ABSTRACT
ABSTRACT Melon is one of the most important vegetable crops in the world. With short cycle in a system of phased planting, phytosanitary control is compromised, and a great volume of agricultural chemicals is used to control vegetable leafminer. Genetic control is an ideal alternative to avoid the damage caused by this insect. Thus, the aim of this study was to evaluate Cucumis accessions in regard to resistance to leafminer and correlate the variables analyzed. Fifty-four accessions and four commercial hybrids of melon were tested. The study was divided into two experiments: with and with no choice. The following characteristics were evaluated: with choice, in field - subjective score based on the infestation and the number of mines per leaf; and with no choice, in cage - number of mines per leaf, chlorophyll content, and leaf colorimetry. The results showed variability among the accessions and some genotypes showed favorable results for resistance in both experiments. There was correlation between the two variables in the experiment in the field. The accessions CNPH 11-282, CNPH 06-1047, and CNPH 11-1077 are the most recommended for future breeding programs with aim on introgression of resistance to vegetable leafminer in melon.
Subject(s)
Animals , Phenotype , Pest Control, Biological/methods , Plant Leaves/genetics , Cucumis melo/genetics , Diptera , Genotype , Plant Diseases/prevention & control , Reference Values , Genetic Variation , Chlorophyll/analysis , Genes, Plant , Colorimetry/methods , Statistics, Nonparametric , Plant Leaves/chemistry , LarvaABSTRACT
A mutagenesis programme was carried out using physical mutagens (gamma rays) on Cucumis melo cv. Bathasa. In irradiated seeds the number of shoots formed in the lower doses was significantly higher than the controls. Decrease in the number of shoots and shoot bud formation was observed with higher doses in all the explants studies. There was complete lethality in the 10, 15 and 20 kR doses. In irradiated stem cultures the maximum number of shoots were observed in 2 kR. The number of shoots decreased with increasing doses of irradiation. At higher doses of 4 and 5kR, light green compact callus was formed in almost all the explants. The effect of lower doses of gamma irradiation on shoot bud formation and rooting efficiency from nodal explants cultured on MS +2.0 mgl(-1) L-glutamic acid + 0.5 mgl(-1) BAP, stimulation of shoot and root induction were studied. The number of shoots and root lengths decreased with the increasing dosage of irradiation. The irradiated callus was grown on solidified MS medium with containing 2.0 mgl(-1) BAP + 1.0 mgl(-1) IAA. There was a significant stimulation of growth in the callus at lower doses. At higher doses like 15 and 20 kRs growth was drastically reduced.