Expected Economic Potential of Substituting Legumes for Nitrogen in Bermudagrass Pastures

Grazing warm-season grass pastures with stocker cattle (Bos taurus) is an important economic activity in the southern Great Plains, and substantial increases in the price of N fertilizer have negatively affected profi tability of forage producers. The goal of the study was to determine if bermudagrass [Cynodon dactylon (L.) Pers.] pastures interseeded with either annual or perennial legumes are more profitable than the conventional method of fertilizing with 112 kg N ha–1 commercial fertilizer. A completely randomized design grazing study was conducted in south-central Oklahoma during the spring and summer months of 2008, 2009, and 2010. Preconditioned stocker cattle (260 ± 47 kg head–1) were randomly assigned to pastures (1.42 ± 0.10 ha; three replicates per system) at 2.32 ± 0.40 animals ha–1, beginning when measured standing forage reached 2000 kg ha–1 and grazing continuously until forage mass declined to 1000 kg ha–1. Results of the 3-yr grazing study show that under continuous stocking for the growing conditions common to the south-central Great Plains, the legume systems could not compete economically with the common practice of fertilizing bermudagrass pastures with synthetic inorganic N fertilizer. Results are most sensitive to number of grazing days, price of N, and prices of legume seed

Cytogenetic and molecular responses of ammonium sulphate application for tolerance to extreme temperatures in Vicia faba L.

Effects of ammonium sulphate [(NH4)(2)SO4] on mitosis, cell cycle and chromosomes in Vicia faba L. seeds exposed to extreme temperatures were investigated using flowcytometric and cytogenetic analysis. Seeds germinated at high and low temperatures showed a significant decrease in mitotic index as compared to those of optimum temperature conditions. Application of 50 and 1000 mu M (NH4)(2)SO4 were successful in alleviating the negative effects of low and high temperature on mitotic activity, respectively. 50 mu M (NH4)(2)SO4 showed the most positive effect on cell cycle at the extreme temperatures. This concentration increased the cell division removing or decreasing the negative effects of temperature stress. Namely, the highest G2/M and S phase percentages under stress conditions were obtained with application of 50 mu M (NH4)(2)SO4. Chromosomal aberrations were not observed in cells of seeds germinated in distilled water and also at any temperatures. However, the frequency of chromosomal aberrations increased significantly by increasing (NH4)(2)SO4 concentration. The highest aberration frequency in all temperature degree tested was found at 1000 mu M (NH4)(2)SO4 concentration.Department of Scientific Research Project Management of Suleyman Demirel University (SDUBAP)Suleyman Demirel University [1636-YL-08]The authors thank the Department of Scientific Research Project Management of Suleyman Demirel University (SDUBAP) for the financial support of the project SDUBAP (1636-YL-08). Thanks also to Dr. Gulderen Yanikkaya DEMIREL and Mehtap OZDEMIR (Istanbul Centro Laboratory Flowcytometry Department, Istanbul, Turkey) for its help in flow cytometric study