Comparision of Production and N Concentration of Indian-Origin Guar (Cyanoposis tetragonoloba) Lines in Oklahoma.

The warm-season pulse guar (Cyanoposis tetragonoloba) has potential to provide alternative crops for the southern Great Plains (SGP). This study evaluated the potential of 3 Indian-origin lines of guar for forage and grain production in Oklahoma, and nitrogen (N) concentrations of biomass. Replicate (n=3) plots (30 m²) were disked, fertilized (60 kg ha^-1 P₂O₅), and sown (25 kg ha^-1; 60 cm rows) with inoculated Bundel (BG) lines BG-1, BG-2, and BG-3 lines, and Kinman (control) late-May 2009 through 2011. Plant samples were collected at vegetative (leaf+stem) and physiological maturity stages, with samples collected at maturity separated into leaf+stem, pods, and grain portions. Samples were dried to constant weight (60°C forced draft oven) to calculate aboveground biomass, and analyzed for N concentration. Biomass yield and N concentrations showed significant year X growth stage interactions (p≤0.01); no effects related to cultivars were recorded in herbage production (0.46<p<0.34). Significant cultivar and year effects (p<0.05) were recorded in grain yield, as were year effects (p<0.01) on N concentration. Significant year effects were noted in pod (Chaff) biomass, and cultivar x year interactions (p=0.01) in N concentrations of pods. The primary cultivar effects were lower grain yields and higher N concentrations in pods of the 3 Indian lines compared to the control. However, the primary driver of responses was factors related to time of growing season and individual growing seasons. Results suggest research on additional lines of forage guar will be required to identify more effective plant materials for the variable environments of the SGP.