Interspecific Breeding for Beet Armyworm Resistance in Celery, Evaluation of Fl Hybrids

Abstract

Abstract The commercial celery ‘Tall Utah’ 52-70R (Apium graveolens L.), the wild species A. prostratum spp prostratum var. filiform (A230 from Australia), and the Fl (A. graveolens X A. prostratum) were obtained from germplasm resources held at the University of California, Davis, Department of Vegetable Crops. Beet armyworm, Spodoptera exigua (Hiibner), larvae were from a laboratory colony maintained on artificial diet at 27 ± 2°C and 16:8 (L:D) photoperiod. Test plants were transplanted into 1-liter pots in University of California soil mixture on 5 March 1991 for replicate 1 and on 3 October 1991 for replicates 2 and 3, and maintained under the same moisture, light, and nutrient regimes in a greenhouse equipped with charcoal filters to remove air pollutants. A one-half strength Hoagland‘s nutrient solution was used to fertilize the plants twice per week. For each replicate, bioassays were initiated 5 months after transplanting by filling 30-ml cups containing agar gel with fresh plant parts (leaf + petiole) of each plant genotype. One neonate beet armyworm was placed in each cup, which then was capped with a plastic lid with pin-holes. The plant tissue was renewed every other day and the agar gel every week. Treatment cups were arranged as a complete block with three replicates of thirty cups per replicate, i.e. a total of 90 cups per genotype were tested. All tests were maintained in environmental chambers at 27 ± 2°C, 75% RH and 16:8 (L:D) photoperiod. Weight of larvae at 7 and 9 days, time to pupation, weight of pupae, time to adult emergence, and survivorship were recorded for each treatment.