Search Results

Kale (Brassica oleracea L.) ranks highest among vegetable crops for lutein and beta-carotene carotenoids, which function as antioxidants in disease prevention. Nitrogen (N) rate and N form influence plant growth and alter pigment composition and accumulation. The objectives of these experiments were to investigate the effect of N rate and form on biomass and accumulation of plant pigments in the leaf tissues of kale. Three kale cultivars were grown using nutrient solution culture. In the first study, N treatment rates were 6, 13, 26, 52, and 105 mg·L^–1, at a constant NH₄-N:NO₃-N ratio. Kale biomass increased linearly in response to increasing N rate. On a fresh weight basis, lutein and beta-carotene were not affected by N rate. However, carotenoids calculated on a dry weight basis increased linearly in response to increasing N rate. In a second study, kale was grown under: 100% NH₄-N:0% NO₃-N, 75% NH₄-N:25% NO₃-N, 50% NH₄-N:50% NO₃-N, 25% NH₄-N:75% NO₃-N, and 0% NH₄-N:100% NO₃-N, at a N rate of 105 mg·L^–1. Linear increases in biomass were observed for each kale cultivar as percentage of NO₃-N increased. Lutein concentrations increased 155%, 73%, and 39% for `Toscano', `Winterbor', and `Redbor' kale, respectively, as N form changed 0% NO₃-N to 100% NO₃-N. Concentration of leaf beta-carotene increased linearly in response to increasing NO₃-N in each cultivar tested. Nitrogen management should be considered in crop production programs designed to increase the concentrations of nutritionally important carotenoids.

Therapeutic compounds in herbal crops are gaining recent attention. Sweet basil (Ocimumbasilicum L.) is a popular culinary herbal crop grown for both fresh and dry leaf markets. Recently, basil (unidentified cultivar) was shown to rank highest among spices and herbal crops for xanthophylls carotenoids. This class of carotenoids is associated with decreased risks of certain cancer and age-related eye diseases. The research goal for the current study was to characterize the concentrations of nutritionally important carotenoid pigments among popular varieties of basil. Eight cultivars of sweet basil (`Genovese', `Italian Large Leaf', `Nufar', `Red Rubin', `Osmin Purple', `Spicy Bush', `Cinnamon', and `Sweet Thai') were grown in both field and greenhouse environments and evaluated for plant pigments using HPLC methodology. Environmental and cultivar differences were significant for all of the pigments analyzed. `Sweet Thai' accumulated the highest concentrations of lutein, zeaxanthin, and beta-carotene carotenoids, while `Italian Large Leaf' had the lowest concentrations. Comparing the two environments, cultivar means for carotenoid and chlorophyll pigments were higher in the field environment when expressed on both a fresh and dry weight basis. Exceptions were found only for the purple leaf basils (`Osmin Purple' and `Red Rubin'). Positive and highly significant correlations existed between carotenoid and chlorophyll pigments in both environments. This study demonstrates that sweet basil can accumulate high levels of nutritionally important carotenoids in both field and greenhouse environments.

Sweet basil (Ocimum basilicum L.) is a popular culinary herbal crop grown for fresh or dry leaf, essential oil, and seed markets. Recently, basil was shown to rank highest among spices and herbal crops for xanthophyll carotenoids, which are associated with decreased risks of cancer and age-related eye diseases. The research goal for the current study was to characterize the concentrations of nutritionally important carotenoid pigments in popular varieties of basil. Eight cultivars of sweet basil (`Genovese', `Italian Large Leaf', `Nufar', `Red Rubin', `Osmin Purple', `Spicy Bush', `Cinnamon', and `Sweet Thai') were grown in both field and greenhouse environments and evaluated for plant pigments using HPLC methodology. Environmental and cultivar differences were observed for all of the pigments analyzed. `Sweet Thai' accumulated the highest concentrations of lutein, zeaxanthin, and β-carotene carotenoids in the field, while `Osmin Purple' accumulated the highest carotenoid concentrations in the greenhouse. Comparing the two environments, cultivar levels for carotenoid and chlorophyll pigments were higher in the field environment when expressed on both a fresh and dry weight basis. Exceptions were found only for the purple leaf basils (`Osmin Purple' and `Red Rubin'). Positive correlations existed between carotenoid and chlorophyll pigments in both environments. This study demonstrates sweet basil accumulates high levels of nutritionally important carotenoids in both field and greenhouse environments.

