Identificação e associação de estratégias indiretas para mensurar a resistência ao acamamento em aveia-branca

Abstract

In agriculture, the effects of plant lodging have been known for a long time, directly impacting grain yield and quality, in addition to making harvesting difficult. Research results show that lodging losses can reach up to 80%. Selection for lodging resistance in cereal breeding programs is difficult, due to the challenge of tracking related characteristics in field conditions. The identification of easily measurable characters related to lodging resistance would simplify the process of selecting new cultivars. The objective of this work was to identify and associate indirect strategies as a way of measuring resistance to lodging in modern cultivars of white oats, with different reactions regarding lodging. This study seeks to clarify why white oat cultivars of the same height class have a different expression regarding lodging. The tested hypothesis is that cultivars that have a combination of morphological, anatomical characters and structural culm carbohydrates that give culm sturdiness are more resistant to lodging. The experiment was conducted in 2018, with eight cultivars of white oats with contrasting reactions to lodging, arranged in a complete randomized block design, with three replications. Morphological, anatomical and structural carbohydrate characters were evaluated, and additionally, indices for evaluating culm resistance to lodging were tested. The data were submitted to analysis of variance, correlation and grouping. From the results obtained, it was evident that there is variability in the studied characters related to the lodging of plants in cultivars of white oats. The plant length did not show a significant association with lodging, allowing us to suppose that, for this character, due to the work of genetic improvement over the years, the plateau has already been reached. However, of the morphological characters of the stem, the length of the peduncle and the fourth internode did not show a reduction proportional to what occurred with the plant length. These characters have a greater participation in the total length of the plant, together with the internal and external diameter of the first three basal internodes that are indicated for indirect selection aiming at lodging resistance. Regarding anatomical characters, the internal vascular bundles were associated with resistance to lodging, allowing to identify it as a possible plant selection character. For structural carbohydrates in the culm, there was no significant association with resistance to lodging, allowing to assess that these characters should not be considered in the indirect selection aiming at resistance to lodging. In addition, the results made it possible to identify that the use of more objective indices to measure lodging resistance in white oat culture should be included as routine practices in breeding programs, when the objective of the selection is lodging resistance. The coefficient of culm resistance to lodging must be adopted in the selection process, as well as the culm tension test. The culm index was not associated with the other methods used, therefore, for white oat culture this index should be reviewed and suggested changes.