CLIMATIC GROWTH INDEX FOR THE GRASSES Brachiaria brizantha cv. MARANDU, Cynodon dactylon cv. TIFTON 85 AND Panicum maximum CV. TANZÂNIA AND ITS RELATION TO DRY MASS PRODUCTION

Abstract

ic Growth Index for the grasses Brachiaria brizantha cv. Marandu, Cynodon dactylon cv. Tifton 85 e Panicum maximum cv. Tanzânia and correlate it with their dry mass production. The experiment was made from November, 2005 to January, 2006 at the Universidade Estadual do Sudoeste da Bahia( UESB) in Itapetinga, BA, (15º 09’ 07" South, 40º 15’ 32" West). The grasses were cultivated in stonemasons with dimensions of 9X3 meters and they were irrigated by aspersion. The court height was 20 cm for the glasses Marandu and. Tanzânia and 10 cm for the Tifton 85. The were 11 courts. The experimental design was totally random experimental with two treatments (irrigated and not irrigated) and five repetitions (stonemasons). The court interval was 25 days. The multivariate statistical analysis detected that both group (treatment) and moment

(court date) had affected the dry mass production but, it was detected effect of the interaction group X moment. It was possible, with the use of the Climatic Growing Index, to estimate the glasses dry matter production in both treatments. Although, it was need specific equations for each glass and treatment which indicated the necessity of index calibration. It was possible, after this calibration, to estimate the dry mass production even under the irrigated condition. It was concluded that this index can be used in the estimation of dry mass production even under irrigated conditions. Therefore, the obtained results can be included in simulations and production modeling, for the grasses studied, when the limiting factor is climatic.

KEY WORDS: Forage production, modelling, vegetal bioclimatology