Efecto de tres frecuencias de riego sobre la calidad de la fibra en cuatro cultivares de algodón (Gossypium hirsutum L.) tipo upland

Abstract

In order to determine the effect of different irrigation frequencies (IF) on fiber quality of four cotton cultivars (CC) an experiment was carried out at Santa Elena de las Piñas Irrigation System, Valley of the Guarapiche River, in Maturín, Venezuela. A split-plot design was used, with three replications, main plots were the three IF (6, 9 and 12 days) and subplots were four CC (Cabuyare, Deltapine 16, Deltapine 61 and Acala 90-1). Means were tested by Duncan multiple range test. The statistical level used was 5%. Irrigation was applied by means of siphons of 2′. Two harvests were carried out, the first harvest (FH) at 107 day after sowing (DAS ) and the second harvest (SH) at 123 days. There were not significant differences for IF, CC and IF * CC interaction for the following characters: fiber content (FC) in the SH (39.80 %), fiber length (FL) in the FH (1.22 inch), fiber uniformity in the FH and SH (84.97 and 85.50 %, respectively), fiber strength (FS) in the FH (25.46 g/tex). Fiber fineness (FF) in the SH (43.33 micronaire), fiber reflectance (FR) in the SH (71.26) and fiber brightness in the FH and SH (9.56 and 9.08, respectively). For the FC in the FH there were only significant differences for CC, Deltapine 61 had a bigger FC than that Acala 90-1 and Cabu yare. For the FS in the SH, the most resistant fibers were obtained with irrigations every 9 days. The FF in the FH was bigger in Deltapine 61 and Acala 90-1 in comparison with that of Deltapine 16, the FR was bigger in CC Acala 90-1 and Deltapine 61 in comparison with that of Cabuyare. There was a significant interaction FR * C for the FL in the SH: In the 6-day IF, the shorter fibers belonged to CC Deltapine 16 (1.18 inch) and in the 12-day IF, belonged to Acala 90-1 (1.08 inch), while in the 9-day IF, the four CC had similar FL. On the other hand, in Cabuyare and Deltapine 61, the IF didn't affect the FL, while in Deltapine 16, the longer fibers occurred with irrigation every 12 days, but for Acala 90-1, this treatment produced the shorter fibers. In general, the different IF didn't affect the fiber properties markedly except for FL and FS, being these two characters, the most important ones to determine the fiber quality, for this reason, cotton irrigation must be a very important agronomic practice in order to achieve a good cotton fiber quality.