Modelling the Effect of Seedling Culture on Yield and Water Use of Maize under Gorgan Environmental Conditions

Introduction[1] Method include seedling size and planting date. Since field experiments are usually laborious and costly, the simulation models could be used as a useful tool for investigating such factors. Due to climate change affects the outputs of crop models, the crop growth simulation models should be widely evaluated with empirical data to ensure that simulation of crop growth under a different management strategy or future weather conditions is reliable. Martials and Methods In the present study, the effect of direct-seeding and four seedling sizes (13, 16, 19 and 22 leaf area cm2plant-1 and at 200, 250, 300 and 350 °C cumulative temperature) for transplanting method at four planting dates (10 June, 25 June, 14 July, and 27 July) was simulated in Gorgan environmental conditions for 16 years (2000-2015) using SSM-iCrop2 model. In this simulation, it was supposed that the corn should be harvested on 22 November to provide sufficient time for cultivating the next crop. Also, the economic evaluation between the two methods of transplanting and direct-seeding was carried out using a questionnaire from farmers and experts in the field to evaluate the costs of these two methods . Results and Discussion The simulation results showed that at early planting date (10 June), in transplanting method, the crop matured earlier between 16 to 26 days compared to the direct-seeding, depending on seedling size. In addition, the average yield of 1331 g m-2 and average net irrigation requirement of 435 mm ha-1 were obtained. At this planting date, transplanting had no effect on the yield and net irrigation requirement. In the common sowing date (25 June), the crop matured earlier between 19 to 33 days (early harvest) in the transplanting method compared to direct-seeding, however, the planting method had no effect on the yield and net amount of irrigation. At this planting date, the average yield and water requirement were 1329 g m2 and 416 mm ha-1, respectively. In late planting date (14 July), transplanting with large seedlings (leaf area of 19 and 22 cm2 plant-1) were able to complete their growth period before 22 November. Average yield and irrigation requirement were 1273 g m-2 and 381 mm ha-1, respectively. It should be noted that in late planting date, direct-seeding and transplanting with small seedlings (leaf area of 13 and 16 cm2 plant-1) were not able to complete maturity to 22 November, therefore, this planting date is not recommended. At the last planting date (27 July), all types of cultivation are not recommended as crop growth period are not completed before 22 November. Conclusion In general, it can be concluded that transplanting method would be only recommended for late planting date with using large transplants (leaf area of 19 and 22 cm2 plant-1). However, transplanting did not significantly decrease the amount of net irrigation requirement at any of the planting dates, and also had higher costs and lower profit.