Ecology, Environment and Conservation Paper

PARAWILT IN BT COTTON AND ITS AMELIORATION

P.S. Sarlach, P.S. Sekhon, R.S. Sohu and M.S. Gill

Abstract

Parawilt, of cotton, involves sudden drooping of leaves when irrigation is applied after long dry veil. It was first reported in Punjab in khan!. 2004 in lit ( otton hybrid trial. During 2006, serious out break ot Parawilt was observed in Bt cotton Ilybrids in cotton Belt of Punjab. Thereafter, experiments to investigate role of factors like ridge making to reelik e %voter stagnation effect, time of irrigation application and ethylene inhibitors were conducted at tanner's, field where parowilt incidence up to 40% was recorded when irrigated the field after long dry spell. It ‘‘.-,1‘, observed that the symptoms of parawilt started appearing with in 36-48 hrsI applying irrigatik I hiit vis no du lerence iii narawilt incidence when irrigation was applied during morning., en inn, or at night. Rut when ridges were made manually before irrigation, the crop showed no paraw ilt although flat n ligation re'sulted in parawilt. Among the remedial measures, use of ethylene Fodaction inhibitor like '(.)!N,I tOug mt.' was applied before and after irrigation. The foliar application of inhibitor ethylene produAion (Cobalt chloride @ 10 j.ig int,1 during 36-48 hr after irrigation helped in complete 1.1l ,VeiV :m porawiit within 5-7 days of spray. However, there was no recovery when permanent wilimF, has III COL! V set in. 'Ibis investigation immensely demonstrated the beneficial el fect of inhibitors of ethvlecic reduction resulting in recovery of the wilted plants due to neutralization of ethylene i t ion. To cold inn He role of ethylene production in parawilt, such symptoms were artificially induced by applying ethephon - an ethylene producing chemical. These wilted plants showed recovery in a week's time when sprayed with ethylene inhibitors (cobalt chloride or silver nitrate @ 101-tg mL1). The synchrony of parawilt with ethephon application and further recovery by ethylene inhibitors suggested the role of ethylene in causing parawilt.