How Can Weedy Rice Stand against Abiotic Stresses? A Review

Abstract

Weedy rice is one of the most common weeds in rice cultivation in many rice areas throughout the world and it is able to cause significant yield reductions. Weedy rice is characterized by a high biological diversity that permits different populations to be identified on the basis of their morphological and physiological traits. This variability contributes to its success in different environments and allows different abiotic stresses, which are intensified by climate change, to be faced. Taller plants, enhanced tillering, seed shattering and the presence of red pericarp, variable hull coloration and awn morphology, linked to a deeper seed dormancy, are some of the traits that help weedy rice to spread in changing environments. The higher phenotypic plasticity and genetic variability of weedy rice make it more able to cope with temperature variations, intermittent water availability, soil salinity, drought conditions and increased CO2 concentrations than cultivated rice. As these abiotic stresses will become more frequent in the future, weedy rice competitiveness may be higher, with a spread of infestations. Thus, the control of weedy rice should be based on an integration of different preventive and agronomic techniques, a sensible use of herbicides and the use of suitable rice varieties.

Sensitivity to salinity at the emergence and seedling stages of barnyardgrass (Echinochloa crus-galli), weedy rice (Oryza sativa), and rice with different tolerances to ALS-inhibiting herbicides

“…This study highlighted that Baldo performed better under high salt concentrations than CL80; thus the availability of salt-tolerant rice varieties is particularly important, as the majority of the rice areas throughout the world are located near coastal areas and river deltas where salinity problems are more common (Formentin et al 2018). Moreover, some weeds can be more competitive than others in saline environments (Fogliatto et al 2020); according to our study, E. crus-galli is favored more than O. sativa under saline conditions, and thus more efforts should be made to control this weed. Populations resistant to ALS inhibitors showed variable behavior, with some populations that tolerate salt (such as the E. crus-galli r1 population) and others that can be more sensitive to salt (such as the E. crus-galli population r2 and the CL80 rice variety).…”

“…The effects of salinity on cultivated plants can be intensified by the presence of other limiting factors, such as competition due to the presence of weeds, which are in general less susceptible to environmental stresses than crops, as they are more adaptable to changes (Fogliatto et al 2020;Korres et al 2016). The higher tolerance of weeds to environmental changes is mainly related to the fact that wild species have not undergone the same level of selection to obtain advantageous traits (Korres et al 2016).…”

“…Oryza sativa populations have also developed resistance to ALS inhibitors, even though this has occurred more recently, after the introduction of Clearfield® rice varieties tolerant to imidazolinone herbicides (Goulart et al 2014;Sudianto et al 2013). Oryza sativa resistance to imidazolinone herbicides is caused by one or different point mutations in the ALS gene that result in amino acid substitution; the introduction of Clearfield® varieties harboring these mutations has increased the risk of resistant gene flow from these varieties to O. sativa; gene flow has been found to be the predominant source of resistance in O. sativa, while independent mutation is a minor source (Fogliatto et al 2020;Goulart et al 2014).…”

Sustainability, Efficiency, and Circularity of Weedy Rice Management Strategies

“…Similarly, its competitive ability is higher than crop, because it is taller and then more able to capture light, and it has a higher nutrient efficiency (especially for nitrogen use). It is also reported that weedy rice can tolerate stress conditions better than the current cultivars [21,26]. In addition, weedy rice develops several strategies in order to escape to its management.…”

Cover crops as green mulching for weed management in rice

“…weed hoeing) that can be problematic for the presence of water in the field (Chauhan, 2012). However, other techniques are already in use as an integration to chemical weed control in conventional rice production or as the only available tools in organic farming (Fogliatto et al, 2020b). Among these, the use of false seedbed technique, a good soil levelling, to obtain a uniform water depth, and rice transplanting, to favour earlier and faster rice growth compared to weeds, are the most widespread (Dass et al, 2017;Shekhawat et al, 2020).…”