Evaluation the effects of manure and mycorrhizal inoculation on grain and oil yield of spring safflower cultivars (Carthamus tinctorius L.)

Considering the nutrient loss, environmental pollution and increase in production costs on account of chemical fertilizer application, supplying mineral nutrients based on organic sources and mycorrhizal inoculation can improve organic matter content in soil (Hallajnia et al., 2007), promote sustainable production of oil crops (Kawthar et al., 2010) and ultimately affect the long term performance of the agricultural ecosystems in arid and semi-arid regions. Safflower (Carthamus tinctorius L.) is an annual oil seed crop belonging to the Asteraceae family and its spring cultivars are mainly grown in semiarid regions, especially in Iran. Hence, the current experiment was aimed to evaluate the effects of manure application and mycorrhizal inoculation on yield and yield components of spring safflower cultivars in Iran. In addition, quality yield in term of oil percentage was studied in response to experimental treatments. A field experiment was conducted at Agricultural Research Station of Ferdowsi University of Mashhad, Iran (latitude: 15° 36´ N, longitude: 28° 59´ E, altitude: 985 m), during growing season of 2009-2010, by using a completely randomized block design based on factorial fraction with three replications and sixteen treatments. The experimental treatments included four spring safflower cultivars (Darab, Isfahan, Arak and IL-111), two manure levels (no applying and applying manure 25 t.ha-1) and two mycorrhiza levels (no inoculation and inoculation with Glomus mosseae). The experimental field was prepared according to the local practices for safflower production. Each plot was 6 m2 (3 m long) and 1 m apart. Between blocks, 2 m alley was kept to eliminate all side effects of treatments. Seed sowing was performed at 14th April in 2010. Final density was 50 plants.m-2. The first irrigation was immediately done after seed sowing with weekly irrigation until physiological maturity stage (10 days before harvesting). At fully blooming stage, plant were harvested in one square meter in each plot and fresh and dry petal yield were recorded. At maturity stage, five plants from each plot were chosen randomly and number of branch per plant, number of seeds per head, seed weight per plant and 1000-seed weight were recorded. Final grain and oil yields were measured by harvesting 1 m2 of the central part of each plot. For statistical analysis, analysis of variance (ANOVA) and Duncan’s multiple range test (DMRT) were performed using SAS ver. 9.1 software. Results indicated that applying manure significantly affected number of branch per plant, number of seed per head, seed weight per head and 1000- seed weight as well as petal, grain, biological and oil yields of safflower cultivars. For instance, the applying manure significantly increased grain and oil yields of safflower cultivars more than two times. As mentioned before, organic fertilizers can improve the organic matter content, aggregates stability and nutrients availability in soil (Khandan & Astaraei, 2005; Halajnia et al., 2007), so application of manure fertilizer and gradual release of mineral nutrients into the soil would increase the growth, production and quality yield of spring safflower cultivars. Based on the results, effects of mycorrhiza inoculation on increasing the number of seed per plant, 1000 seed weight, petal, grain, biological and oil yields of safflower were significant. The highest grain (2546 kg.ha-1) and oil yields (685 kg.ha-1) were obtained from manure + mycorrhiza inoculation treatment. However, manure + mycorrhiza inoculation treatment did not have any effect on oil percentage and harvest index. Effective role of mycorrhizal inoculation in increasing the grain yield of safflower has also been reported by (Mirza Khani et al., 2010). Among safflower cultivars, Darab cultivar indicated the highest grain and oil yields (1327.7 and 346.4 kg.ha1, respectively). Based on our results, Darab and IL-111 cultivars had the most grain and oil yields, in comparison with Isfahan and Arak cultivars. However, no significant difference was observed between the spring safflower cultivars in term of number of seed per head and oil percentage. Consequently, selecting the Darab cultivar and applying manure in combination with mycorrhizal inoculation is strongly recommended to achieve a reasonable and stable yield of safflower. However, the environmental conditions of the cultivated area should be specifically considered to select a spring safflower cultivar.