**8. Threat to landrace diversity**

The current industrial agriculture system may be the single most important threat to biodiversity [2]. Also, Sarker and Erskine [52] opined that a serious consequence of biodiversity loss is the displacement of locally adapted landraces with adaptation traits to future climates by monocropping with genetically uniform hybrids and improved cultivars. Modern agriculture has contributed to decreasing agricultural biodiversity as most of humankind lives now on only crops, with wheat (*Triticum aestivum*) L.), rice (*Oryza sativa* L.), maize (*Zea mays* L.) and potato (*Solanum tuberosum* L.) accounting for 60% of diets [2]. For example, 74% of rice cultivars in Indonesia are derived from the same stock, while 50% of wheat, 75% of potato and 50% of soybeans in the USA. The genetic erosion was estimated at 72.4 and 72.8%, respectively [53]. Furthermore, the number of rice cultivars declined in India farms from about 400,000 before colonialism to 30,000 in the mid-nineteenth century with unknown thousands more being lost after the Green Revolution. Greece also lost 95% of its wheat landraces after being encouraged to replace them with modern cultivars.

may arise from a number of different homozygotes and the occurrence and frequency of heterozygotes in populations. The assessment of genetic diversity between and within wheat landraces is essential to utilize landraces as donors of traits in wheat breeding and to identify

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Landraces could act as donors of important characteristics, such as drought and cold tolerance and mainly grain quality. In general, they represent significantly broader genetic diversity than modern varieties, and, therefore, they could contribute to extend the genetic base of modern cultivars. The identification of quality parameters such as protein content, gluten strength, yellow pigment and their integration in the improved varieties is a priority in research on durum wheat [57]. Mineral content in modern wheat cultivars has significantly decreased, including copper, iron, magnesium, manganese, phosphorus, selenium and zinc. High levels of these nutrients can be found in landraces and old low-yielding varieties [56]. Landraces displayed a wide range of genetic diversities. This local germplasm forms an interesting source of favorable quality traits such as protein content, gluten strength and yellow pigment content useful to durum wheat breeders. The persistent cultivation of durum wheat landraces in some regions attests to their continued value to farmers and to their competitive agronomic or nutritional advantage relative to modern varieties. Adding value of these landrace is the main motivating factor for their on-farm conservation. Fungi seed treatment against seed-borne diseases and chemical weeding at the right time could improve the land-

Furthermore, composite landraces made up of promising lines selected from landraces could be another way for durum wheat landrace valorization. But, on-farm conservation of durum wheat genetic resources in Morocco could be more efficient provided that legislation changes are made that make it possible to market landraces as diversified genetic materials and encourage their consumption [56]. Durum wheat landraces have over many generations become adapted to the local environment and cultural conditions under which they are grown. Development of new varieties from landraces could be a viable strategy to improve

yield and yield stability, especially under stress and future climate change conditions.

Rice is among the most important crops worldwide. While much of the world's rice harvest is based on modern high-yield varieties, traditional varieties of rice grown by indigenous groups have a great importance as a resource for future crop improvement. These local landraces represent an intermediate stage of domestication between a wild ancestor and modern varieties, and they serve as reservoirs of genetic variation. Such genetic variation is influenced both by natural processes such as selection and drift and by the agricultural practices of local farmers. How these processes interact to shape and change the population genetics of landrace rice is unknown [58]. Compared to new rice cultivars, rice landraces have more complex genetic backgrounds and more abundant genetic diversity and heterogeneity, as well as strong adaptability to the environment, excellent resistance to diseases and pests, high yields

priority areas for on-farm conservation.

race productivity in a simple way.

**12. Rice**
