Recent changes in varietal diversity of rice in Guinea

Abstract

Rice varietal diversity was assessed in Guinea on the basis of surveys of 1679 farms located in 79 villages of the four natural regions of the country. The descriptors used were the number of known varieties, the number of cultivated varieties and Shannon's diversity and evenness index.On the basis of their use rates, varieties were classified as major or minor types at the village scale and as regionally and/or nationally eminent varieties at these scales. Varietal diversity was high, especially in forest Guinea and lower Guinea. Diversity pattern was typical of the subsistence farming system. The high share of local variety reflected the predominance of low management and low input cropping systems. The presence of improved varieties confirms farmers' openness to innovation and to the government policy of promoting improved varieties. Regional diversity reflected the agro-ecological diversity and specificities of each region, the history and the extent of rice-growing systems, and the importance of rice in the local diet. Recent dissemination of NERICA varieties has not caused any reduction of pre-existing varieties. The short-duration NERICA are mainly used as a complement to the long-duration traditional varieties and thus enhance varietal diversity. Risks of diversity erosion seem limited in the current setting of farming system and diversity structure. However, at the village level, the diversity pattern is fragile as the proportion of farmers who used each variety of the village is low and heterogeneous. A continuous monitoring of the dynamics of rice varietal diversity in Guinea is needed.

On-Farm Management of Rice Diversity, Varietal Preference Criteria, and Farmers’ Perceptions of the African (Oryza glaberrima Steud.) Versus Asian Rice (Oryza sativa L.) in the Republic of Benin (West Africa): Implications for Breeding and Conservation

“…The average number of varieties cultivated per village in the study area is low compared to that found in the villages of the island of Madagascar (10.9; Radanielina et al 2013), Guinea (24.6;Barry et al 2008), and in the Kumaun region of Indian Central Himalaya (11; Agnihotri and Palni 2007). However, the diversity maintained at the household level (2.2) is almost similar to that held by Malagasy (Radanielina et al 2013), and Indian farmers (Laishram et al 2020), but lower than those held by Nepalese farmers (Bajracharya et al 2010).…”

“…Our results regrouped the rice accessions in 21 morphological groups based on seed characteristics. This diversity is very low compared to those found in Guinea (387 rice varieties; Barry et al 2008), in Bangladesh (670 unique rice varieties; Tiongco and Hossain 2015), and in Madagascar (346 rice varieties; Radanielina et al 2013). However, as in Lao (Appa Rao et al 2002), we noted that the same rice variety could be called by different names and different varieties could have the same name.…”

“…Indeed, as rice producers in Burkina-Faso (Kam et al 2003) and as revealed by Gnacadja et al (2017), farmers in northern Benin prefer the taste of local rice varieties, considered as having a good taste. In addition, according to Barry et al (2008), the high proportion of local varieties in a region reflects the predominance of subsistence production systems with low intensification. The fact that many morphotypes are found specifically in the north can support also a low exchange of seeds between northern producers and those from other regions of the country, or even within the region itself.…”

“…The predominance of NERICA hybrid varieties among the improved rice varieties recorded in the study area could be justified by their massive introduction into Beninese agriculture due to the presence, until a few years ago of the temporary headquarters of the Africa Rice Center in Benin. According to Barry et al (2008), the government agricultural policy and the openness of farmers to innovation could also justify the presence of improved rice varieties in traditional agriculture. However, farmers abandoned NERICA varieties in the subsequent years.…”

Genome scan of landrace populations of the self-fertilizing crop species rice, collected across time, revealed climate changes’ selective footprints in the genes network regulating flowering time

“…In our case, several facts argue against the hypothesis of replacement of the old rice landraces of long DTHD ( Og-1 and Osj-1 subpopulations) by new exogenous rice varieties of shorter DTHD ( Og-2 and Osj-2 subpopulations). (i) Penetration of improved O. sativa rice varieties, with shorter duration, in the slash- and-burn based upland rice cropping system of our study area was reported to be extremely limited (Barry et al, 2009) and no breeding program exists for the improvement and release of new O. glaberrima varieties. (ii) Distance based neighbour-joining tree did not show any structuring in relation with collect time.…”