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.
Part of the book: Integrated View of Population Genetics
Rice (Oryza sativa) is the staple food for more than 3.5 billion people worldwide. Yield levels in Asia have tripled and are expected to increase by 70% over the next 30 years due to population growth. In the US, Arkansas accounts for more than 50% of rice production. Over the last 68 years, rice production has continued to grow in Mississippi, placing it in fourth place after Arkansas, Louisiana, and California. Due to increasing rice acreage, regionally and worldwide, the need to develop abiotic stress tolerant rice has increased. Unfortunately, current rice breeding programs lack genetic diversity, and many traits have been lost through the domestication of cultivated rice. Currently, stressors stemming from the continued effects of climate change continue to impact rice. This chapter highlights current research that strives to discover abiotic and biotic stress tolerant rice. This chapter calls for directed research in genetics and genomics to address the need to discover biotic and abiotic stress tolerant traits. While many genes have been uncovered to arm rice against these stresses, decreased genetic variability in current rice traits presents a small gene pool for discovery.
Part of the book: Plant Stress Physiology