Effects of Different Season on Dominant Species and Chemical Composition of Tropical Agricultural Weeds

Abstract

The study was conducted to determine the dominance level and nutritive composition of weeds during differenrt seasons. Weed sampling was done randomly on agricultural lands located in Pakem, Sleman, Yogyakarta. The method used to determine the level of dominance of weeds was by using line intercept transcect. Plant  data collected include height, width, and number of plants with different seasons as treatment. The dominant weeds were then analysed for nutritional quality using proximate analysis methods. The results showed that the level of weed species domination was higher than the legume and forb weeds in different seasons. Weeds that dominate in the dry season include Digitaria setigera, Echinochloa oryzoides, Eleusine indica, Portulaca oleracea, and Cyperus iria while in rainy season Ageratum Conyzoides, Cyperus iria, Ludwigia octovalvis, Echinochloa conola, and Echinochloa glabrescens. Based on the proximate analysis of weeds that emerged in different seasons showed that seasonal differences significantly (P<0.05) affect the nutritional content of weed grass and some forbs. Cyperus iria is one of grass weed that dry matter content during dry season (23.3%) higher than rainy season (13.9%) (P<0.05). Weeds of shrubs that contain higher dry matter during the dry season are Cleome rutidosperm (13.1%) than during rainy season (10.7%) (P<0.05%). Based on the study, it can be concluded that seasonal differences affected the nutritional content of some weed plants and t on the  dominance level of weed species.The grasses weed domination level were higher than the shrubs and the legum in the dry season and the rainy season. Seasonal differences significantly affected the content of dry weed material and some weeds and legumes.<,!!!%%! ",""-:,! !-<%"! ",,!!!-!!!, " , "" - < , , " M 7 - < , %",!,","" - : ! Digitaria  setigera Echinochloa oryzoides Eleusine  indica, Portulaca oleracea Cyperus iria , Ageratum  Conyzoides Cyperus  iria Ludwigia  octovalvis Echinochloa conola Echinochloaglabrescens-)7","" ,""!"!=^-1>""!! " , forbs- Cyperus  iria " , ! =/-/S>=/-LS>=^-1>-:" !Cleome rutidosperm=/-S> =-S> =^-1S>- ) ! !! ""!""!!",!% " , !- < , % , -""!"!""! !",,-