The effects of moisture stress on rapeseed (Brassica napus L.)

0iìseed rape is an important crop in canada, Europe, the ussR, china, Japan, lndia, south America, and south Africa.The exact origin of rapeseed is not known, but it is thought to have originated in the Eurasia region.The earl iest references to rape cultivation are from lndia, china, and Japan dating back to 2000 BC (weiss, l9g3).The production of oilseed rape (Brassica napus and B. campestris) is of major economic importance in Canada.Canada is both a leader in production of canola oi I and the worldrs largest exporter of seed.lf Canada is to maintain her position on the international canola market, product i on must be ma i nta i ned or i ncreased.To accompl i sh th i s, environmental factors which ìimit production must be overcome.One such factor is avai lable soi I moisture.The effect of drought on determining yieìd has important impl ications for stabiìity of returns on the Canadian Prairies.l'laximum yield cannot be achieved unless the soil moisture is maintained in the upper half of the available range until pod ripening.Drought during the latter portion of the growing season is a common occurrence on the Canadian Prairies.Rapeseed cultivars are most sensitive to drought stress at flowering.Yieìd, and the yieìd components of pods per p'lant, pods per main branch and seeds per pod have been shown to be significantly reduced by drought (Richards and Thurì ing, l97gb). -tThe interaction