effects of various organic and chemical fertilizers on growth indices of basil (ocimum basilicum l.)

in order to develop the high intensive agriculture, more chemical fertilizers are applied to the soil that resulting in soil degradation and environment deterioration. application of organic manure is an important approach for maintaining and improving the soil fertility and increasing fertilizer use efficiency. therefore, in order to evaluate the effect of organic manures and chemical fertilizer on growth indices and biological yield of basil (ocimum basilicum l.), an experiment was conducted at research station, faculty of agriculture, ferdowsi university of mashhad, iran, during growing season of 2008-2009. a complete randomized block design with six treatments and three replications was used. the treatments were: cow manure, sheep manure, chicken manure, vermicompost, chemical npk fertilizers and control (no fertilizer). the results showed that the use of organic fertilizers significantly increased seed and biological yield of basil compared with chemical fertilizer and control. the maximum and the minimum dry weights were observed at 105 days after planting, in sheep and cow manures, respectively. gradually during the period of plant growth and development to reproduction phase percent of stem decreased and dry weight of inflorescence increased. the highest and the lowest leaf area index were observed at 90 days after planting, in cow manure and control, respectively, and then decreased in all treatments. the maximum crop growth rate in most of treatments at 90 days after planting was obtained, except the control which plant growth rate was lowest. net assimilation rate (nar) in most treatments increased until 75 days after planting and then declined. while the highest and the lowest nar were observed at 75 days after planting in chicken manure and chemical treatment, respectively.