Authors:
Nwogha J. S., Agenbag G. A., Amadi C. O., Obidiegwu J. E. and Oselebe, H. O ,South Africa |
Abstract:
The objective was to screen some canola genotypes for heat tolerance and possible selection of
heat tolerant genotypes for planting at more tropical South Africa regions. The study was
conducted for two years in glass house of department of Agronomy, University of Stellenbosch
South Africa. Randomized complete block design was used. Seven canola genotypes selected
from early and mid-maturing groups of canola genotypes presently planted in the Western Cape,
South Africa canola production area were grown in 3 litre plastic bags filled with a mixture of
sand and compost at ratio of 1:1 and irrigated with fully balanced nutrient solution at EC=2.0 in
two glasshouses at night/day temperature regimes of 10/15oC and 15/20oC. Number of days,
growing degree days (GDD) and photothermal units (PTU) from planting to visible flower buds
appearance, first flower opening, seed ripening and seed physiological maturity were recorded.
Plants were sampled for leaf area (LA) and above ground dry mass (DM) at budding, flowering
and seed physiological maturity stages. Days after planting, GDD and PTU at budding, flowering
and physiological maturity were correlated with leaf area, dry mass, number of pods plant-1 and
pod dry mass plant-1 at budding, flowering and physiological maturity stages to determine
whether there were relationships between the variables. The results showed that increasing daily
mean temperature from 12.5?C to 17.5?C, on average, reduced the duration of flowering time by
10.38 days, time to beginning of seed-filling by 25.39 days and from planting to physiological
maturity by 28.09 days. However, there were variations among canola genotypes with regard to
heat tolerance. These reductions in the duration may however change if plants were grown at
different day lengths. Increased GDD and PTU due to higher mean daily temperatures decreased
the total above ground dry mass, number of pods plant-1 and pods dry mass at final harvest |
