Flowering, fruiting and leaf and seed variability in Berberis buxifolia, a native Patagonian fruit species

Abstract

Recent findings observed on Berberis buxifolia plants grown from different spontaneous populations on Tierra del Fuego island (Argentina) are reported, as related to: (I) the floral morphology and evolution of the floral phenological phases; (II) the fruiting efficiency; (III) the pattern of fruit growth and evolution of some of the chemical attributes; and (IV) the variability found in the leaves and seeds. Flowers are solitary, axillary, bisexual, actinomorphic and hypogynous. Petals present the nectaries characteristics of the genus. Fruit is a black-blue berry (8-10 mm diameter) with an average of 3-18, moon-like shaped seeds. Bloom occurs at different times, and its beginning and duration is an accession characteristic, depending also on ecological factors. Nevertheless, seven floral phenological phases were recognized. Phenophases of blooming were measured during the spring of 2010. The length of blooming of the B. buxifolia accessions studied was 15 days between start of blooming and petal fall. Fruit number per shoot varied with the orientation and during the fruiting, being higher in the north (4.3) and west (4.0) orientations than in those from the east (2.0) and south (1.3), attaining maxima of 8.8 and 7.8 fruits per shoot respectively at day 38. Fruit efficiency then began to decrease during the ripening, attaining values of 20 to 25% for those shoots from the north and west orientations, and values of 13 to 15% for the shoots from the east and south. Fruit growth showed a typical double sigmoid curve, and it was related to compositional changes. By day 126 from full flowering phase, soluble solids (30.6 °Brix) and anthocyanin content (752.7 mg/100 g fruit fresh weight) were near their maximum values, while the total titratable acidity was at a minimum value (2.2 %). The present investigation confirmed the previous description of leaves; nevertheless a considerable variability has been observed in populations of B. buxifolia. Leaf size ranged from 0.04 to 2.08 cm2 (average 0.5 cm2); similar results were found for leaf shape (major axis/minor axis of leaf blade ranged from 1.26 to 6.25); furthermore, leaves color analysed with the RGB scale varied among populations and plants. In B. buxifolia seed number per fruit may range from 1 to 15, with an average 7 seeds/berry; results indicated that clonal selection may be applied for this trait. Seed area ranges from 5 to 16 mm2, with an average of 9 mm2; seed are lunular, mostly elongated and very elongated in shape.