Effects of planting date and plant density on yield and yield components of Brassica nigra under Abarkooh climatic conditions

Abstract
Background and objectives: Black mustard (Brassica nigra (L.) Koch) is an annual plant belongs Brassicaceae. It has a variety of uses in traditional medicine for rheumatic and neurological pain. Growth and development and production of medicinal plants, like other plants is influenced by genetic and environmental factors. Select the most appropriate planting date and the most favorable plant density is an important factor in the success of any plant is cultivated. There is optimal planting date for each plant that the delay is usually reduced its yield. Agronomists believe that the appropriate plant density at the farm is the foundation of a farming system. In appropriate density the plant can use all environmental factors and decreased competition between plants.
Materials and methods: In order to evaluate the effects of sowing date and plant density on yield and yield components of black mustard, an experiment was conducted based on RCBD with three replications at Abarkooh (Yazd Province) during growing season (January-June) at 2012 and the height is 1700 meters above sea level in the region. Treatments were three planting dates (30/Jan, 19/Feb and 11/March/2012) and three plant densities (33, 50 and 100 plant/m2). Following traits were measured: LWP, RWC, plant height, branch/plant, fruit/plant, seed/fruit, 1000-seed weight, seed yield, biological yield, oil percent and oil yield of black mustard. For measuring LWP, had used solutions from sucrose (-5, -10 and -15 bar). Data analyzed by MSTATC and SAS 9.2 and then means compared with LSD.
Results: Results showed there is significant difference between planting dates on RWC, plant height, branch/plant, fruit/plant, seed/fruit, 1000-seed weight, seed yield and biological yield. 30/Jan is the best date with 1474.2 kg/ha (seed yield), 359.34 kg/ha (oil yield) and 8190 kg/ha (biological yield). There is no significant difference among plant densities on biological yield, seed yield and oil yield traits. The interaction effect of planting date and density on the number of silique/plant and the number of seed/silique were significantly different. The effect of plant density on seed yield did not have significant difference. In high density seed yield decreased because of decreasing of branch and silique/plant. There’s no significant difference between plant densities and sowing dates on oil percent.
Conclusion: Results showed that planting dates have strong effect and selected densities have poor effect on yield, in appropriate planting date arise plants with good vegetative growth and ultimately yield well. In general, according to the results of mean comparison of interaction effects of density and planting date on seed yield and oil yield, 30/Jan and 100 plant/m2 in the Abarkooh and similar areas is recommended.