Growth rate pattern of buffelgrass {[}Pennisetum ciliare L. (Link.) Syn. Cenchrus ciliaris L.] in Tamaulipas, Mexico

Abstract

The purpose of this research was to learn on the crop growth rate (CGR), leaf area index (LAI), leaf:stem (LS) ratio, and the dead tissue:live tissue (DL) ratio of buffelgrass {[}Pennisetum ciliare L. (Link.) Syn. Cenchrus ciliaris L.], as functions of rainfall (precipitation, i.e.: PREC), soil moisture at 20 (SM20) and 40 (SM40) cm, growing degree days (GDD), solar radiation, heliothermal units, and evapotranspiration. From July 1999 to December 2000, five time-overlapped cut programs were designed in order to perform weekly pasture harvests, under a 3-replicate, randomized block design. Multivariate analysis as principal components and conglomerate analyses together with regression analysis were performed. Eighty five (85) percent variability could be explained by three principal components. Three treatment groups were formed (P<0.01). Group 1: spring/late-fall harvests showing moderate CGR (16.36 +/- 14.38 kg ha(-1) d(-1)) limited by SM20 and GDD. Group 2: summer harvests with 28.56 +/- 23.3 kg ha(-1) d(-1) (CGR), 1.49 +/- 0.7 (LS) and 0.64 +/- 0.4 (LAI) restricted by PREC. Group 3: winter harvests with 5.1 +/- 7.8 kg ha(-1) d(-1) (CGR), limited by GDD and SM20. SM20 explained 87 \%, and PREC explained 92 \% of CGR variation for Groups I and 2, respectively. Spring growth rates could not be predicted since no rainfall events were recorded in that time, during the studied period. Under the conditions of this study, it is possible to predict buffelgrass growth rates during summer and fall.