MORPHO-ANATOMICAL FEATURES OF WEED FLORA OF RAINFED MAIZE FIELDS IN MIR ALI, NORTH WAZIRISTAN AGENCY, PAKISTAN

Morphological and anatomical study of eight prevalent weed species belonging to seven different families present in maize fields of Mir Ali, North Waziristan Agency, Pakistan was conducted during August and September of 2009 and 2010. The study comprised of noxious weeds like, Alhagi maurorum, Amaranthus viridis, Conyza bonariensis, Digera arvensis, Lippia nodiflora, Oxalis corniculata, Polygonum barbatum and Portulaca oleracea at full vegetative growth stages. Permanent microscopic preparations were made to measure and analyze elements of the anatomy of stems and root (epidermis, cortex, collenchyma, central cylinder and diameter). It was concluded that, Alhagi maurorum equipped with elaborate vascular bundles both in root and stem clarified its adaptation in the severe rainfed climate of the area. Because of its significant seed dispersal, it is acclimatized throughout the area. Other weeds like Amaranthus viridis, Conyza bonariensis, Digera arvensis, Lippia nodiflora, Oxalis corniculata, Polygonum barbatum and Portula caoleracea having the peculiar characteristics of typical mesophyte are well adopted and can complete their life cycle along with the maize crop. Due to special morphological and anatomical features of majority of the species studied, the capacity of rapid absorption of water along with minerals from the soil are enough to compensate the rapid loss of water, and thus can be easily adopted along with the maize crop.