Comparison of the agronomic and commercial characteristics of traditional carob cultivars and selected high kernel yield clones in Spain

The carob tree (Ceratonia siliqua L.) shows interesting commercial potential for some coastal Mediterranean growing areas. Carob bean gum is extracted from the pod seed and is a valuable stabilizer and thickener for the food industry. The selection of carob cultivars that produce high seed yields in Spain would be of interest to growers. Since the 1990s several carob female and hermaphrodite clones have been introduced in the carob experimental plots in Tarragona province (Catalonia) to improve the pollination and regular yields of the new intensive orchards. Vegetative, fruiting and pod characteristics were field evaluated for three traditional carob cultivars (‘Matalafera’, ‘Rojal’ and ‘Duraió’) and nine accessions for their high kernel yield, six female and three hermaphrodite ecotypes. The observations were carried out in the 4-year period, 2014-2017. The vegetative development of the hermaphrodite accessions ‘E-13P’, ‘A-19’ and ‘Turis’ were lower than all the female cultivars. Regarding early bearing of cultivars, important differences were found, being those mentioned above the most precocious ecotypes (3^rd year after budding). So far in relation to productivity during the 12 years after budding, accessions like ‘A-19’, ‘E-13P’, ‘SdC’, and ‘Rojal’ appeared to be more yielding. Another interesting trait observed was the difference in fruit ripening and natural fruit drop, ‘Matalafera’ and ‘E-4’ showed earlier ripening and easy fruit drop. Fruit records of samples from young producing trees were taken. ‘Duraio’, ‘E-26’ and ‘E-19’ produced the largest pods (over 20 g of fruit weight) with 15, 18 and 20% kernel content, respectively. However, ‘E-18’, ‘E-4’, ‘SdC’ and ‘E-13P’ produced the smallest fruits (weighing 14 to 17 g) with also the highest kernel content (17-19%). Gum content, expressed as a percentage of the dry weight, was higher in ‘E-18’ (62.7%) and lowest in ‘A-19’ (51.8%). So far the resulting information indicates that ‘Duraio’ cultivar, three accessions (‘SdC’, ‘E-4’, and ‘E-19’) and two hermaphrodite pollinators (‘Turis’ and ‘E-13P’) seem suitable to be used as new cultivars for pod and kernel production in modern carob groves.