Weedy Rice: Competitive Ability, Evolution, and Diversity

Abstract

Weedy rice is conspecific, the most troublesome weed of cultivated rice identified as a threat to global rice production. The weed has inherited high reproductive ability and high dormancy by outcrossing with modern rice cultivars and wild cultivars, respectively. Traits such as rapid growth, high tillering, enhanced ability to uptake fertilizers, asynchronous maturation, seed shattering, and long dormancy periods make weedy rice more competitive than cultivated rice. Weedy rice infesting rice fields are morphologically diverse with different hull color, awn length, plant height, and variable tiller number. Morphological diversity in weedy rice can be attributed to its high genetic diversity. Introgression of alleles from cultivated rice into weedy has resulted in high genetic and morphological diversity in weedy rice. Although variations among weedy rice populations make them difficult to control, on the brighter side, competitive nature of weedy rice could be considered as raw genetic materials for rice breeding program to develop vigorous rice plants able to tolerate high biotic and abiotic stresses.

How Can Weedy Rice Stand against Abiotic Stresses? A Review

“…The ability of weedy rice to spread and persist in fields has been attributed to shattering, as the seeds that are shed before harvest will probably be a part of the input of the seedbank; shattered seeds can remain dormant in the soil for many years avoiding unfavorable abiotic stresses, contributing to increase the species fitness in the environment (Figure 3) [30,87,88]. Moreover, shattering has been considered an adaptive trait, as seeds that persist on the plant can easily be predated by animals, and if seeds are non-dormant, they could germinate under unfavorable conditions [85].…”

Evolution of imidazolinone-resistant weedy rice in Malaysia: the current status

“…The genus Oryza comprises various species and subspecies, including wild rice ( Oryza rufipogon Griff. ), cultivated rice, and weedy rice (Shrestha et al 2019). In contrast to wild rice, weedy rice is believed to have evolved from (1) outcrossing between the wild type and rice cultivars with subsequent genetic exchange between the outcrosses and wild type or the rice cultivars or among various outcrosses (Kanapeckas et al 2016; Londo and Schaal 2007; Qiu et al 2014); (2) de-domestication events of cultivars (Kanapeckas et al 2016; Li et al 2017; Olsen et al 2007; Sun et al 2019); and (3) direct establishment from wild rice populations (Huang et al 2017; Shrestha et al 2019).…”