Der Einfluß der Wachstumsrate auf die Effizienz des produktiven Wasserverbrauches durch die Kulturpflanze unter Berücksichtigung von C3‐ und C4‐Arten

Abstract

The influence of the growth rate on the water use efficiency by different cultivated plants in consideration of C3‐ and C4‐species The influence of the growth rate (dry matter production per unit of time) on the water use efficiency by different cultivated plants (maize, sunflower, durum wheat, sorghum, amaranthus) was examined using hydroponic culture. The water use efficiency was expressed by the relative water requirement (1 transpirated water per kg produced dry matter), at which the evaporation was absolutely eliminated. The results showed a definite conformity with the hypothesis, which was taken as the basis for these studies: – The relative water requirement was not constant on the basis of the changing growth rate during the course of growth and development of the plants. With increasing growth rate decreased the relative water requirement. The effect of the increasing growth rate on the decrease of the relative water requirement was greater all the more, the more the growth rate increased. – Plants of one and the same species and variety but with different growth rates had different relative water requirements. Those ones with a higher growth rate showed a lower relative water requirement. An influence of the growth rate on the different relative water requirement of C3‐ and C4‐species also was observed. Under better growth conditions for C3‐plants than for C4‐plants, the growth rate of C4‐plants was slowed down, so the relative water requirement was higher than by C3‐species. Concluding from this research, there is the possibility to employ the growth rate of plants for a measure to use water more efficient in plant cultivation.