Efficiency Test of Sinorhizobium fredii Local Isolate Biofertilizer on Growth and Yield of Cowpea Vigna unguiculata L.

(Wael. M. Mahdi and A. E. S. Alkurtany)

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Abstract

Legumes' treatment with efficient inoculant is an important economic practice regarding nodules formation, increasing production, and improving soil fertility and productivity. Laboratory and field experiments were conducted to prepare an ecologically safe fertilizer to improve the growth and yield of cowpea using Sinorhizobium fredii isolated from 46 legumes roots and soil samples collected from various agricultural areas of Iraq. The isolate was prepared by growing the samples on yeast extract mannitol agar (YEMA). It was identified using culture and microscopic characteristics, biochemical and physiological test, and PCR technology. A split plot experiment was conducted in sterile and non-sterile soil. The results showed a significant increase in the studied characteristics of cowpea due to biofertilizer treatments. The percentages of number of nodules and dry weight of biofertilized plants increased by 193.49 %, 375.00 %, respectively. Root and shoot dry weight increased 122.45 % and 148.34 %, due to biofertilizer treatment compared to non-fertilized ones. The results also showed a significant increase in the number of pods, total yield, and the ratio of protein in seeds by 68.47 %, 225.76 %, and 22.29 % respectively. The differences in growth and yield characteristics due to sterilization were insignificant compared to non-sterile except for nodules weight per dry root produced from non-sterilized treatments, which was significantly higher. The interaction between fertilization and sterilization showed that the fertilized and sterilized treatment combination was significantly higher compared to non-fertilized and sterilized treatment in all studied traits. The isolate used was efficient in nodules formation and caused a significant increase in the characteristics of growth and yield. Attention must be given to treat seeds with this type of inoculum as well as testing other isolates that are characterized by high efficiency in causing nodulation and competing with local bacteria. Key Words: Inoculation, Legumes, Rhizobium, Sterilization.
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