Evaluation of advantage, competition and radiation interception and use efficiency of summer savory (Satureja hortensis L.) and Persian clover (Trifolium resupinatum L.) intercropping in Mashhad region in Iran

To evaluate advantage, competition and radiation interception and use efficiency in summer savory- Persian clover intercropping as affected by plant density of summer savory under Mashhad conditions in Iran, an experiment was conducted using randomized complete block design with three replications and seven treatments. Treatments were intercropping of Persian clover with 80 plants.m-2 and summer savory with 27, 40 and 80 plants.m-2 and sole cropping of both crops with abovementioned densities. Results showed that Area Time Equivalent Ratio in all intercropping treatments were more than one. Radiation use efficiency (RUE) of summer savory in sole cropping was between 1.32- 1.70 g.Mj-1, and it was higher in intercropping than sole cropping (between 2.60- 2.98 g.Mj-1). The highest RUE of summer savory was obtained in intercropping of summer savory with 27 plant.m-2 and Persian clover. However, in sole cropping treatments by increasing plant density from 27 to 80 plants.m-2 cumulative intercepted photosynthetic active radiation increased but dry matter decreased and RUE reduced. RUE of Persian clover, in all harvests, was greater in intercropping than sole cropping. In the first harvest of Persian clover that had the longest growth duration (116 days), the highest RUE was obtained in intercropping of summer savory with 27 plants.m-2 and Persian clover. In this treatment increasein dry matter of Persian clover was higher than increase in intercepted photosynthetic active radiation of Persian clover. Therefore, this treatment was identified as suitable intercropping plant density considering RUE, Area Time Equivalent Ratio and Economic value.