Rice Genomics and Genetics 2024, Vol.15, No.2, 83-93 http://cropscipublisher.com/index.php/rgg 88 4.3 Ecological impacts of rice cultivation The ecological impacts of rice cultivation are multifaceted, affecting both the environment and the microbial communities associated with rice. The rhizosphere microbiome, or the microbial community in the rice root zone, is significantly influenced by rice cultivation practices. Studies indicate that the rhizosphere microbiome of cultivated rice is more sensitive to environmental changes compared to wild rice. This sensitivity is reflected in the higher diversity and more complex microbial networks observed in cultivated rice. Additionally, the domestication and subsequent cultivation of rice have led to a reduction in genetic diversity. Severe bottlenecks during the domestication process have resulted in a significant loss of nucleotide diversity in cultivated rice compared to its wild relatives. The reduction in genetic diversity may have long-term ecological impacts, potentially affecting the resilience of rice to environmental changes and diseases (Li et al., 2006). Climate and geography have shaped the pathways of domestication, while the adaptation of rice to different environments has facilitated its global cultivation. However, these processes have also led to ecological impacts, including changes in microbial communities and a reduction in genetic diversity. These impacts require further investigation to ensure sustainable rice production. 5 Agricultural Practices and Cultural Influences Traditional rice cultivation methods have been shaped by centuries of agricultural practices and cultural traditions. In many regions, rice farming relies on manual labor and simple tools, with practices varying significantly across different geographical areas. For instance, in southern China, traditional methods involve transplanting rice seedlings into flooded fields, a technique that helps control weeds and pests while ensuring ample water supply for the growing plants. In contrast, in parts of India and Southeast Asia, direct seeding is more common, where seeds are sown directly into the fields, reducing labor but requiring more careful water management (Izawa et al., 2008). Rice holds profound cultural significance in many societies, often symbolizing life, fertility, and prosperity. In China, rice is not only a staple food but also a central element in various cultural rituals and festivals, such as the Dragon Boat Festival, which commemorates the ancient poet Qu Yuan. Similarly, in Japan, rice is deeply embedded in cultural traditions, including the traditional tea ceremony and Shinto rituals, where rice is offered as a sacred food to the deities. In India, rice is an integral part of many religious ceremonies and is frequently used in offerings to gods and during weddings, symbolizing prosperity and fertility (Huang et al., 2012). The evolution of rice farming practices has been driven by technological advancements and cultural exchanges. Initially, rice domestication involved simple selection processes by ancient farmers, leading to the development of distinct rice varieties such as indica and japonica. Over time, new agricultural technologies were introduced, such as the use of irrigation systems and the development of high-yielding rice varieties, significantly boosting productivity. The Green Revolution in the mid-20th century introduced high-yielding varieties and fertilizers, transforming rice farming methods and increasing yields in many parts of Asia (Huang et al., 2012; Wang et al., 2012). Recent genomic studies have further enhanced our understanding of rice domestication and breeding. These studies have revealed the genetic basis of important traits such as disease resistance and grain quality, enabling the development of improved rice varieties through modern breeding techniques (Zhu et al., 2007). Additionally, the exchange of genetic material between ancient farmers played a crucial role in shaping the genetic diversity of rice varieties, as evidenced by gene flow between different rice subspecies (Wei et al., 2012). The domestication of rice in the Yangtze River basin is a complex process that has been extensively studied through various archaeological and environmental analyses. Archaeobotanical evidence from the Tianluoshan site in the lower Yangtze region indicates that the proportion of unbroken domesticated rice spikelet bases increased from 27% to 39% between 6 900 and 6 600 years ago. During this period, the proportion of rice remains among all plant remains also increased from 8% to 24%, suggesting a growing reliance on rice cultivation over wild food gathering (Figure 2) (Fuller and Qin, 2010; Wang et al., 2022).
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