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  • Author or Editor: W. B. Collins x
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Abstract

Carbon dioxide enrichment of the greenhouse atmosphere, either in the period prior to tuberization or during the tuber development period of potato (Solanum tuberosum L.), increased tuber yield significantly at harvest, compared to yields from plants grown in a conventional atmosphere. Enrichment during the tuber development period provided the greatest increase in tuber dry weight. The data indicated that the increase in yield was attributable to an increase in the net assimilation rate of carbon dioxide enriched plants and a corresponding increase in the relative growth rate.

Open Access

Abstract

The identity of a growth-regulating substance that occurs in flower buds of lowbush blueberry (Vaccinium angustifolium Ait.) subjected to short-day inductive conditions was investigated. The results of Avena bioassay tests and thin layer chromatography led to the conclusion that the growth regulator was similar in its properties to the gibberellins. Under continued exposure to short-day conditions the induced flower buds developed into naturally parthenocarpic fruit.

Open Access

A random sample of 6000 individuals from a recombinant Solanum phureja - S. stentomum hybrid population and 250 individuals of Solanum phureja were twice inoculated with potato virus Y (PVY) strain “o” using the air brush technique. Symptomless seedlings were field transplanted for further evaluation and 1508 seedlings were judged to be resistant to PVY (33%). At harvest, a mild selection pressure for tuber appearance was applied and 602 clones were selected.

Selected clones were re-evaluated for PVY resistance in the greenhouse: twice inoculated with PVY, tested by ELISA (Enzyme-linked immunosorbent assay), graft-inoculated with tobacco PVY infected scions, and subjected to a second ELISA test. To assess immunity to infection by PVY, the ELISA negative clones were bioassayed using tobacco cv. “Burley 21” as a plant indicator. We identified 224 PVY immune clones (4.8%).

Simultaneously, the first year PVY selected clones were twice inoculated with U.S. common strain of potato virus X (PVX). Clones free of PVX symptoms were tested by ELISA. Negative clones were re-inoculated with PVX and symptomless clones were re-tested by ELISA. To assess immunity to infection by PVX, negative clones were bioassayed using Gomphrena globosa as a plant indicator. We identified 7 immune (1.3%); 4 highly resistant and 4 resistant clones. Eight clones showed high levels of resistance to both PVY and PVX (high resistance to immunity).

Free access