Modelling of the effects of environmental factors on rice grain discoloration incidence in Corrientes province, Argentina

Abstract

Rice grain discoloration (RGD) is a disease of complex aetiology for which there are no resistant varieties. Due to the need to better define the environmental conditions that favour the disease, the aims of this work were to (i) identify the predominant fungi associated, (ii) determine the meteorological variables most closely related, and (iii) develop preliminary weather‐based models to predict binary levels of RGD incidence. After analysing 123 rice grain samples under natural infection conditions from rice‐cropping regions throughout Corrientes province, Argentina, we found that RGD was mainly associated with Alternaria padwickii (14.2%) and Microdochium albescens (13.7%). The strongest associations between weather variables and RGD incidence were observed in a susceptible critical period (Scp) that extended from the rice flowering stage until 870 accumulated degree days (Scp lasting 32 days, ±7 days). The binary response logistic model including the weather variables DPrecT (which combined the effect of the simultaneous daily occurrence of precipitation lower than 12 mm and air temperature between 13 and 28°C), and DDMnT (sum of the exceeding amounts of daily min temperature from 23°C), was the most appropriate, showing prediction accuracy (PA) values of 84.6%. The univariate model that included DPrecT presented a PA of 82.1%. The logistic regression techniques here used to develop weather‐based models to estimate the probabilities of occurrence of binary levels of RGD can not only help to clarify and quantify the environmental effect on the development of RGD but also be useful tools to be included in future management strategies.

Phylogenomics, taxonomy and morphological characters of the Microdochiaceae (Xylariales, Sordariomycetes)

“…Hern.-Restr. & Crous was the causative agent of leaf scald and grain discoloration in rice, leading to a global decrease in rice yield ( Dirchwolf et al 2023 ). Mi.…”

Identification and fungicide sensitivity of Microdochium chrysopogonis (Ascomycota, Amphisphaeriaceae), a new species causing tar spot of Chrysopogon zizanioides in southern China

“…However, only a subset of these species can induce diseases, primarily affecting grasses and cereals. For example, M. albescens (also referred to as Monographella albescens ) typically induces leaf scald and grain discoloration in rice, leading to a global reduction in rice yield ( Araujo et al 2016 ; Dirchwolf et al 2023 ). M. bolleyi is recognised for inducing root necrosis and basal rot in creeping bent grass in Korea, as well as causing root rot on triticale in Kazakhstan ( Hong et al 2008 ; Alkan et al 2021 ).…”