Climate, nitrogen and grass. 7. Comparison of production and chemical composition of Brachiaria ruziziensis and Setaria sphacelata grown at different temperatures.

Abstract

7. In order to test the validity of previous results, a trial was performed in greenhouses on the effect of temperature, age and N level on production, morphological and chemical composition of Brachiaria ruziziensis Germain & Evrard and Setaria sphacelata (Schum) Stapf & Hubbard. The 2 grasses were equally productive, but Setaria had a lower optimum temperature. Brachiaria was leafier than Setaria and had higher contents of nitrate and protein; it was also more digestible. It had higher contents of cations, inorganic anions and organic acids, but its oxalate content was lower both in leaves and in stems. Leaves of Brachiaria were much richer in nitrate than those of Setaria at the same protein content. At a greater age, both grasses had higher yields that originated from a greater number of heavier tillers. Plants were less leafy; nitrate and protein contents, and digestibility of organic matter were lower, but percentage of cell-wall constituents was higher. Increase of temperature stimulated plant development in both grasses, causing lower protein content and lower digestibility of organic matter in leaves and stems. Temperature also had a direct negative effect on stem digestibility apart from its effect on stem development. N application increased production, nitrate and protein content in both grasses, but had hardly any effect on plant development and digestibility. Consequently, Setaria reacted to environmental conditions like the other tropical grasses studied in this and previous trials, so confirming the conclusions. (Abstract retrieved from CAB Abstracts by CABI’s permission)