Enhanced Irrigated Canola Seedling Emergence with Longitudinal Cracks along Seed Rows from a Furrow Opener and Press Wheel

Poor stand establishment of canola (Brassica napus L.) under flatland mechanizedplanting and crust-forming soil is a major problem for farmers in central Iran.Previous research there showed that irrigated cotton emergence on crust-forming soilsunder flatland planting can be significantly improved using a double-disk planter withzero-pressure press wheel tires and no crust-breaking. In that research, it was not clearwhether the furrow opener or the press wheel caused the development of the crackline along the seed rows. In the present study, field testing was conducted in loamysoil to study the effects of two furrow openers (runner, double-disk) and four presswheels (zero-pressure pneumatic, V-shaped edge, single conical rib, open-centerconcave steel press wheels) on canola emergence using a randomized complete blockdesign in a factorial arrangement (2×4) with four replications. Effective crack (crackline developed along emerging seedlings) percentage, stand establishment uniformity,percentage of emergence, and plant density before onset of winter were measured.The results showed that, for all parameters, the double-disk opener had significantlyhigher values compared with the runner opener. The press wheel had a significanteffect on the effective crack percentage and the stand establishment uniformity indexbefore the onset of winter. However, the other parameters were not significantlyaffected. Planters with a single-conical rib and open-center press wheels had the besteffective crack percentage and lowest index of stand establishment uniformity. Basedon the results from this study, the best planter for canola production for the soil andclimate of central Iran is a double-disk planter with a single conical rib and opencenterconcave steel press wheels. The single conical rib creates a v-shapeddepression and the steel press wheels stabilize the depression. This creates a crackalong the deepest line of the depression after flood irrigation and during soilshrinkage, causes creation of crack along the deepest line of depression.