A qualidade de sementes de buva pode ser reduzida devido à resistência a glyphosate?

Abstract

The resistance to glyphosate may provide a penalty on plant growth and physiology. We investigate if the resistance to glyphosate reduces the seed quality of Conyza bonariensis by performing seed viability and vigor tests under a completely randomized design with four replicates of 50 seeds for both glyphosatesusceptible (S) and -resistant (R) biotypes. Low seed viability (<50%) was found in both S and R biotypes. No difference occurred between either S and R biotypes on seed germination and embryo viability. The percentage of seed germination of the S biotype was higher than the R biotype in the cold test (~58%), accelerated aging test (~84%), and high-temperature stress test (~45%). This is the first time one found evidences that resistance to glyphosate may be responsible for a penalty on seed quality of C. bonariensis.A resistência a glyphosate pode proporcionar penalidade ao crescimento e à fisiologia das plantas. Foi investigado se a resistência a glyphosate reduz a qualidade da semente de Conyza bonariensis por meio de testes de viabilidade e vigor de semente, utilizando-se de delineamento inteiramente casualizado com quatro repetições de 50 sementes tanto para biótipos suscetíveis (S) quanto resistentes (R) a glyphosate. Observou-se baixa viabilidade de sementes (<50%) nos biótipos S e R. Não houve diferença entre os biótipos S e R na germinação de sementes e na viabilidade do embrião. A porcentagem de germinação de sementes do biótipo S foi maior que o biótipo R no teste de frio (~58%), no teste de envelhecimento acelerado (~84%) e no teste de estresse por alta temperatura (~45%). Esta é a primeira vez que se observa que a resistência a glyphosate pode ser responsável por penalidade na qualidade da semente de C. bonariensis. PALAVRAS-CHAVE:Conyza bonariensis, resistência a herbicida, vigor de semente.

Stressful Conditions Affect Seed Quality in Glyphosate Resistant Conyza bonariensis (L.)

“…These results suggest that seeds of R biotypes deteriorate and die faster than seeds of S biotypes at high temperatures. These results are consistent with those observed by Costa et al [23] in C. bonariensis. At the vegetative level, there is no evidence for fitness cost in glyphosate-resistant Conyza species [5,26,28,37]; however, our results suggest that there may be a seed level fitness penalty in C. bonariensis.…”

“…The viability of seeds was low (±50% or less) in relation to other studies that have reported viability rates between 65% and 80% in R and S Conyza populations [11,19]. However, there are also cases with lower germination rates [2,23]. This discrepancy in the viability and germination rates may be due to seed longevity; in the particular case of the Conyza species, longevity is short due to the small size of seeds resulting in few stored reserves [32]; therefore, it is normal to observe the deterioration or death of seeds [15].…”

“…Tests with C. bonariensis seeds were performed according to the methods used by Costa et al [23]. The seeds used in these experiments were taken at random to avoid biases regarding the seed quality found in the field.…”