Reaction of Some Soybean Seed Coat Colors to Rhizoctonia Root Rot and Other Damping – Off Disease Agents, Yield and Yield Components

Abstract

Laboratory, pot and field experiments using two soybean cultivars had yellow colored seed coats namely Giza 111 and Toano in addition to two promising breeding genotypes had black and brown colored seed coats; naturally mutated from Toano[ NMT] (black) and L159 L2 (brown), were carried out during two successive seasons 2014 and 2015 at Etay El-Baroud Agricultural Research Station, El-Beheira Governorate. Data of the laboratory experiment showed that there is a reversible relationship between seed coat extract concentrations, and Rhizoctonia solani growth diameter after 4 days, since the reduction was 18.89, 45.22 and 50.78% for the concentrations of 25, 50 and 75%, respectively for the black seed coat extract. In case of the brown seed coat extract concentrations, the same trend cleared where the fungal growth reductions were 22.56, 28.11 and 31.44%, respectively. The least reduction effect was observed with the yellow seed coat extract, where it was 11.44, 19.67 and 25.22% with the same concentrations mentioned above, respectively. Results of pot experiment showed that pre-emergence damping-off caused by R. solani was the least with the seedlings of black seed coat (NMT), followed by that of brown seed coat (L159 L2) and finally with that had yellow seed coat (Toano) with averages of 22.00, 23.35 and 26.77%, respectively. Removing seed coats (uncoated seeds) increased pre-emergence damping-off to 46.67, 50.00 and 66.67%, respectively. Also, disease severity showed the same trend with coated and uncoated colored seed coat genotypes. Under field conditions, at the first season the least pre-emergence damping-off was observed with Toano (yellow) followed by L159 L2 (brown), NMT (black) and Giza 111 (yellow) with averages of 15.67, 21.33, 29.00 and 32.00%, respectively. The same trend cleared in case of the post-emergence damping-off, where Toano had the least value followed by L159 L2, NMT and Giza 111 with averages of 4.35, 6.33, 6.61 and 12.68%, respectively. Data of the second season was parallel with that of the first one but with light differences in the arrangement. Soybean seed yield components at the first season showed that Giza 111 had the highest values in case of the number of pods/plant, number of seeds/plant, seed weight/plant (g), 100 seed weight (g), seed yield/plot (kg) and seed yield /feddan (ton) followed by L159 L2 and NMT, respectively. Also, data obtained in the second season were closed with that of the first season.