Evaluation of environmental factors, affecting meal glocosinolate content in canola (B. napus)

The effect of different environmental factors, such as water used in evapotranspiration and air temperature (AT) during seed filling period, on meal glocosinolate content (MGC) of two canola (Brassica napus) cultivars, was evaluated at Agricultural Research Station of Gonbad, Golestan, in a 2-year study (2005-7). The experiment was a randomized complete block design arranged in a split-plot in two conditions, i.e. supplemental irrigation (SI) and rainfed (RF). Two cultivars of canola (Hyola 401 and RGS003) as subplots were grown at 5 sowing dates (SD) as main plots, with a span of approximately 30 days apart, to obtain different environmental conditions. In both years, SI caused decrease of MGC. The mean MGC in IR and RF conditions was 12.0 and 15.6 μmol/g dry matter (DM) in 2005-6, and 11.7 and 13.2 μmol/g DM in 2006-7, respectively. The negative relationships between MGC with crop water used, and leaf relative water content (LRWC) showed that optimum environmental conditions could have an importantrole in reducing of MGC. MGC was considerably affected by SD, and AT during seed filling period. An increase of 0.087 and 0.11 μmol/g DM of MGC of Hyola 401 hybrid and RGS003 cultivar respectively, for each day delay in SD from November 5, indicating more susceptibility of RGS003 to SD, compared to Hyola 401. Also, with an each degree increase in mean temperature during seed filling stage, MGC increased 1.30 and 1.34 μmol/g DM, for Hyola 401 and RGS003 cultivars, respectively. In overall, MGC was affected by environmental factors during critical period of seed filling. MGC was affected by factors, such as water used in evapotranspiration, LRWC, AT during seed filling period, duration of seed filling period, SD and cultivar.