Monte L. Nesbitt

Cultivar Variation in Physicochemical and Antioxidant Activity of Alabama-Grown Blackberries

Abstract Blackberries are an excellent source of natural antioxidants. Fully ripened fruit of ‘Apache’, ‘Arapaho’, ‘Chester’, ‘Loch Ness’, ‘Navaho’ and ‘Triple Crown’ thornless blackberries were evaluated for their physicochemical and antioxidative activity. There were no consistent differences for variation in initial pH, titratable acidity (TA), total soluble sugar (TSS) and TSS/TA ratio values determined. Differences among cultivars with respect to reduced ascorbic acid (AA) were established, but there were no differences in either oxidized ascorbic acid (DHA) or total ascorbic acid (TAA) content. The antioxidant activity as determined by ABTS radical cation procedure for fractionated crude fruit extracts varied in response to parameters evaluated. Hydrophilic antioxidant activity (HAA) was not different among cultivars evaluated. In contrast, differences were found in lipophilic antioxidant activity (LAA) and total antioxidant activity (TAA).

Phenolic Content and Antioxidant Capacities of Alabama – Grown Thornless Blackberries

ABSTRACT Total phenolics (TPH), flavonoids (TF), monomeric anthocyanins (ACY), and Vitamin C Equivalent Antioxidant Capacities (VCEAC) utilizing ABTS and DPPH radical scavenging assays were determined for five fully ripened blackberries cultivars (‘Loch Ness’, ‘Navaho’, ‘Arapaho’, ‘Apache’, and ‘Triple Crown’) of Rubus spp. grown in Alabama. The ABTS and DPPH methods were highly correlated (R = 0.897) and the ABTS method was better for assessing the overall antioxidant capacity. Cultivar differences were found in TPH, ACY, and VCEAC as determined by the ABTS method (P ≤ 0.05) with ‘Loch Ness’ and ‘Apache’ containing the highest levels. Based on these findings ‘Apache’, ‘Arapaho’, and ‘Navaho’ are three thornless blackberry cultivars that have potential to be used as dietary supplements and for commercial production in Alabama due to high phytonutrient content, antioxidant capacities, and yield.

Comparison of Preemergence and Postemergence Weed Control Systems in Newly Established Pecan

Six weed control programs with and without irrigation were investigated in a newly established pecan orchard. Irrigation increased crown diameter growth in only one of seven growing seasons but increased nut yield an average of 35% in the first two bearing years. Weed control program significantly influenced crown diameter beginning in the fourth growing season and continued through season six while also impacting final crown diameter. The use of postemergence (POST) herbicides increased crown diameter a minimum 4 mm vs. preemergence (PRE) herbicides. Mowing neither increased nor decreased crown diameter when used with herbicides; however, when used solely, crown diameter was 29% less. Highest growth rates were obtained with a combination PRE plus POST weed management system. Nut yields were closely linked to growth data. No differences in nut yield were observed between PRE- or POST-herbicide programs alone or in combination with mowing. Mowing alone decreased nut yield 57% vs. herbicide-based approaches. A combination PRE- plus POST-weed control program increased yield 38% vs. all other treatments. Nomenclature: Pecan, Carya illinoinensis (Wang.) K. Koch var. ‘Desirable’.

Fruit Quality and Antioxidant Properties in Alabama-Grown Blackberries During Fruit Maturation

Abstract Changes in fruit quality attributes and antioxidative properties from six cultivars of thornless blackberries (Rubus sp.) (‘Apache’, ‘Arapaho’, ‘Chester’, ‘Loch Ness’, ‘Navaho’, and ‘Triple Crown’) during four different ripening stages (red, motded, shiny-black, and dull-black) were determined under Alabama growing conditions. Berry fruit samples were evaluated for pH, titratable acidity, total soluble solids, TSS/TA ratio, soluble sugars, vitamin C (reduced, oxidized, and total) and antioxidant capacity (measured as trolox equivalent antioxidant capacity, TEAC). Significant variation among cultivars and maturity of harvest were in fruit quality attributes and antioxidative properties found. An increase in fruit pH concomitant with a decline in titratable acidity (TA) was observed during ripening for all cultivars. Total soluble solids (TSS) values increased from 5.7 to 11.6%, and TSS/TA ratio ranged from 11.9 to 63.6. Highest reducing and total sugar content were contained in dull-black fruit. Vitamin C content either declined or remained unchanged with ripening and the pattern was dependent on cultivar, maturity at harvest. In general, antioxidant activity declined between red and dull-black ripening stages. The results indicate that TSS/TA ratio and TEAC were good indicators of fruit maturity and nutritional quality, respectively.