Whenever supplemental irrigation was applied to sweet potatoes, root quality was reduced. Dry matter content, color of both fresh and processed sweet potatoes, firmness of the canned product, and percent protein decreased as the moisture content of the soil increased. Moisture content had little or no influence on fiber content or cortex thickness of fleshy roots. Nitrogen levels also influenced quality factors. As N levels increased there was a reduction in flesh color and increases in protein content and firmness of the canned potatoes. Nitrogen had little effect on fiber content, dry matter content or cortex thickness. Yearly variations occurred for dry matter content, fiber content, firmness of the canned product and flesh color.

Fruit set of 6 genotypes of tomato (Lycopersicon esculentum Mill) ranged from 50% (BL6807) to l% (L401) in the summer and from 93% (BL6807) to 78% (L401) in the spring. Flower drop was significantly higher in the summer for each cultivar, except for BL 6807 where there was no difference. All genotypes had significantly more underdeveloped ovaries in the summer and generally less normal pollen, smaller fruit, and less seed per fruit. Although these variables were related to low fruit set at high temperatures, they were not primarily responsible for this character.

No abstract

Seven tomato genotypes (Lycopersicon esculentum Mill) were crossed in all except reciprocal combinations in a diallel test for heat tolerance. S6916 had the highest general combining ability (GCA) value for heat tolerance, indicating that it transmitted good fruit setting abilty at high temperatures to its progeny. BL6807 had the second highest GCA value for fruit set but also transmitted underdeveloped ovaries. L401 had the lowest GCA value for fruit set. Additive gene action was more important than nonadditive effects for fruit set, flower drop, and underdeveloped ovaries at high temperatures.

Breeding lines and cultivars of sweet potato, Ipomoea batatas (L.) Lam were evaluated in the field during a 4 year period for resistance to the sweet potato weevil, Cylas formicarius elegantulus (Summers). Appreciable resistance occurred in lines from Louisiana, Nigeria, Asia, and the U.S. Vegetable Laboratory. Lines performed similarly with respect to resistance when evaluated in 2 or more years.