Asmare Atalay, P.O. Box 9061, Virginia State University, Petersburg, VA and Francoise D. Favi, Agricultural Research Station, Virginia State University, Petersburg, VA
Salt Tolerance of Mycorrhizal Sweet Sorghum
The term mycorrhizae signifies the symbiotic relationship that exists between higher plants and soil fungi. The association is species specific and non-virulent to the plant. Two types of mycorrhizae are known: endo-type and ecto-type. In endomycorrhizae, the fungus penetrates the cortical cells of the plant whereas in ectomycorrhizae the fungs does not penetrate the cells; however, it forms a Hartig net around the site of infection. During the symbiosis, the plant provides the fungus with sugars, and the fungus assists with nutrients and water from the soil using its hyphae. The purpose of this study is to investigate the existence of symbiosis between sweet sorghum and mycorrhizal fungi, and to examine the significance of the association in salt tolerance of sorghum. Five sorghum varieties: Della, Dale, M18E, Sugar drip, and Keller were treated with an inoculum blend containing eight known fungi. A randomized complete block design with four replications and a control was used in a greenhouse. The growth medium was a mixture of perlite and vermiculite. One scoop (approx. 50 g) of a mix inoculum was added to each pot through the top cut end of a one milliliter Ependorf pipet. Sorghum seeds were germinated inside the pipet and allowed to grow into the pot. A modified Hoagland Solution was applied as needed to keep the growth medium moist and supply nutrients. Salt levels were 0, 10, 20, 40 and 80 mM NaCl solution which were added with the fertilizer. At the end of two months, growth patterns of mycorrhizal and non-mycorrhizal sorghum roots and tops were assessed. Results indicated that higher salt levels (40 and 80 mM NaCl) combined with mycorrhizal fungi had a growth stimulating effect on sweet sorghum. Therefore mycorrhizal sorghum may serve as alternate crop to rehabilitate salt-affected soils.