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Abstract
The root defect of carrot (Daucus carota L.) called cavity spot is injury due to feeding of the fungus gnat larvae, Bradysia impatiens (Joh.). In sand cultures and in the field, carrots treated with the systemic insecticide, aldicarb (2-methyl-2(methylthio) propionaldehyde 0-(methylcarbamoyl) oxime) were free of the defect. The symptoms of cavity spot on carrot roots grown in sand culture were the same as those on field-grown roots. Eliminating Ca from the nutrient solution reduced the Ca content of roots and leaves but had no effect on the incidence of cavity spot. Plants with Ca-deficiency symptoms on the foliage produced roots that, except for size, were indistinguishable from roots of plants receiving the complete nutrient solution.
Abstract
Ancymidol foliar spray at 66 and 132 mg·liter−1 a.i. significantly decreased height, node number, leaf area, fresh weight, and dry weight of four sunflower cultivars. Ancymidol resulted in darker green leaves and increased chlorophyll content per unit area, as measured spectrophotometrically, when compared with controls. However, chlorophyll a, b, and total chlorophyll were increased in only two cultivars when measured on a weight basis using high-performance liquid chromatography (HPLC). Ancymidol increased three xanthophyll levels (neoxanthin, vio-laxanthin, and lutein) in the four cultivars, but had no effect on β-carotene when measured on a weight basis by HPLC. Chemical name used: a-cyclopropyl-a-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol).
Florida is the largest fresh-market tomato (Solanum lycopersicum L.)–producing state in the United States. Although vegetable production requires frequent water supply throughout the crop production cycle to produce maximum yield and ensure high-quality produce, overirrigation can reduce crop yield and increase negative environmental consequences. This study was conducted to evaluate and compare irrigation schedules by a real-time and location-specific evapotranspiration (ET)-based SmartIrrigation Vegetable App (SI) with a historic ET-based schedule (HI). A field study was conducted on drip-irrigated, fresh-market tomato during the Fall of 2015 and Spring of 2016 on a Florida sandy soil. The two scheduling methods (SI and HI) were evaluated for irrigation water application, plant biomass accumulation, nutrient uptake and partitioning, and yield in open-field tomato production. Treatments included 100% HI (T1); 66% SI (T2); 100% SI (T3); and 150% SI (T4). Treatments were arranged in a randomized complete block design with four replicates per treatment during the two production seasons. In both seasons, depth of irrigation water applied increased in the order of T2 < T3 < T1 < T4. Total water savings was greater for T3 schedule compared with T1 schedule at 22% and 16% for fall and spring seasons, respectively. No differences were observed among treatments for tomato biomass accumulation at all sampling periods during both seasons. However, T3 resulted in significantly greater total marketable yield compared with other treatments in both seasons. The impact of irrigation application rate was greater in fruit and leaf nitrogen accumulation compared with that of stem and root biomass. Based on the plant performance and water savings, this study concludes that under a sandy soil condition, a real-time location-specific irrigation scheduler improves irrigation scheduling accuracy in relation to actual crop water requirement in open-field tomato production.
Citrus (Citrus sp.) root length density (RLD) can help in understanding and predicting nutrient and water uptake dynamics. A study was conducted at two sites in Florida to investigate root and water distribution patterns among different irrigation and fertigation systems. The results over the 2 years showed that RLD was highest in the 0- to 15-cm soil depth and decreased with depth for all treatments at both sites. About 64% to 82% of the fibrous roots (<1 mm diameter) were concentrated in the irrigated zones of drip- and microsprinkler-irrigated trees and 18% to 36% were found in the nonirrigated zones at the Spodosol site (SS). At the Entisol site (ES), the RLD (<0.5 mm diameter) in the 0- to 15-cm depth soil for intensive microsprinkler or drip irrigation was 3- to 4-fold (nonirrigated zone) and 4- to 7-fold (irrigated zone) greater at the 0- to 15-cm soil depth than that for conventional irrigation system. The trees at SS were symptomatic for Huanglongbing (HLB; Candidatus Liberibacter asiaticus) in the second year, while those at ES were asymptomatic throughout the study. This might have limited the density and extent of root distribution at SS. The water contents remained either close to or slightly above the field capacity. The results showed higher RLD for intensive irrigation and fertigation practices in irrigated zones compared with conventional grower applications suggesting greater water and nutrient uptake potential for the former.
Initiated by DC Sanders, the Southeastern Vegetable Crops Guidelines (SVCG) represents a major regional collaborative effort of Extension Specialists from Alabama, Louisiana, Georgia, Mississippi, North Carolina, and South Carolina whose aim is to produce an annually updated, all-in-one, fits on the dashboard of your truck reference for commercial vegetable growers and Extension workers for the Southeastern US. The first edition was developed in 1998 and published in 1999 as a “for pay” publication, but subsequent editions have employed a partnering with a corporate sponsor and publication company resulting in faster turnaround for printing and a no-cost publication. Each August, a team of Extension Vegetable Specialists, Extension Plant Pathologist, Extension Weed Specialists and Extension Entomologist from around the southeastern US meet for the Southeastern Extension Vegetables Workers (SEVEW) meeting. At this 2-day meeting, the participants' primary focus is to review, rewrite, refine, and update the current year's recommendations for the next edition of the SVCG. Although this publication is mainly used by the states listed, researchers and specialists from other states (FL, KY, OK, VA, TN) annually participate in this meeting. The SEVEW meeting has developed into an opportune forum for dialogues and exchanges updating each other as to the present critical issues in our respective states. Several land-grants are in the process of or are counting the SVCG/SEVEW as part of their federally-mandated multistate programming. Additionally, the SEVCG and SEVEW meeting are officially recognized as a Regional Project by CSREES. The 2005 edition can be found at http://www.aces.edu/dept/com_veg/2005_SEVCG.pdf.
Abstract
‘Bing’ sweet cherries (Prunus avium L.) harvested at commercial maturity were commercially packed and stored in 6 low-02 and 1 high-C02 controlled atmospheres (CA) at −1.1°C for 35 days and in a second study were stored in either 1.5% 02 and 0.8% C02 or 12% 02 and 10% C02 at 5.6°, 3.3°, or 1.1°C for 23 days. Fruit stored at 0.5–2.0% 02 with 0.03% C02 maintained a higher percentage of very green stems, brighter fruit color, and higher levels of titratable acids than those stored in air at −1.1°C for 35 days. High C02 atmospheres conserved fruit brightness and TA level but did not prevent stem discoloration. The only effect of lowering temperature from 5.6° to 1.1° was a slight increase in fruit firmness after storage.