Influence of nitrogen and biological stimulants on growth, nutritive value, and salt stress tolerance of 'Matua' and 'Gala' bromegrasses
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'Matua' {Bromiis willdenowii Kunth ) and 'Gala' Bromus siamineus Des) bromegrasses have potential in West Texas but little information exists on their adaptation. Field and greenhouse experiments were conducted to determine seasonal yield, forage quality. N response, and salinity tolerance. Gala and Matua were compared to double-cropped 'TX 91 V 4511' wheat (Triticum aestivum L .)-foxtail millet (Setaria italica (L.) Beauv.) in a randomized block design with four replications in the field. Forages were sampled monthly from 15 November, 1996 to 21 December, 1997, and forage mass, fiber components, crude protein (CP), total nonstructural carbohydrates (TNC), and NO3 were determined. Forage mass of bromegrasses was lower (P<0 05) than wheat during winter and spring and than millet during summer. At first hay harvest, Matua was similar to wheat in yield (8,434, 8,172, and 6,827 kg ha"' for Matua, wheat, and Gala, respectively). Matua was higher (P<0.05) in TNC and lower (P<0.05) in CP than Gala. Delaying harvest decreased (P<0.05) forage quality in Matua more than Gala Matua and Gala were established in the greenhouse and were watered with Hoagland's nutrient solution for three completely randomized design experiments with four replications. Calcium and sodium chloride were added (2:1 ratio) to provide a range in EC from 2-12 dS m' (2-6 dS m"' for Gala). After 5 wk, plants were harvested to determine dry weight of roots and shoots. A 50% yield reduction for Matua and Gala was observed at 6 and 5 dS m"', respectively. Adding 4 kg Ascophyllum nodosum ha"' plus 24 kg S ha"' increased (P<0.05) both root and shoot dry weights compared to controls or either substance alone. Nitrogen fertilizer was applied at 50, 100, 200, 300, and 400 kg N ha"' at each of five harvests of Gala and Matua. At 50 kg N ha"', over 80% ofthe total 250 kg N applied was recovered. Nitrogen use efficiency and N recovery decreased quadratically (P<0.05) in both species with increasing N rates. Nitrates in soils and plants increased quadratically (P<0.05) for both species and reached levels of concern to animal health and to the environment for rates over 50 kg N ha'' per application.