Abstract
In view of the expected increase in drought periods, researchers and breeders are searching for forage grasses that are more tolerant to drought stress. This study wanted to examine the physiological and biochemical reactions of nine forage grass varieties belonging to Festuca, Lolium and Festulolium under mild drought stress conditions in a semi-controlled field experiment. A mild drought stress treatment was applied in the period between cut II and cut III using three large mobile rain-out shelters equipped with sprinkler irrigation systems. The experiment consisted of two soil moisture treatments: (1) control where a soil moisture level of around 20% v/v was maintained and (2) drought stress where the soil moisture level decreased to 7.5% v/v. The experiment was cut 5 times in 2014 and 4 times in 2015. A total of nine varieties from five species of forage grasses were evaluated: L. perenne, L. multiflorum, F. pratensis, F. arundinacea and F. braunii. Dry matter yield, gas exchange parameters and chlorophyll fluorescence were significantly lower in drought stress than under control conditions and the physiological parameters reacted within 2 weeks after the start of the drought treatment in all species. In contrast, drought stress significantly increased water use efficiency, the content of proline, phenolic acids, flavonoids, water soluble carbohydrates and decreased neutral and acid detergent fibre on both years. Based on total dry matter yield and tolerance indices the most drought tolerant species were L. multiflorum in the first and F. arundinacea in the second investigated year.
Highlights
Increased frequency and intensity of drought events are among the main effects of climate change and global warming
Our results showed a significant reduction of dry matter yield in Festuca, Lolium and Festulolium in the field experiment, confirming the results of other authors in many grass species like F. arundinacea, Poa pratensis, Phleum pratense, Phalaris canariensis (Kallida et al 2008; Turner et al 2012)
Our study showed the highest decrease of acid detergent fibre (ADF) in F. pratensis and NDF in L. perenne in both years
Summary
Increased frequency and intensity of drought events are among the main effects of climate change and global warming. Water deficit mainly causes reduced crop yields and inhibits their development, which is related to series of morphological, physiological and biochemical changes in plant tissue. The loss of yield and survival of crop plants depends on duration and intensity of water stress (Bahrani et al 2010; Abbasi et al 2014). One of the most important forage grass species in Northwestern Europe, is susceptible to drought stress and the increase in drought periods triggered researchers to find out the responses of species and varieties of forage grasses to water deficit. The knowledge of tolerance strategies to changing water availability makes a targeted selection of drought tolerant genotypes possible. The Stress Tolerance Index (STI) is one of the most useful indices to recognize tolerant genotypes (Fernandez 1992)
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