The major diseases associated with Safflower and some of the resistant sources

Abstract

Safflower, Carthamus tinctorius L., is an annual, broad leaf crop which belongs to the family of Compositeae. Safflower is cultivated worldwide as an oilseed or ornamental crop. In Iran, this crop is grown for its seeds to extract oil or feed home birds, and also for its flowers to use in medicine or ornamental purposes, and is being cultivated on approximately 1000 ha annually.1 Safflower (Carthamus tinctorius L.) is an oilseed crop of increasing importance in the world. This crop has been grown for its flowers for many years in Iran, which is one of the centers of safflower culture in the old world.2 In recent years due to an parts, reduced seed sizes usually occur. Disease incidence and severity are often greatest when maturing increasing demand for vegetable oil for the human uses, its production as an oilseed crop has received a great deal of attention. Growth of the crop is severely affected by many seed, soil and air borne fungal diseases such as Fusarium and Verticillium wilt, Phythophthora and stem rot, rust, and Alternaria leaf spot. They are namely as; Alternaria alternat, A. carthani, Bremia lactuca, Cochlioblus sativus, Fusarium culmarum, F.oxysporum, Gibberella acuminate (Fusarium acuminate), G. intercans (Fusarium equiseti), Golovinomyces cichoracearum (Erysiple cichoracearum), Leveilla taurica, Macrophomina phaseolina, Nectria haematococca (Fusarium solani), Phytophthora drechsleri, Puccinia carthami, Pythium oliganderum, P. ultimum, Ramularia cynarae (R. carthami and or Cercospora carthami)Sclerotinia,sclerotiarum, Thanatephorus cucumeries (Rhizoctonia solani) and in case of wild safflower, Leveilla taurica, Puccinia carthami and Ramularia cynarae.3,4 Safflower plants (Carthamus tinctorius L.) with phyllody symptoms were observed by Salehi et al.,5 in Fars and Yazd provinces of Iran. They reported that, affected plants show floral virescence, phyllody and proliferation, proliferation of auxiliary buds along the stem and little leaf symptoms.5 Recently, charcoal rot caused by Macrophomina phaseolina has been considered as a relatively important disease in safflower. The first report of charcoal rot disease on safflower growth in Iran was in northeastern Golestan Province in the summer of 2002.6 M. phaseolina, the causal agent of seedling blight, root rot and charcoal rot of more than 500 crop and non crop species; primarily is a soil-borne fungus.7 Although initial infections occur at the seedling stage, they remain latent until the safflower plant approaches flowering or maturity. The first symptom is general wilting of the plant during the middle of hot days followed by a recovery in the evening as temperature declines. The stems of infected plants eventually take on a gray discoloration at the base and finally, the vascular bundles may become covered with microsclerotia of the fungus. Since charcoal rot restricts the flow of water and nutrients to the upper plants are stressed by drought and high temperature which leads to premature plant death. In some cases, this pathogen kills up to 25% of the plants in commercial fields of safflower.8 Similar to other crops, management strategies to control charcoal rot in safflower including crop rotation, lower plant density and scheduling planting date and irrigation to reduce the effect of mid-season drought stress.7 Planting resistant cultivars is the most permanent and practical way for the control of the disease, because above mentioned strategies fail to provide adequate control. Although, responses of different genotypes to the charcoal rot disease caused by M. phaseolina have been reported many times in other crops such as and soybean9 and alfalfa10 such information are not available in the literature for safflower. Therefore, the objective of this study was to screen some genotypes of safflower under field conditions for resistance to charcoal rot disease. We further report those traits that are correlated to the resistance for indirect selection