Determination of Merremia cissoides leaf area using the linear measures of the leaflets

Knowledge of the weed leaf area may give support to study the interference relationships between weeds and crops. The objective of this research was to determine a mathematical equation for M. cissoides leaf area estimation based on the relationship between the leaf blade linear measures. Leaves of the species were collected from a variety of agroecosystems at Sao Paulo State University, Jaboticabal, Sao Paulo State, Brazil, measuring the length (L), maximum width (W) and real leaf blade area of the three kinds of leaflets. Linear equations Y = a x (X) were estimated for each kind of leaflet. The confidence intervals of the primary leaflet equation overlapped those ones from the secondary leaflet equation, and then only one equation was considered for these leaflets. So, an equation of principal leaflet plus that one of primary + secondary leaflets were used to determine the M. cissoides leaf area. Thus, the leaf area of the species might be determined by the sum of the leaf areas of the principal leaflet with the primary + secondary leaflets, according to the equation [LA.sub.est] = 0.501 x (X) + 2.181 x (Z), where X indicates L x W of the principal leaflet and Z indicates medium L x W of the primary + secondary leaflets, respectively. Keywords: weed, growth, roadside woodrose, linear fit. Determinacao da area foliar de Merremia cissoides utilizando dimensoes lineares dos foliolos. O conhecimento da area foliar de plantas daninhas pode auxiliar o estudo das relacoes de interferencia entre elas e as culturas agricolas. O objetivo desta pesquisa foi determinar uma equacao matematica que estime a area foliar de Merremia cissoides, a partir da relacao entre as dimensoes lineares dos limbos foliares. Folhas da especie foram coletadas de diferentes locais na Universidade Estadual Paulista, Jaboticabal, Estado de Sao Paulo, Brasil, medindo-se o comprimento (C), a largura maxima (L) e a area foliar de tres tipos de foliolos. Foram estimadas equacoes lineares Y = a x (X) para cada tipo de foliolo. Houve sobreposicao dos intervalos de confianca das equacoes dos foliolos primario e secundario, por isso considerou-se uma unica equacao da media desses foliolos, alem da equacao do foliolo principal, para caracterizacao da area foliar de M. cissoides. Assim, a area foliar dessa especie pode ser estimada pelo somatorio das areas dos limbos foliares dos foliolos principal e primario + secundario, por meio da equacao [AF.sub.est] = 0,501 x (X) + 2,181 x (Z), em que X indic