Climate, nitrogen and grass : research into the influence of light intensity, temperature, water supply and nitrogen on the production and chemical composition of grass

The investigations referred to indoor and field experiments, carried out with Lolium perenne.

With an increasing light intensity yield of dry matter, the contents of dry matter, water-soluble carbohydrate and 'rest' (residue) increased; those of nitrate, crude protein, ash and crude fibre decreased.

A rising temperature caused some yield increase, dry matter content hardly changed, crude protein and water-soluble carbohydrate diminished and so sometimes did the ash content whereas crude fibre and 'rest' increased.

Water shortage decreased yield of dry matter and increased contents of dry matter, nitrate, crude protein and ash. Water-soluble carbohydrate, crude fibre and rest were usually reduced.

Nitrogen dressing stimulated yield of dry matter, nitrate, crude protein and ash, and sometimes the crude fibre. Contents of dry matter, water-soluble carbohydrate and 'rest' contents decreased.

Light and N both increased yield of dry matter, but counteracted each other in the chemical composition.

Crude fibre and 'rest' in fresh matter were positively correlated with water consumption per g fresh matter. Some informative experiments with Brachiaria ruziziensis gave similar results. It was suggested, therefore, that high temperature, and low nitrogen supply might by the chief explanation for the low nutritive value of grass in the tropics.