Differential responses of forage legumes to aluminum

Response of alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), and red clover (Trifolium pratense L.) to aluminum was evaluated in a nutrient culture system under controlled conditions. In each of the species, varietal differences were also compared. In the absence of Al stress, varieties of alfalfa and Tensas red clover produced more dry weight than the other legumes. However, among the legumes tested, alfalfa was the most sensitive to Al. Aluminum reduced the uptake of many of essential nutrients. Overall, red clover cultivars experienced the least reduction in elemental uptake, whereas alfalfa cultivars experienced the greatest reduction in uptake of elements under Al stress. The efficiency ratio (ER) assisted in differentiating legumes entries into efficient and inefficient utilizers of absorbed nutrients. The ER is defined as milligrams of dry shoot weight produced per milligram of element in the shoot. The presence of Al in the growth medium reduced the ER for all elements. With a few exceptions, ER for various elements, gave positive correlations with shoot weight. The species and cultivars used in this study showed inter‐ and intraspecific differences in growth, uptake of nutrients and nutrient efficiency ratios in the presence or absence of Al stress.