Canola (Brassica napus L) Seed Yield and quality as affected by planning date and varieties@@@تأثير موعد الزراعة والصنف على محصول البذور وجودتها في الكانولا

This study was carried out during the 2004/2005 and 2005/ 2006 seasons at the Agricultural Research Station, Hadda El-Sham, King Abdulaziz University. Five planting dates during the period from Nov.-15 to Jan.-16 and three canola varieties, Sero-4, Sero-6 and Pactole were studied in a split plot design experiment. Plant height was significantly affected by planting date in linear and cubic responses. Number of fruits/plant showed significant linear, quadratic and cubic responses as affected by planting date. Significant linear and cubic effects were detected for seed yield/ha and oil content, while protein content was significantly affected in linear quadratic and cubic effects. Dec.-1 planting produced the highest mean values of plant height (122.40cm), number of fruits/plant (246.65), seed yield/ha (1320kg) and oil content (41.13%) but the mean values of the previous traits decreased as planting date delayed. Protein content was highest (30.69) in the Jan.-16 planting date and lowest (24.50) in the Nov.-15 planting date. Pactole variety was the best variety in plant height (106.8cm), number of fruits/plant (226.27), seed yield/ha (1200 kg) followed by Sero-4 and Sero-6, respectively. Sero-6 produced the highest oil content (37.14%), followed by Pactole and Sero-4, respectively. Sero-4 produced the highest protein content (28.5) followed by Pactole and Sero-6, respectively. Introduction Canola (Brassica napus L.) is one of the main oil seed crops in the world. Canola has a high adaptability under the different environmental conditions especially under the drought, salinity and temperature stresses. Planting date is critical, since if canola is planted too early or late, and the acceptable planting 13 JKAU: Met. , Env. & Arid Land Agric. Sci., Vol. 18 No. 1, pp: 13-20 (2007 A.D. / 1428 A.H.) F.S. El-Nakhlawy and M.O. Ghandorah 14 dates are based upon location and elevation (Martin, 2006; Fink 2006) stated that planting date is one of the most important production decisions. Taylor and Smith (1992) concluded that seed and oil yields declined when sowing date is delayed. Johnson, et al., (1995) evaluated three canola cultivars at four sowing dates and found that seed yield was the highest at the first two sowing dates. Reduced yield at later sowing was attributed to fewer pods/plant. Shafique, et al., (1999) in Pakistan on ten canola varieties found that delaying planting date significantly increased Aphid population density and caused poor plant growth, and consequently low yield. Kirkland and Johnson (2000) stated that seed yield and oil content were greater in the early planting dates and smaller in the later planting dates. In Australia, Hocking and Stapper (2001) stated that late sowing usually resulted in a great reduction in canola oil content. Brennan, et al., (2002) revealed that oil content in canola seed decreased with an increase in protein. In USA, Horton (2006) found that highest yield of canola was observed from earlier plantings. Materials and Methods The present study was carried out during the two successive seasons of 2004/ 2005 and 2005/2006 at the Agriculture Research Station at Hada El-Sham and Laboratories of the College of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, KSA. Split-plot design experiment with four replicates was conducted in each season according to Gomez and Gomez (1976). Main plot treatments were five planting dates, Nov.-15, Dec.-1, Dec.-16, Jan.-1 and Jan.-16 in each season, while the sub plot treatments were three canola varieties, Pactole, Sero-4 and Sero-6. Sub plot size was 3 m long and 2.1 m apart with 35 cm between each two rows and 20 cm between each two hills in each row. The recommended other agriculture practices were done in the experiment. At harvesting for each planting date, ten random guarded plants in each sub plot were tagged. The following traits were measured on them: plant height (cm), number of fruits/plant then the seed yield/ha was determined from the yield of the inert four rows and converted into kg/ha. Oil content in the seeds was determined using soxhlet instrument and seed protein content was determined using Kjeldahl instrument according to A.O. A.C. (2000). Statistical analysis was done for each trait according to Steel and Torrie (2000) using SAS (2000). Results and Discussion The results of planting date and variety as combined of analysis of variance for the 2004/2005 and 2005/2006 seasons are presented in Tables 1 and 2. Mean squares of plant height under the effects of five planting dates and three canola Canola (Brassica napus L.) Seed Yield and Quality. 15 varieties showed significant effects for planting date and varieties at 0.05 level of probability (Table 1) but no significant effects were found for the 2-factor or 3-factors interactions (Table 1). Partitioning planting date mean squares (Table 1) showed that linear and cubic effects were detected at 0.01 and 0.05 levels of probability respectively, while quadratic and quartic effects for planting date were not significant (Table 1). These results are confirmed with the results of Brennan, et al., (2002) and Horton (2006). Significant effects were found for the response of number of fruits/plant to planting date and varieties at 0.01 level of probability (Table 1). Number of fruits/plant responded to planting date in linear and quadratic forms at 0.05 and 0.01 levels of probability, respectively, but no significant effects were shown for cubic or quadratic effects. Table 1. Mean squares of combined analysis of variance of plant height, and number of fruits/plant under the effects of five planting dates of three canola varieties over 2004/2005 and 2005/2006 seasons. S.O. V. df Plant height No. of fruits/plant Seasons(S) 1 456.90 NS 323.67 NS Rep/S 6 321.5