The effects of planting date and density on growth, development and yield of two canola (brassica napuls L) cultivars grown under irrigated conditions

Abstract

The effects of planting date and density on growth, development and yield of two canola (Brassica napus L.) cultivars (Hyola 60 and Rainbow) grown at two planting dates was studied during the 2005 and 2006 growing seasons at the Agricultural Research Council- Grain Crops Institute in Potchefstroom in the North-West Province. A field study was conducted during the two growing seasons. The treatments included the two planting dates (Early and Late), two canola cultivars (Hyo la 60 and Rainbow) and four planting densities (in-row spacing of 10, 20, 30, and 45 cm) for 2005 growing season, and for 2006 growing season, a hybrid cultivar was used (Hyola 61 and Rainbow) and planting densities (10, 20, 35, and 60 cm) respectively. The objective of this study was to assess the effect of planting date and density on growth, development and yield of two canola cultivars. The experiment was laid out according to Randomised Complete Block Design (RCBD) with a split-split plot arrangement having three replicates. Each plot was 9m long and 3m wide. There were eight rows per plot spaced 38 cm apart. A single super phosphate (10.5% P) fertilizer was broadcast at a rate of 25 kg/ha just before planting and incorporated into the soil. LAN (28% N) at a rate of 200 kg N/ha (1.93 kg N/plot in 3 slots) was applied at different growth stages. The crop was harvested when seeds had about 35% moisture. Data collected included days to 90% germination, number of days to 50% flowering, dry matter accumulation, number of plants/m2, number of pods/plant, number of seeds/pod, protein and oil content, grain yield, plant height, and 1000-seed weight. The data were subjected to Analysis of Variance procedures of GenStat. The results of this study showed that early planting of canola produced high yield of seed and oil. Increasing planting density in general resulted in a significant increased in vegetative yield, grain yield and plant height but a decrease in number of days to 50% flowering and number of pods/plant. Planting density had no effect on protein and oil contents. Cultivars used in this study responded to treatments the same way except for variables such as dry matter yield, plant height, number of days to 50% flowering, protein and oil contents. Cultivar Rainbow produced significantly the highest amount of protein and oil contents and was the earliest cultivar to flower, whereas, cultivars Hyola 60 had the highest dry matter yield and was the tallest cultivar. In conclusion, sowing canola in May and at the highest plant density (10cm in-row spacing) is recommended for maximizing seed and oil yields under environmental conditions of this study.