CHARACTERIZATION OF BROOM SORGHUM ACCESSIONS USING MORPHO-AGRONOMIC DESCRIPTORS

The straw broom production is a traditional and very old activityamong small farmers in Brazil. Much of the straw broom production ismanufactured with native species, which in turn are in the process of beingextinct. The objective of this work was to evaluate the genetic diversity andto characterize one sample of broom sorghum germplasm constituted of 66accessions. The experiment was carried out in Viçosa, MG, in a randomizedblock design with two replicates, being each plot composed of one 5 m row,with 0.7 m spacing, where eight morpho-agronomic traits were evaluated.The studied accessions presented genetic variability for most of the traits.The accessions 2, 7 and 16 presented the lowest plant heights. Regardingstem diameter, accessions 7, 11, and 13 presented the highest values. Asto the number of days from emergence to flowering, the accessions 42, 65,and 66 were the earliest ones. Based on the evaluations carried out, it can beconcluded that accessions 2, 7, 11, 13, 42, 65, and 66 are the most promisingfor new studies and launches.

Screening of Organic Substrates for Solid-State Fermentation, Viability and Bioefficacy of Trichoderma harzianum AS12-2, a Biocontrol Strain Against Rice Sheath Blight Disease

The present study was undertaken to find the most suitable organic substrates for the biomass production, viability and efficacy of the biocontrol strain Trichoderma harzianum AS12-2 in the solid-state fermentation system. In total, 13 inexpensive, locally available substrates (agricultural wastes or by-products) were inoculated with the antagonist, and following one month of incubation at room temperature, all colonized substrates were air dried and ground to powder. The shelf life and viability of the Trichoderma strain were assessed as colony-forming units per gram (CFUs g−1) of each substrate on a monthly basis for up to one year at room temperature (25 ± 2 °C) and in the refrigerator (4 °C). In order to find out the effect of the substrate on the bioefficacy of T. harzianum AS12-2, the biocontrol potential of the formulations was evaluated against rice sheath blight disease caused by Rhizoctonia solani. The results showed that the fungus colonized more or less all substrates after one month, although the degree of colonization and conidiation was different among the substrates, being especially high in broom sorghum grain, rice husk, rice straw, rice bran and sugar beet pulp. Analysis of variance (ANOVA) of the population in the substrates in “Month 0” showed that the effect of treatment was significant, and the means were significantly different. The maximum population was recorded for broom sorghum grain and rice straw (6.4 × 1010 and 5.3 × 1010 CFUs g−1, respectively). The population declined in all substrates after one year of incubation at room temperature. This decline was relatively smaller in broom sorghum grain, rice straw and rice husk. On the other hand, the population in the same substrate incubated in the refrigerator was decreased in a mild slope, and the final population was high. In addition, the results of greenhouse assay showed that all bioformulations were effective in controlling the disease, and there were no significant differences among the substrates. According to the results of this study, broom sorghum grain, rice husk, rice straw, sugar beet pulp and cow dung could be recommended as suitable fermentation media for the industrial-scale production of T. harzianum strains.

Biological control of rice sheath blight disease with formulation of indigenous Trichoderma strains under paddy field conditions

The effectiveness of indigenous Trichoderma strains in preventing sheath blight disease was evaluated during two growing seasons under paddy field conditions. Broom sorghum seeds were used for mass production of Trichoderma strains. Colonized seeds were ground to powder and mixed with talc and carboxymethyl cellulose. Suspensions were made from the bioformulations and sprayed onto rice plants. Effects of Trichoderma strains on disease incidence and severity as well as yield and other growth parameters were determined and compared with a chemical fungicide and a commercial biofungicide. A combined analysis of variance across two years was performed and a statistically significant effect of year, treatment and their interaction was reported. Results indicate that environmental factors and different biological fungicides had a strong effect on disease development under natural conditions. According to the results, propiconazole and T. harzianum AS12-2 resulted in the least disease severity and incidence. Overall, the efficacy of T. harzianum AS12-2 in reducing sheath blight development was significantly better than other Trichoderma treatments and was comparable to the conventional fungicide.

Evaluation of microwave irradiation effects on nutritive value of broom sorghum grain using an in vitro gas production technique

In Iran various varieties of sorghum (Sorghum vulgare) are planted mainly for broom production but also for use in animal nutrition. There appears to be no documented research about nutritive value of microwave processed sorghum grain. With microwave irradiation, heat is generated throughout the material, leading to faster heating rates and shorter processing times compared to conventional heating, where heat is usually transferred from the surface to the interior (Fakhouri and Ramaswamy, 1993). In the in vitro gas production method for predicting nutritive value, the kinetics of fermentation can be studied on a single sample and therefore a relatively small amount of sample is required or a larger number of samples can be evaluated at any one time. Gas production measurement provides useful data on digestion kinetics of both soluble and insoluble fractions of feedstuffs (Getachew et al., 1998). The purpose of this study was to evaluate effects of microwave irradiation on nutritive value of broom sorghum grain using the in vitro gas production technique.