 60 mg/kg soil prior to the addition of P. Mycorrhizal root infection of seedlings growing in soil that received G. mosseae inoculum decreased with increased P rates applied. Some infection was found in seedlings from all soils inoculated with mycorrhizae at P rates of 0–400 mg/kg, and seedlings from 2 of the mycorrhizal soils had infection at the P rate of 600 mg/kg.

Open Access