What lies behind a fruit crop variety name? A case study of the barni date palm from al-'Ula oasis, Saudi Arabia

Societal Impact Statement The oasis of al-'Ula is subject to a vast development operation by the central government of the Saudi monarchy. Agriculture is not strictly speaking the first objective of this initiative, the emphasis being on tourism and thus on the vast historical heritage and landscape qualities of the region. Nevertheless, agriculture and, in particular, phoeniculture remain the main resource for the inhabitants. Characterizing the local date palm agrobiodiversity is key to the sustainable development of oases. In al-'Ula, documenting indigenous knowledge about the locally predominant barni variety and characterizing its genetic integrity and mode of propagation represents the essential leverage needed by farm development project planners to develop local production. Understanding how farmers name and categorize their crops in relation to the way they are propagated is critical for a proper assessment of agrobiodiversity. Yet, indigenous knowledge is often overlooked in genetic studies, which may result in an underestimation of crop diversity, thereby preventing its conservation and mobilization for developing sustainable agroecosystems. Here, we focus on the barni date palm variety, a local elite variety of al-'Ula oasis, Saudi Arabia. We conducted an ethnobotanical survey on local phoeniculture practices and generated whole-genome data to determine whether or not barni palms are exclusively clonally (vegetatively) propagated. Further, we contrasted the genomes of barni and two other palms from al-'Ula with 112 Phoenix spp. to provide an initial insight into date palm diversity in this oasis. The survey reveals that the dates of the barni palm bear distinct names, depending on their quality. Results show that barni is a true-to-type cultivar, indicating clonal propagation by offshoots with name maintenance, even between distinct cultivating situations in al-'Ula and a nearby oasis. Nonetheless, it is distinct from the prominent barni cultivated in Oman. Its ancestry is comparable to other West Asian date palms, but another palm from this oasis shows influence from North Africa. What lies behind the cultivar name barni in al-'Ula and further afield in the Arabian Peninsula has been deciphered through the key disciplinary combination of social anthropology and genetics. Future studies will provide additional insights into the original genetic make-up of this millennia-old oasis.

Automated summary

This article discusses the impact of development in the al-'Ula oasis on local agriculture and date palm cultivation in Saudi Arabia. The research shows that the barni date palm is propagated clonally and shares genetic characteristics with other West Asian date palms. Understanding local agrobiodiversity and promoting sustainable development is crucial.