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EFFECT OF DIFFERENT SOWING DATES ON THE VEGETATIVE AND REPRODUCTIVE GROWTH OF CANOLA (BRASSICA NAPUS L.)   CULTIVARS UNDER DIFFERENT SALINITY LEVELS

 HUMAIRA GUL AND RAFIQ AHMAD

Abstract: Effect of sowing date was investigated on the growth of canola (Brassica napus L.) cv. Oscar and Rainbow under saline water irrigation of different sea salt concentrations. Plants were sown at different dates and subjected to control (non-saline), 0.4% (EC 4.5 dS.m^-1) and 0.6% (EC 6.5 dS.m^-1) of sea salt concentrations. Vegetative growth was recorded in terms of plant height, fresh and dry shoot biomass per plant, while reproductive growth was noted in terms of number of flowers and siliquae seed number and weight per plant. Plant growth on vegetative as well as reproductive phases was found proportionately inhibited with respect of increasing salinity in irrigation water. As far as proper sowing time of Canola in Sind is concerned, the cv. Oscar sown from mid September to late October gave equally good yield in terms of seed weight per plant under non-saline conditions whereas yield in cv. Rainbow sown early (2^nd week of September) was much reduced and the seeds sown during late September till early October gave comparatively better yield. Both of these cultivars when sown on above-mentioned dates and irrigated with different sea salt dilutions showed more or less same pattern of comparative yield as that of good quality water irrigation, though the amount of seed formation per plant was reduced according to the degree of salinization. The yield obtained from the seeds sown in the month of November was considerably reduced in both the cultivars. Maximum temperature has been 36 ⁰C, minimum 24 ⁰C and relative humidity 46% during the month of October which appears to be best season for growing Canola.

Biosaline Research Laboratory, Department of Botany, University of Karachi. Karachi, Pakistan.