عنوان مقاله [English]
Introduction Wheat is the main food commodity of Iranian population and major cultivating crop, grown on nearly half of the country’s rain-fed area as well as one-third of the irrigated area. Despite the availability of high yielding cultivars for different climates, the average wheat grain yield in the country is around 3527 kg ha-1. Lower wheat grain yield could be due to unavailability of recommended varieties seed, delay in planting, inappropriate planting methods, excess use of fertilizers and inefficient water management. Irrigated wheat production in arid and semi-arid regions of Iran is generally practiced under conventional tillage systems. Crop producers in southwestern part of Iran are traditionally using conventional tillage (plowing with moldboard plow followed by double disking) for cultivating various crops. Most of the farmers use grain drills for sowing wheat because of uniformity of planting depth as compared to seed spreaders. The aims of the study were to determine whether different methods of sowing, such as grain drills (followed by flooding irrigation), row crop planting, and combination of furrowers (75 and 60 cm) and seeders (12 cm of sowing space) alter the agronomic performance of winter wheat. Therefore, selection of suitable sowing method plays an important role in the placement of seed at proper depth, which ensures better emergence and subsequent crop growth.
Material and methods The study was conducted on a silt clay loam soil (Carbonatic Typic Torrifluvent) in research farms of Ramin Agriculture and Natural Resources University, Ahvaz, Iran, with wheat-wheat- corn crop rotation. The soil was representative of a large area of arable land in the Khuzestan province. Conventional tillage was practiced by moldboard plow ( 25 cm depth) followed by disc harrow twice (nearly 10 cm depth). The two year experiment was conducted based on completely randomized block design in four replicates. 140 kg/ha of wheat (Triticum aestivum L), Chenab cultivar was sown at 50 mm depth for all treatments. The experimental treatments were 20 furrow opener rain drill with 12 cm line space (P), combination of grain drill-furrower (PF60 and PF75) with 60 and 75 cm furrow spaces, also furrower-grain drill (FP60 and FP75 cm) and furrower –grain drill with 3 planted rows on beds (FP3_60 and FP3_75 cm). Soil conductivity of the experimental field (plots) ranged from 1.2 to 3.3 ds mG. The soil texture was silty clay loam with the range of clay content from 34 to36%, and N, P and K contents of the soil were 0.8 to 1, 6.1 to 16.2 and 117 to 192 mg kgG, respectively.
Results and discussion Wheat grain yield obtained from all treatments was different; however, harvested grain after FP_75 was the highest compared to others. The highest amount of yield was 5966.7 kg/ha for the first year and 5070 kg/ha for the second year compared to simple planting (P) which was the lowest (4883 and 4271 kg/ha respectively for 2 interval years). Analysis of variance for grain yield indicated that FP-75 had a significant difference (p < 0.01) as compared to others, but grain yield for furrow spaces from 60 to 75 cm was not significantly different. However, the use of furrowers showed significant effects on wheat grain yield. Crop yield and biomass were shown to be different where the furrow was made before sowing. The use of grain drills without furrowers had a great negative effect on crop biomass and grain yield. The results obtained from the second year were similar to the first year. The application of furrow before sowing showed maximum crop yield and biomass, so that the highest and the lowest biomass belonged to FP-75 with 14817 kg ha-1 and P with 11731 kg ha-1, respectively. The harvest index was not significantly different among treatments. Similar results were obtained in wheat plots after harvesting.
Conclusion The overall results from this study indicated that the values of crop yield and biomass were maximum where the furrow was made before sowing, as FP-75 treatment had the highest yield. So regarding non-problem of soil salinity in the north of Khuzestan, the use of furrow before sowing can be considered as an appropriate tillage and sowing system for wheat production in the semi-arid region.