Floyd M. Woods

Plastic Mulches and Row Covers on Growth and Production of Summer Squash

ABSTRACT Row covers and colored plastic mulch are used routinely throughout the United States to grow vegetables but are rarely used in conjunction to produce a crop. Summer squash (Cucurbita pepo L.), cv. Prelude II, was grown on an Orangeburg sandy loam soil in Shorter, AL. The summer squash was direct seeded in single rows. The experiment consisted of 12 treatments including: (1) black plastic mulch (BPM)+spunbonded row cover (RC), (2) BPM alone, (3) white plastic mulch (WPM)+RC, (4) WPM alone, (5) red plastic mulch (RPM)+RC, (6) RPM alone, (7) bare soil (BS)+RC, (8) BS alone, (9) silver plastic mulch (SPM)+RC, (10) SPM alone, (11) blue plastic mulch (BLUPM)+RC, and (12) BLUPM alone. Year and mulch color affected all variables, row cover affected plant height and stem diameter, and the mulch color × row cover interaction affected yield variables. Mulch color and year significantly affected air and soil temperatures and row cover significantly affected air temperature. Soil temperatures were more than 5°C lower than air temperatures in all treatments and air temperatures were 2–5°C higher with row covers than without. Increased soil and air temperatures did not always result in yield increases. Colored plastic mulch with or without row covers did not increase early fruit yield in squash. Lack of a mulch/row cover induced temperature effect on yield was attributed to the relatively high mean air temperatures that may have masked treatment temperature effects.

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.

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.

Effect of Maturity at Harvest in Relation to Changes in Antioxidant Properties and Ethylene in ‘Chandler’ Strawberry Fruit

Abstract The relationship between fruit maturation and accumulation of hydrogen peroxide (H202), lipid peroxidation, ethylene (C2H4) production, antioxidant activity (hydrophilic, lipophilic and total) and the antioxidant enzyme ascorbate peroxidase (APX, EC 1.11.1.11) in fruit pericarp tissue of ‘Chandler’ (Fragaria xananassa Duch.) strawberry were measured. ‘Chandler’ fruit pericarp maturation and ripening were accompanied by a decline in H202 content early in fruit development followed by a rapid accumulation. An increase in membrane lipid peroxidation (thiobarbituric acid reactive substances, TBARS) coincided with accumulation of H202, which preceded a rise in C2H4 production. In general, antioxidant activity declined as fruit matured and ripened. APX enzyme activity increased by 2-fold and peaked at the pink stage of development and then gradually declined with ripening. H202 may serve as a signal molecule to initiate the cascade of oxidative processes during maturation and ripening. APX enzyme activity during maturation and ripening was not substantial and thus, may not have a role in alleviating accumulation of H202 and subsequent events related to oxidative senescence in fruit pericarp. To our knowledge, this is the first study to present fractionated antioxidant activities (HAA, LAA and TAA) from strawberry pericarp as assessed by the ABTS*+ radical cation assay. A fundamental understanding of the mechanisms involved in the senescent related-oxidative changes during strawberry fruit ontogeny in relation to quality and nutrition is discussed.

Effect of Temperature, Photoperiod and Pretreatment Growing Condition on Floral Induction in Springbearing Strawberry

Abstract ‘Chandler’ strawberry plants (Fragaria X ananassa Duch.) were greenhouse grown under natural lighting and then placed into growth chambers at two constant temperatures of 16 °C and 26 °C and two day lengths of 9 h (SD) and 9 h photoperiod (NI) which was night interrupted with 3 h of incandescent radiation at 30-45 μmol s ∼ 1m ∼ 2 PAR. Plants were given different numbers of inductive cycles in growth chambers and then moved to the greenhouse where flowering and growth were monitored. Flowering was completely inhibited at 26 °C, regardless of pretreatment growing conditions such as pot sizes and plant ages, photoperiod and inductive cycles. At 16 °C, SD promoted floral induction compared to NI under all inductive cycles except a 7-day induction. The minimum number of inductive cycles required at 16 °C for floral induction was dependent on photoperiod and prior greenhouse treatment. Flowering rate was also affected by greenhouse treatment, photoperiod and inductive cycles. Runner production was affected by photoperiod and temperature Xinductive cycle.

Effect of Primocane Topping Height and Lateral Length on Yield of ‘Navaho’ Blackberry

Abstract ‘Navaho’ erect thornless blackberry plants were subjected to a combination of three primocane summer topping heights and two lateral length pruning treatments. Plants were topped at 91, 122, 152 cm tall, and laterals were shortened to either 30 or 61 cm in length. Treatment effects on yield and plant structure were examined for four growing seasons. Lateral length had little effect on yield and any pruning height. Yield generally increased with increasing plant height. The 122-cm height appeared to optimize yield while still allowing for manageable floricane architecture.

Orchard Design Influences Fruit Quality, Canopy Temperature, and Yield of Satsuma Mandarin (Citrus unshiu ‘Owari’)

Satsuma growers in Alabama have used various orchard designs to minimize freeze damage. These designs include interplanting between pecan and pine trees, and planting behind windbreaks. Interplanting satsuma trees with pine trees resulted in warmer temperatures within the orchard, while the other orchard designs did not moderate orchard temperature during severe freeze events. Satsuma fruit harvested from plots shaded by pine tree canopies had higher soluble solids content and reduced fruit weight. Dense pine tree canopies can provide an insulating effect that reduces freeze damage and yield losses when severe freezes occur, but heavy shading can result in lower yields when damaging freezes do not occur.

Use of Floating Row Covers in Annual Hill Plasticulture Strawberries

Abstract The response of strawberry plants in the annual hill plasti-culture system to the use of lightweight nonwoven rowcovers (17g/square meter) during the fall establishment period, winter and early spring was investigated. These fabrics can provide some cold and wind dessication protection and can also increase soil and air temperatures around the plant. The increased temperatures under the cover may simulate increased flower bud formation during the short day induction cycles in the fall and spring. Additionally, the covers may provide a protective environment where leaves remain functional for longer periods and crown and root development may be stimulated. In this study, row covers were installed and removed at various intervals from October through March. In addition to the uncovered control plants, the following row cover timings were imposed: Oct.-Mar., Oct.-Feb., Oct.- Dec., Oct.-Nov., Nov.-Mar., Oct.-Feb., Oct.-Jan., Oct.-Dec., Oct.-Nov., Nov.-Mar., Dec.-Mar., Jan.-Mar., and Feb.-Mar. Treatments were reduced from 8 to 6 in the last year of the study. The weight of marketable berries was affected by year and by treatment. Average performance for the four year period showed the Oct.-Feb. treatment to have the highest yields followed by Oct.-Nov. and Feb.-Mar. The Jan.-Mar. performed worse than the control in terms of both yield and berry size. Average berry weight was improved in the Oct.-Feb. and Oct.-Nov. treatment. Row covers in the best treatment (Oct.-Feb.) improved marketable yield by an average of 35% over the control.