Kernel quality evaluation of promising new almond germplasm grown in mountain and oasis agro-systems in Morocco

The main physicochemical traits of almond kernel were determined in 26 selected local almond [ Prunus dulcis (Mill.) D.A. Webb, syn . P. amygdalus (L.) Batsch] seedlings grown in four localities under two different agro-ecological systems, Mountains (Al-Hoceima and Azilal) and oasis ecosystem (Agdez and Skoura). Nut and kernel weight varied widely among genotypes, year and population. Most genotypes exhibited small to intermediate kernel weight, ranging from 0.9 to 1.4 g. All these genotypes are hard shelled with shelling percentages lower than 25%. Kernels produced at Agdez and Skoura (oasis ecosystems) are slightly heavier than those of other localities (mountains regions). Natural variability was observed among genotypes for oil content, ranging from 50 to 61% on a dry weight (DW) basis. For protein content, the value varied between 18.24 and 29.16% DW. The year effect was significant on oil and protein content. In agreement with the oil content, the protein content of the kernels produced in oasis ecosystem [Agdez (24.84% DW) and Skoura (24.58 DW)] was higher than those collected in mountain regions [Azilal (22.35% DW) and Al-Hoceima (22.54% DW)]. The analysis of fatty acids demonstrated a significant variability among genotypes for palmitoleic (5.49–7.53%), palmitic (0.35–0.64%), stearic (1.42–2.80%), oleic (61.55–76.68%) and linoleic (13.58–27.7%) acid percentages with a significant year effect. Over the two studied years, the oleic acid was higher and the linoleic acid was lower in kernels of almond grown under oasis ecosystem than in those from mountains regions. The high quality of almond kernel produced in oasis ecosystem could be due to the favourable oasis micro-climate and to the periodic supply of water and nitrogen to the underlying crops that are inter-planted with almond; however in the mountains regions, the almond is grown under drought conditions without any supplemental irrigation or technical support.