Physiological responses of the green manure, vicia sativa, to drought

Cover crops and green manures have been adopted in rainfed agriculture for providing soil protection between cultivation seasons and for increasing soil nutrient and organic matter content. A greenhouse experiment was conducted to evaluate physiological responses of the green manure Vicia sativa to drought. The gravimetric leaf water of content of 80%25 did not decrease during 24 days of water withholding. Gas exchange was very sensitive to drought. For instance, net CO2 uptake of 7.8 ± 0.17 μmol m-2 s-1 started decreasing at eight days of water withholding but recovered when the plants were re-watered. While total chlorophyll was not significantly degraded for the droughted plants, these individuals accumulated 1,000-fold the proline of the control, which amounted to 0.41 ± 0.09 μmol g-1. Raman spectroscopy revealed differences in the accumulation of metabolites at 24 days of water withholding between well-watered and droughted plants, including a higher content of abscisic acid, gibberellic acid, indoleacetic acid, and zeatin. Vicia sativa can tolerate month-long droughts and can be considered as a useful alternative for increasingly arid locations.

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