effects of oganic and biofertilizers on growth indices of castor bean (ricinus communis l.)

introduction castor plant, ricinus communis l. is a species of flowering plant in the spurge family; euphorbiaceae, which contains a vast number of plants mostly native to the tropics. it belongs to a monotypic genus ricinus. the name ricinus is a latin word for tick. the plant is probably named because its seed has markings and a dump at the end that resemble certain ticks (ncri, 2014). castorbean is an industrial oil seed crop containing about 45-58 percent oil, which has tremendous application in petrochemicals, pharmaceuticals, cosmetics, textiles, chemicals, soap, leather, paints, varnishes, ink, nylon and plastic. castor oil is traditionally associated with medicine and veterinary use in the fields of obstetrics, dermatology. it is also used as laxative. presently, its utilization as bio-diesel has magnified its importance. its oil does not freeze even at high altitudes and it is one the best lubricants for jet engines. this 100% castor-based product, has numerous applications in industry such as rotating glass car-wipers, ski boots fixatives, and for use in air-brake systems on trucks. many new uses, based on the biodegradability of castor oil derived products, are expected in the future (labalette et al., 1996). the shell of the castor bean is used as an organic termite control agent and its seed cake as manure in the soil. medicinal plants are valuable resources in a wide range of natural resources that scientific identification, cultivation, development and proper utilization of them can have an important role in community health, employment and non-petrol exports. quality of medicinal plants is more important than other crops. one of the most important factors determining the yield of castor bean is fertility. integrated supply of nutrient to plants through combinations of organic and inorganic sources is becoming an increasingly important aspect of environmentally sound agriculture. reports showed that the application of manure on bean has improved yield and growth index. materials and methods in order to study the effects of biofertilizers and vermicompost on the growth indices of castor bean (ricinus communis l.), a field experiment was conducted during the growing season of 2009 at the agricultural research station, college of agriculture, ferdowsi university of mashhad, iran. a randomized complete block design with three replications was used. treatments included: nitroxin biofertilizer, phosphate suloblizing bacteria and vermicompost and control (without any fertilizer). the results indicated that uses of organic and biofertilizer significantly increased plant height, leaf area index (lai), total dry matter (dm), crop growth rate (cgr) compared with control. the areas of green leaves were measured using a delta-t leaf area meter (delta-t devices, cambridge, england). then the samples, including stems and leaves were dried in a forced-air oven at 80 ০c for 48 h and after the witch total dry matter (tdm) was measured. the leaf area data were divided into ground area and the leaf area index (lai) was obtained. the lai data were fitted to the gaussian equation to predict the lai of common bean in growth season. the sigmoid equation was fitted to the tdm data and by derivation from this equation, the crop growth rate (cgr) and relative growth rate were obtained. the analysis was performed using sas 9.1 and the graphs were prepared using excel. results and discussion the study results indicated that uses of organic and biofertilizer significantly increased plant height, leaf area index (lai), total dry matter (dm) and crop growth rate (cgr) compared to control. the highest and lowest leaf area index was observed in vermicompost (2.15) and control (0.88) treatments, respectively. the maximum and the minimum amounts of dry matter were recorded in the vermicompost treatment with 693.32 g.m-2 and control with 495 g.m-2, respectively. crop growth rate reached to its peak in 85 days after emergence, the height and the lowest was observed in the vermicompost treatment with 16.45 g.m-2.d-1 and control with 7.63 g.m-2.d-1, respectively. assimilation rate also reached to its maximum and minimum in vermicompost treatment (17.31 g.m-2.d-1) and control (10.91 g.m-2.d-1), respectively. conclusion the results showed that integrated biofertilizer and vermicompost are good choices for decreasing chemical fertilization application.