Diversity Among Rice Landraces Under Static (Ex Situ) and Dynamic (On-Farm) Management: A Case from North-Western Indian Himalayas

Abstract

Crop genetic diversity is the building block of sustainable agricultural development. Crop landraces contain enormous genetic diversity. The genetic structure of rice landraces is an evolutionary approach to existence and performance, especially under rainfed and to some extent under irrigated conditions in valleys and organic inputs in Himalayan agroecosystems. The combined effects of farmer and natural selection led to the building of genotypes representing diverse combinations of traits. The better understanding into the dynamics of genetic resources of rice is needed in order to identify detrimental evolutionary patterns and draw up conservation priorities. During the last two to three decades, the introduction of high-yielding varieties as well as important changes in rice farming systems has led to the loss of genetic diversity particularly from valleys in lower elevation ranges. In order to develop a rational conservation plan, in global climate change scenario, a conservation concept is required that goes far beyond ex situ conservation. In situ conservation on farm has been reflected as a backup and complementary strategy to ex situ conservation. In this scenario, the current study demonstrated farmer management and temporal evolution of rice genetic diversity in traditional production systems. The study also compared gene bank-conserved (ex situ) populations and on-farm-managed (in situ) landrace populations of same landraces Jaulia and Thapachini and revealed a greater number of alleles per locus under on-farm-managed populations as compared to static management. The marker diversity by using STMS indicates the genetic diversity among populations resulting from combined effects of many evolutionary forces operating within the biological and historical context of the landrace. The results indicated the low diversity of the populations under static management. On the other hand, the variations in adaptations indicate the degree to which populations are adapted to their environments and their potential for continued performance or as donors of characters in plant breeding. It also provides particular information on loss of diversity over time and space at allelic and genotype level. This piece of writing is a step towards understanding the impact of traditional farmer management on rice landrace populations in Himalayan agroecosystems of India.