The objective of this work was to evaluate the interaction effect of water stress and aluminum toxicity on the initial growth and free proline contents in two cultivars of pigeon pea, IAPAR 43-Aratã and IAC Fava Larga, cultivated in hydroponics. The seedlings were submitted to stresses in nutritive solution (pH 3.8), osmotic potentials 0, -0.004, -0.006, -0.008 and -0.010 MPa, with 0, 0.25, 0.50, 0.75 and 1 mmol dm-3 Al3+ . The experiment was carried out in a plant growth room, under a luminary unit of average irradiance 190 mmol m-2 s-1 , 12-hour photoperiod and 25+1ºC temperature. A completely randomized experimental design was used in factorial arrangement 2x5x5 (two pigeon pea cultivars, five osmotic potential and five levels), with four replicates. Data were submitted to analyses of polynomial regression, cluster and main components. Water stress causes growth reduction of pigeon pea aerial part, whereas aluminum toxicity causes radicular growth reduction. There was increase of free proline contents in the two cultivars under water stress, and only in IAC Fava Larga under aluminum toxicity. Multivariate analysis showed high correlation in growth and accumulation of proline for cultivar IAC Fava Larga, evidencing probable tolerance to associated stresses.
Cajanus cajan; abiotic stress; forage crop; osmoprotector; proline
