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Growth and water use were studied in contrasting populations (pops) of M. sativa L. adapted to Mediterranean areas: CUF-101, an erected high yielding variety of oasis type; Melissa and Cinna, two French Mediterranean, erected and high yielding varieties; Coussouls, a French, semi-prostrate and grazing tolerant variety; ES-96 and Gazon, two creeping germplasm selected in wild spanish material. Pops were grown in big pots (20 l, 4 plants per pot) under a rainout shelter and studied along their 3rd and 4th cycles in summer, under five contrasting evapotranspiration rates (ET) created by five daily levels of water supply (Wn) by underground drip. Each pot was regarded as a lysimeter plot (accurate measurements of water supply, leaching, weight variations) to calculate ET through water balance. Biomass production (DM) during the period was measured in three fractions (forage, crowns, taproots). Results show significant effects of Wn and pops (p<0.001) on the growth of all fractions, without significant interaction pops × Wn. Erected types had the highest forage yields and root growth, even at the lowest Wn. In each pop, DM increases of the three fractions and of the whole plants were highly correlated with the total ET of the two cycles (all r coefficients between 0.97 and 0.996, p<0.001). The slope of the regression line representing total DM of each pop as a function of ET is an expression of its WUE in these conditions. Expressed as g DM.kg-1H2O, it was significantly different between three groups, ranking from 2.7 (Cuf-101, Melissa, Cinna) to 2.2 (Coussouls) and 1.3-1.5 (E96, Gazon). At this stage of plants and season (late summer), allocation to roots and crown was more than half of DM, higher in Gazon than others. It is concluded that in breeding programs using creeping alfalfa types for Mediterranean areas, attention must be given to WUE.
biomass production, crop yield, cultivars, dry matter,growth, lucerne, plant water relations, roots, water use, water useefficiency, Medicago, Medicago sativa, Medicago, Papilionoideae,Fabaceae, Fabales, dicotyledons, angiosperms, Spermatophyta, plants,eukaryotes, alfalfa, cultivated varieties, Forage and Fodder Crops(FF007) (New March 2000), Plant Breeding and Genetics (FF020), PlantWater Relations (FF062), Plant Production (FF100)