EFFECT OF CUTOFF FREQUENCIES ON PRODUCTIVITY AND CRUDE PROTEIN CONTENT IN FOUR CLONES OF PENNISETUM PURPUREUMCULTURED IN LUVISOLIC SOILS

The objective of this study was to evaluate the forage production and the crude protein content of the OM-22, CT-115, CT-169 and Purple King grass clones of Pennisetum purpureum by three cutoff frequencies. The experiment was carried out in the Chetumal Experimental Field of INIFAP in Quintana Roo, with humid subtropical climate Aw1, at 10 masl, temperature of 27.6 ° C and an average annual precipitation of 1300 mm. The soils of the study area are the so-called luvisols. An experimental design block randomly was used in an arrangement of divided plots where the largest plot was the species under study and the sub-plot the cutoff frequency (60, 90 and 120 days) with 3 repetitions per treatment. The sowing was done in plots of 4 x 9 m, samplings were carried out according to the cutting date. Statistical Analysis System (SAS) was used for ANOVA procedure, statistical analysis and means comparison accord Tuckey test. The variables measured were: plant height (PH), plant circumference average (PCA), leaf length (LL), leaf width (LW), shoots number average (SNA), buds number average (BNA) and dry matter production (DMP). Results indicated differences (P <0.05) for cutting frequencies (60.90 and 120) and clones, in the variables: PH with 176.5, 189 and 2.5 cm respectively, for LL with 91.1, 95.6 and 99.2 cm, BNA for cuts the trend was 8.1, 7.4 and 5.4 buds per ten stems for 120, 90 and 60 days respectively. Among clones the average values ​​were 9.9, 8.7, 7.5 and 6.6, for CT169, King grass purple, OM22 and CT 115, respectively. For PCA the results indicate differences among clones and cutting frequencies. For DMP, results indicated that differences were observed for cuts (P≤0.05) where the highest DMP was 120 days followed by 90 and 60 with averages of 70, 44 and 31 ton DM/ha respectively. For interaction, the highest average was 78 ton DM/ha for the clone OM22 cut to 120 days.