Efecto del manejo en la productividad estacional y total en avena forrajera

The objective of this study was to determine the effect of defoliation management on the seasonal and total productivity of forage oats. The three cultivars of oats used underwent through cuts according to a “3 leaves” defoliation management criterion, which consisted on a defoliation frequency each time that the plot reached 3 totally elongated leaves and leaving 5 cm of sward, and through a “lenient” defoliation management criterion, which consisted on cuttings when the plot reaches 25 cm height and leaving 11 cm sward. The experimental design was a completely randomized blocks with 3 repetitions per treatment: 3 genotypes (La Estanzuela 1095a, INIA Columba y LEAv 1612), 2 defoliation management criteria (3 leaves and lenient) and 2 sowing times (early and late). In each plot the biomass production and nutritional composition was determined, as well as the height and the NDVI value before the defoliation. With an entire plant sample the structure of the plant was also evaluated and during the course of the experiment the number of tillers per square meter was counted. Choosing early sowing dates allows a greater forage production, which differences are spotted mainly in it´s bigger fall production. The 3 leaves defoliation management criterion reaches a greater forage production. Different genotypes have different seasonal and total forage production. E1095a cultivar presents greater biomass and nutrient production during the whole lifecycle, meanwhile INIA Columba achieves high productions in the vegetative phase in detriment of the spring production. LEAv 1612 obtains the lower productions in the vegetative phase but attains greater spring production potential. The settle for the defoliation management criteria to be used takes superior significance in early sowing dates, due to the differentiation between both managements, meanwhile there are no differences between both in the late sowing dates. The present work confirms that there are different responses to the employed defoliation management according to the genotype used, considering that E1095a is apparently insensitive to the management, while INIA Columba and LEAv 1612 have certain grade of response to it, generally in favour of 3 leaves defoliation management. In this work was attested that the quality increasement compensates the lower forage production of the lenient management (except for spring), as there is no difference between the defoliation management criteria in the digestible dry matter (DDM.ha^-1) harvested and even that the lenient management achieves a greater crude protein harvest during the vegetative cycle. Early sowing dates are able to achieve a greater production of nutrients than the late sowing dates. However, only when the forage oats have been sown early, it´s necessary to apply a 3 leaves defoliation management criterion in order to maximize the digestible dry matter production. Late sowing dates allow to apply any of the two defoliation criterions with no difference in nutrient production. A higher tiller population was seen under the lenient defoliation management criterion. The defoliation heights and swards were also seen to have an impact on the plant structure. In this study, the productivity estimation through the NDVI and average plant height on the plot was not sufficiently precise to be able to achieve a good prediction. When comparing the two predictions, using the average plant height seems to be more precise than the NDVI.