SCREENING OF BANANA HYBRIDS (PHASE II HYBRIDS) FOR RESISTANCE TO HELICOTYLENCHUS MULTICINCTUS
Banana (Musa spp.) which is truly a tropical treasure is being targeted by many pests and diseases. Worldwide, nematodes are considered a very important pest of bananas and plantains, for which control measures are urgently requirement. By damaging the plant root system, nematodes not only hamper the uptake of water and nutrients and consequently the growth and fruit production. Helicotylenchus multicinctus is considered to be an endoparasite in banana. It completes its life cycle within the root cortex where both the sexes, all juvenile stages and eggs can be found. It produces shallow superficial lesions in banana roots which resemble pustule like eruptions. The breeding programme and experiment was carried out at Horticultural College and Research Institute, Department of Fruit Crops, Tamil Nadu Agricultural University, Coimbatore, India and screened against H. multicinctus. The potential diploids and hybrids developed were crossed with commercial triploids to develop primary tetraploids and improved diploids. Banana suckers of uniform size and weight were collected, pared and planted in earthen pot containing 5 kg sterilized pot mixture. The hybrids were evaluated along with the reference cultivars viz., Rasthali (AAB, syn. Silk) as the susceptible reference cultivar and Pisang Lilin (AA) as the resistant reference cultivar. The screening was done based on the root and corm damage assessment as followed in INIBAP Technical Guidelines 7. The reactions of nineteen new synthetic banana phase II hybrids to H. multicinctus was studied under field as well as artificially inoculated pot conditions. The hybrid H 531 (Poovan × Pisang Lilin) exhibited resistance, while hybrids H-02-34, H-03-05, H-03-13, H-03-17, H-04-12, H-04-24, NPH-02-01 and H 510 showed tolerance. The role of biochemical contents like total henols and enzymatic activity like PO, PPO and PAL revealed that they had higher levels of activities in resistant and tolerant genotypes compare to susceptible and highly susceptible ones. The total phenol in the roots was estimated using Folin Ciocalteau reagent and measuring absorption at 660 nm in a spectrophotometer. For enzyme extraction, one gram of root sample per replicate was homogenized with 2 ml of 0.1 M sodium phosphate buffer (pH 7.0) at 4°C. The supernatant was used as crude enzyme extract for assaying PO and PPO. Enzyme extracted in borate buffer was used for estimation of PAL. The PO activity was assessed according to Hammerschmidt and the PPO activity was assessed using the modified method of Mayer. The hybrid H 531 (AAB) took the shortest duration of 213.00 days for shooting and recorded a moderate bunch weight of 13.50 kg.
Das, S.C., Balamohan, T.N., Poornima , K., Seenivasan , N., Velalazan , R., Van den Bergh , I. and De Waele , D. (2014). SCREENING OF BANANA HYBRIDS (PHASE II HYBRIDS) FOR RESISTANCE TO HELICOTYLENCHUS MULTICINCTUS. Acta Hortic. 1026, 37-45
endoparasite, superficial lesions, pustule like eruptions, nemade tolerance, Folin Ciocalteau reagent