determination of planting date and supplemental irrigation for rainfed lentil in qazvin plain by computerized model

planting at the right time and supplemental irrigation are considered as the effective management practices in increasing rain productivity and rainfed lentil yield and have been discussed in several studies. in this study, the suitable planting date and supplemental irrigation time for lentil in qazvin weather conditions were examined in a computerized model. in this model, soil water content and water requirement of lentil crop were calculated by meteorological and geographic data, information of slightly soil and plant and according to fao relations and then were compared. finally, the planting date with the least amount of stress to the plant during the growth period and sensitive stages was identified as the most suitable planting date. the time of supplemental irrigation also was determined in order to minimize the amount of stress to the plant in the intermediate stage of growth. based on the results of the model among the planting dates (march, 15th; march, 24th; april, 3th and april, 13th) the suitable planting time for spring lentil was march, 15th from the review times and the suitable time for supplemental irrigation was 10-15 days after the start of the sensitive growth stage (intermediate stage).