Temperatura base para emissão de folhas e nós, filocrono e plastocrono das plantas daninhas papuã e corriola.

Alexander grass (Brachiaria plantaginea) and Morning glory (Ipomoea triloba) are important weeds in annual crops. The phyllochron (time interval between the appearance of two successive leaves) and the plastochron (time interval between the appearance of successive nodes) are important parameters of plant development. Thermal time is used to express time in the phyllochron and in the plastochron, and in the calculation of thermal time the value of the base temperature is needed. The objective of this study was to estimate the base temperature for leaf and node appearance, the phyllochron and the plastochron for Alexander grass and Morning glory, respectively. Data used in this paper come from an experiment with maize sown in several dates, carried out in Santa Maria, RS, Brazil, during the 2005/2006 growing season. Two plants of Alexander grass and two plants of Morning glory were left to grow in each maize plot. The main stem Haun Stage (HS) in Alexander grass and the number of visible nodes in Morning glory were measured on a weekly basis. Using the Mean Square Error (MSE) approach, base temperature was estimated as 3°C for Alexander and 7°C for Morning glory. The phyllochron in Alexander grass varied from 100.1°C day leaf-1 to 142.6°C day leaf-1 as a function of maize sowing date. The plastochron in Morning glory did not vary among maize sowing dates, with an average value of 38.8°C day node-1. [ABSTRACT FROM AUTHOR]