Morphological variation, distribution and relationship of weedy rice (Oryza sativa L.) in Peninsular Malaysia

Abstract

The dynamic changes in agricultural practices have negatively impacted rice cultivation resulting in serious weedy rice (Oryza sativa L.) infestations. In this study, field surveys were conducted at six granaries to evaluate the abundance, spatial‐distribution patterns, and morphological characteristics of weedy rice in Peninsular Malaysia. An average of 5.28 plants/m2 weedy rice density was recorded, with coverage area that ranged from 29% to 66% and occurrence at >67% frequency. Seed morphological characteristics identified the existence of at least 18 biotypes. A total of 134 weedy rice samples were characterized morphologically, and Principle Component Analysis results showed that these samples are highly diverse and are dispersed across Peninsular Malaysia. These genetically diverse reservoir of weedy rice characteristics present opportunities of exploitation in the future, especially through rice breeding and crop improvement. Weedy rice from Kelantan and Selangor displayed unique clusters in the PCA plot which suggest higher tendencies for environmental adaptation although the influencing factors have yet to be determined. Dispersion studies based on Lloyd patchiness index revealed that more than 50% of surveyed field blocks in five states displayed uniform distribution as opposed to cluster distribution observed in the remaining field blocks. These variations in dispersion suggested that farmers in Peninsular Malaysia employed inconsistent weedy rice management practices in every granary and farm block. Observation of weedy rice infestation pattern via spatial distribution suggested that weed management requires proper coordination of control efforts among farmers to ensure the degree of infestation is maintained under a controlled level.

Comparative Metabolomics Analysis of Weedy Rice (Oryza spp.) across Peninsular Malaysia

“…This conspecific relationship allows for the direct translation of information gathered from rice metabolomics research to any studies involving weedy rice. Due to this conspecific nature, beneficial characteristics from weedy rice have significant potential to be incorporated to advance the development of rice breeding programs, especially in increasing the quality (aromatic and nutritional values) and improving the performance (a high yield, disease resistance, and abiotic stress tolerance) [24,48,49]. Our current analysis of metabolite profiles in local weedy rice from Malaysia adds further value to these efforts.…”

“…The field surveys were conducted in seven states of Peninsular Malaysia representing, the west coast region (Selangor, Perak, Penang, Kedah, and Perlis) and the east coast region (Terengganu and Kelantan) (Figure 1). These surveys were carried out during the harvesting stage between July 2017 and October 2018, in which the weedy rice samples were also collected [24]. Briefly, the collection of weedy rice samples was conducted within the survey transect at 30 m intervals, and one plant was collected at each sampling point, with a total of 30 sampling points at each location.…”

Sustainability, Efficiency, and Circularity of Weedy Rice Management Strategies

“…Third, and more important, is the evolution of IMI-resistant weedy rice populations. After 3 years of Clearfield rice cultivation, weedy rice hybrids with several trait modifications appeared in rice fields, in the USA (Louisiana and Arkansas), Brazil [38], Colombia, Costa Rica, Italy ([37]: table 3), and in Malaysia [39][40][41]. In Arkansas for instance, 10-60% of these hybrids were found to be herbicide-resistant [42].…”

Novel PCR-Based Multiplex Assays for Detecting Major Quality and Biotic Stress in Commercial and Weedy Rice

“…In addition to climate-induced stresses, the presence of weedy (or obnoxious red) rice has been reported to negatively impact rice production in several major rice-growing regions worldwide, including Malaysia [ 12 , 13 ]. Recent research, however, has revealed that weedy rice contains novel sources of stress tolerance or resistance, including to some of the most devastating rice diseases, such as blast, which can eradicate up to 30% of the crop annually [ 14 ].…”