Genetic Variability of <i>Brachiaria ruziziensis</i> Clones to <i>Collaria oleosa</i> (Hemiptera: Miridae) Based on Leaf Injuries

Abstract

Collaria oleosa causes leaf injuries to the main forage grasses used for cattle feeding in Brazil. The aim of this work was to determine resistance of B. ruziziensis clones against C. oleosa. Eighty B. ruziziensis clones were maintained in greenhouse, in which C. oleosa natural infestations have been occurring in previous years. After 40 days, damage score and chlorophyll content reduction were assessed for all clones. By using these parameters, genetic gain was estimated based on REML/BLUP mixed models. We observed significant differences for damage scores and chlorophyll content reduction among B. ruziziensis clones, evidencing genetic variability in this forage specie in regard to resistance against C. oleosa. Gain derived from selection of the 10 best clones was 18.2% and 5.80% when considering the damage score and chlorophyll content reduction, respectively. The clones CNPGL BR 10, CNPGL BR 64, CNPGL BR 97 and CNPGL BR 40 presented the highest genetic gain for both damage score and chlorophyll content reduction, and then they will be selected to continue the B. ruziziensis breeding program with the possibility of maximizing genetic gain for the next generations.

Predictive approach to optimize the number of visual graders for indirect selection of high-yielding Urochloa ruziziensis genotypes

“…Some agronomic traits in U. ruziziensis and other forages are often visually assessed under field conditions because this assessment is practical and effective. Traits routinely evaluated using such techniques include i) pest and disease resistance (Silva et al 2013), ii) regrowth capacity (Berchembrock et al 2020, iii) stay-green (Wilkinson and Hill 2003), and iv) plant growth and biomass production (Burton 1982, Price andCasler 2014).…”