Dehydration tolerance and drought survival summer dormant Moroccan ecotypes cocksfoot (Dactylis glomerata L.)
2012
R., Kallida | N., Shaimi | F., Volaire
Summer dormancy in perennial grasses is a major trait conferring plant survival and persistence in Mediterranean areas. The aim of the present study was to characterize the effect of summer dormancy on dehydration tolerance in six Moroccan ecotypes and two cultivars “Kasbah” and “Porto” of Dactylis glomerata in a glasshouse experiment. Measurements included the ratio of green-senescent aerial tissues, soil water evolution, water content in survival organs and plant survival rate. D8 and D9 ecotypes showed high senescence when soil moisture was 5 per cent, while Kasbah (dormant cultivar) was at 52 per cent of areal senescence. Proportion of senescent tissue reached 98 per cent for all ecotypes at soil humidity of 1.9 per cent. Under severe drought, water content of apices decreased to reach 0.31 g H20 g–1 dry weight, which was a lethal value for four tested ecotypes and cv. Porto. Except for Kasbah, D1 and D6, which remained alive with little hydrated apices. The soil moisture associated with 50 per cent of plant mortality was 2.5 per cent for Porto and D8 but decreased to 1.9 per cent for D14. Kasbah, D1 and D6 could survive until 1 per cent soil moisture. These results are ascribed to efficient strategies of both dehydration avoidance and tolerance in the best surviving genotypes.
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