Resistance and tolerance of Commercial onion cultivars to stem and bulb nematode, Ditylenchus dipsaci

Abstract

Nematode resistance and tolerance reactions of 28 onion cultivars grown commercially in Turkey to stem and bulb nematode were studied at 20 °C, 70% RH and 16:8 h L:D photoperiod in growth chamber with 10 replications and at 27±4 °C and 16:8 h L:D photoperiod in greenhouse with 3 replications, respectively. Ditylenchus dipsaci multiplied in all cultivars tested. The lowest multiplication was determined in cv. Valenciana from Atatürk Horticultural Central Research Institute with 91 nematodes/pot and a multiplication rate of 0.5. Plant height of cultivars were significantly different in the first tolerance experiment with having an average plant hight of 33.5 and 103.1 mm for inoculated and inoculated plants, respectively (P<0.05). Onion shoot diameter was statistically greater in nematode inoculated plants with 7.4 mm than inoculated plants with 6.0 mm in second tolerance experiment (P<0.05). Plant weight was not found different in both tolerance experiments with nematode inoculation. There was not any statistically difference among cultivars for plant height, plant diameter, plant weight and nematode multiplication in the experiments. Plant diameter for cv. Betapanko in first tolerance experiment and plant height for the Banko type onion in the second tolerance experiment sustained significant negative correlations with nematode numbers. Plant weight for cv. Biotek Boran in second experiment, plant height for cv. Taraz in second experiment and, plant diameter and plant weight for cv. Taraz in first tolerance experiment sustained significant positive correlations with nematode multiplication. It could be recommended that Valenciana could lower nematode multiplication and Biotek Boran and Taraz could maintain a better plant development in nematode infested onion growing areas.