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  • Author or Editor: T.K. Hartz x
  • Journal of the American Society for Horticultural Science x
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The feasibility of field-scale CO2 enrichment of vegetable crops grown under tunnel culture was studied with cucumber (Cucumis saivus L. cv. Dasher II), summer squash (Cucurbita pepo L. cv. Gold Bar), and tomato (Lycopersicon escukntum Mill. cv. Bingo) grown under polyethylene tunnels. The drip irrigation system was used to uniformly deliver a CO2-enriched air stream independent of irrigation. Carbon dioxide was maintained between 700 and 1000 μl·liter-1 during daylight hours. Enrichment began immediately after crop establishment and continued for ≈4 weeks. At the end of the treatment phase, enrichment had significantly increased plant dry weight in the 2 years of tests. This growth advantage continued through harvest, with enriched cucumber, squash, and tomato plots yielding 30%, 20%, and 32% more fruit, respectively, in 1989. In 1990, cucumber and squash yields were increased 20%, and 16%, respectively. As performed, the expense of CO2 enrichment represented less than a 10% increase in total preharvest costs. A similar test was conducted on fall-planted strawberries (Fragaria × ananassa Duch. cvs. Irvine and Chandler). Carbon dioxide enrichment under tunnel culture modestly increased `Irvine' yields but did not affect `Chandler'.

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Abstract

Potato tubers of Solanum tuberosum cv. Kennebec, produced at elevations from 1533 to 3198 m at 2 levels of insolation per site were grown in a greenhouse at 1533 m to determine the effect of the parental clone's environment on the performance of the succeeding generation. Rate of emergence, early vegetative growth, and tuber growth increased with increasing elevation of the parental clone but there was no significant difference in vegetative growth or tuber yield at vine senescence. The environment of the parental clone had no direct influence on the photosynthetic activity of the clonal progeny, but an inverse relationship between bulking efficiency and altitude of seed tuber production was evident. Shading of the parental clone at each elevation had little influence on the succeeding generation.

Open Access

Abstract

Effects of solarization and fumigation on control of pink root disease of onion (Allium cepa L.) were determined in microplot studies in 1984. A 62-day solarization treatment significantly improved stand and productivity of ‘Granex 429’ onion while decreasing pink root expression. Metam-sodium fumigation gave equivalent improvement in stand and reduction in pink root expression, while causing an even greater onion growth response. Effects of these soil disinfestation techniques in onion seedbeds on subsequent field performance of onion transplants were examined in 1985–1986. Fumigation and solarization of individual soil beds virtually eliminated Pyrenochaeta terrestris infection of onion transplants. Seedbed treatment had no beneficial effect on yield, bulb diameter, or pink root expression at harvest when transplants were grown to maturity in an infested field. Chemical name used: sodium methyldithiocarbamate (anhydrous) (metam-sodium).

Open Access

A survey of 140 processing tomato (Lycopersicon esculentum Mill.) fields in central California was conducted in 1996-97 to examine the relationship between K nutrition and fruit quality for processing. Quality parameters evaluated were soluble solids (SS), pH, color of a blended juice sample, and the percent of fruit affected by the color disorders yellow shoulder (YS) or internal white tissue (IWT). Juice color and pH were not correlated with soil K availability or plant K status. SS was correlated with both soil exchangeable K and midseason leaf K concentration (r = 0.25 and 0.28, p < 0.01) but the regression relationships suggested that the impact of soil or plant K status on fruit SS was minor. YS and IWT incidence, which varied among fields from 0% to 68% of fruit affected, was negatively correlated with K status of both soil and plant. Soil exchangeable K/√Mg ratio was the measure of soil K availability most closely correlated with percent total color disorders (YS + IWT, r = -0.45, p < 0.01). In field trials conducted to document the relationship between soil K availability and the fruit color disorders, soil application of either K or gypsum (CaSO4, to increase K/√Mg ratio) reduced YS and total color disorders. Multiple foliar K applications were effective in reducing fruit color disorders at only one of two sites. In no field trial did K application improve yield, SS, or juice color.

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