Growth and Yield of Some HYVs of Wheat (Triticum aestivum L.) As Affected by Sowing Dates and Soil Moisture

Abstract

The experiment was conducted at the research field of the Department of Botany, Rajshahi University, Rajshahi, Bangladesh. Growth and yield of wheat (Triticum aestivum L.) in relation to sowing dates and soil moisture regime were studied. Four wheat varieties, namely Shatabdi (V1), Gaurav (V2), Shourav(V3) and Kanchan (V4) were tested for the above mentioned parameters. Three sowing dates were November 15, November 30 and December 15 and two soil moisture levels were rainfed and irrigation at every 15 days interval in two growing seasons. Significant sowing time and soil moisture effect was found on different growth attributes in both the experimental years. Generally early sowing and irrigation increased total dry matter (TOM), leaf area (LA) and leaf area index (LAI) at most of the growth stages. Variety Shatabdi (V1) had the highest TOM and lowest in Gaurav (V2) in both the years. The highest leaf area index was in Shatabdi (V1), whereas the lowest in Gaurav (V2). Plant height, leaf number and tiller number at different growth stages were also higher in the early sowing and with irrigation. The highest values of these characters were exhibited by Shatabdi (V1) as well. Crop growth rate (CGR), leaf area ratio (LAR) and relative leaf growth rate (RLGR) were increased due to early sowings (S1 and S2). In addition, most of the growth attributes increased due to irrigation. Relative growth rate (RGR), relative leaf growth rate (RLGR) and specific leaf area (SLA) showed decreasing tendency towards the later stages of growth. All the chara.cters showed their highest values except net assimilation rate in Shatabdi (V1 ). In the present study, yield and yield components were significantly affected by sowing dates and soil moisture regimes. Sowing times significantly influenced the grain yield of wheat. The maximum grain yield was obtained in S1 planting and it was followed by S2 and S3. Irrigated plants had higher growth, development and yield than the rainfed plants for all the varieties. Yield and yield components were significantly affected by sowing times and soil moisture regimes in both the years. Plant height, fertile tiller number per plant, spike length, number of grains per spike, weight of 1000-grain and total dry matter were reduced by delay in sowing time and low soil moisture stress. Simple correlation coefficients between yield and yield components indicated that grain yield was positively correlated with most of the yield components under the three sowing times and the irrigation level. It was also observed that plant height, fertile tiller number per plant, spike length, number of spikelets per spike, grain number per spike and total dry matter per plant was found to be the most closely associated yield components. Path coefficient analysis revealed that fertile tiller number showed the highest positive direct contribution to grain yield followed by number of spikelets per spike, plant height and number of grains per spike in 2005-06 season and plant height, number of grain per spike and spike length in 2006-07 season. Fertile tiller number had positive indirect effects on grain yield via total dry matter. Fertile tiller number appeared to be the important character for getting higher grain yield in wheat. Phenotypic regression analysis was done to select most adaptive genotypes to varying environments. The phenotypic stability of each variety was expressed by two parameters: the slope of regression line and sum of squares of deviation from regression. A stable variety was defined as • one with unit regression (bi= 1) and low deviation from linearity ( S���� =0). Phenotypic regression analysis also showed that Shatabdi (V1) had unit regression slope with low stability value for plant height, grain number per spike, 1000-grain weight and grain yield indicating its stability to varying sowing time and soil moisture treatments. Among the four varieties, Shatabdi (V,) had significantly higher grain yield under all the sowing times and soil moisture conditions. Shatabdi (V1 ) also showed high ear bearing tillers, 1000-grain weight, total dry matter, crop growth rate. And relative growth rate and leaf weight ratio. It was suggested that for better yield of wheat, variety Shatabdi (V1) should be sown within the third week of November with irrigation in the wheat growing area, especially in the northern region of Bangladesh.