Combining Ability for Fruit Set, Flower Drop, and Underdeveloped Ovaries in Some Heat-tolerant Tomatoes1

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.

Response of Six Tomato Genotypes under Summer and Spring Weather Conditions in Louisiana1

“…Tuber plug sections were ashed in glass vials for 12 hr at 500°. The ash was suspended in 3 ml of 1 n HC1, and 15 ml of scintillation fluid was added and counted on an IsoCap/300 liquid scin tillation counter (5). Initially, the infiltrated 45Ca was distrib uted as follows: 45% stem end, 20% bud end, and 35% middle section.…”

“…Our conclusion is that none of the above characters could be singled out as solely re sponsible for poor tomato fruit set at high summer temperatures. Hanna et al (5) re ported on the genetic effects of heat tolerance and found that additive gene action played a significant part and was more important than nonadditive effects.…”