Ecophysiological responses of johnsongrass to corn water competition.

ACCIARESI, HORACIO; ZULUAGA, MARÍA SOLEDAD; WEBER, CHRISTIAN; YANNICCARI, MARCOS EZEQUIEL

Congreso; 2012 Weed Science Society of America Annual Meeting; 2012

WSSA

In an environment under water deficit and competition, weed species may show inefficient water use. In order to determine the strategy of water consumption of Zea mays and Sorghum halepense under two soil water availability conditions, soil (Ys) and leaf water potential (Yl) , relative water content (RWC) and leaf gas exchange parameters were measured during the critical period of crop competition in pot experiments where these species where grown alone (one plant per pot) or in competition (one plant of each species per pot). In addition, , relative yield total and aggressivity index of both components were calculated. S.halepense showed continuous absorption of water, reaching a lower Yl than Z.mays hybrids. S.halepense maintained a RWC above 90%, and decreased to 70% only in competition under low water availability. In Z.mays, RWC declined to values of 70% for both water levels studied. S.halepense showed an active leaf gas exchange. Z.mays hybrids showed lower competitive ability than S.halepense for both competition levels due to a conservative strategy for water use. Sustained water use by the weed could be the cause of the increased aggressivity of S.halepense under water deficit conditions.