In the present study, carotenoid concentrations and profiles of carotenoids were determined at harvest and during storage in fruit of several cultigens of winter squash, including several New Hampshire (NH) breeding lines, the cultivars Waltham Butternut and Puritan Butternut in Cucurbita moschata (Duch.), and the hybrid cultivars Sunshine, Eclipse, Space Station, and Thunder in Cucurbita maxima (Duch.). Cultigens were grown at research farms in either Madbury or Durham, NH, in 2007, 2008, and 2009, and fruit were harvested at either 40 or 60 days after pollination (DAP), and stored for 0, 30, or 60 days at 14 °C before sampling. Total carotenoid concentrations were determined spectrophotometrically and carotenoid profiles were determined using high-performance liquid chromatography (HPLC). Carotenoid concentrations in fruit samples of C. maxima cultigens harvested at 60 DAP ranged from 146 to 320 μg·g⁻¹ fresh weight (FW), compared with concentrations of 274 to 623 μg·g⁻¹ FW after storage for 60 days. Carotenoid concentrations were lower among C. moschata cultigens, ranging from 42 to 145 μg·g⁻¹ FW at 60 DAP, and from 84 to 239 μg·g⁻¹ FW after 60-day storage. The nutritionally important carotenoids, lutein, zeaxanthin, and β-carotene, comprised 41% to 63% of the total carotenoid profile in the C. maxima kabocha hybrids; whereas, the carotenoids neoxanthin and flavoxanthin comprised 37% to 59%. β-Carotene and lutein were the major nutritionally beneficial carotenoids identified in ‘Waltham Butternut’ and three inbred lines of C. moschata, along with much smaller concentrations of α-carotene. Neoxanthin and violaxanthin comprised between 14% and 29% of the total carotenoid profiles among the four cultigens analyzed. In the popular cultivar Waltham Butternut, the β-carotene concentration was 17.3 μg·g⁻¹ FW at 60 DAP, but increased to a maximum of 57.8 μg·g⁻¹ FW after storage for 30 days; whereas, lutein concentrations increased from 27.3 μg·g⁻¹ FW at 60 DAP to 44.6 μg·g⁻¹ FW after 60-day storage. In Sunshine, a popular kabocha cultivar, β-carotene increased from 26.0 μg·g⁻¹ FW at 60 DAP to 104 μg·g⁻¹ FW after 60-day storage. Lutein + zeaxanthin concentrations in ‘Sunshine’ were 58.8 μg·g⁻¹ FW at 60 DAP, but increased only to 71.8 μg·g⁻¹ FW after 60-day storage. Total carotenoid concentrations and carotenoid profiles in ‘Sunshine’ over three growing seasons, and in ‘Waltham Butternut’, ‘NH.Mo421’, and ‘NH.Mo851’ over two growing seasons, were similar.

Crop plants are adversely affected by a variety of environmental factors, with air temperature being one of the most influential. Plants have developed a number of methods in the adaptation to air temperature variations. However, there is limited research to determine what impact air temperature has on the production of secondary plant compounds, such as carotenoid pigments. Kale (Brassica oleracea L.) and spinach (Spinacia oleracea L.) have high concentrations of lutein and β-carotene carotenoids. The objectives of this study were to determine the effects of different growing air temperatures on plant biomass production and the accumulation of elemental nutrients, lutein, β-carotene, and chlorophyll pigments in the leaves of kale and spinach. Plants were grown in nutrient solutions in growth chambers at air temperatures of 15, 20, 25, and 30 °C for `Winterbor' kale and 10, 15, 20, and 25 °C for `Melody' spinach. Maximum tissue lutein and β-carotene concentration occurred at 30 °C for kale and 10 °C for spinach. Highest carotenoid accumulations were 16.1 and 11.2 mg/100 g fresh mass for lutein and 13.0 and 10.9 mg/100 g fresh mass for β-carotene for the kale and spinach, respectively. Lutein and β-carotene concentration increased linearly with increasing air temperatures for kale, but the same pigments showed a linear decrease in concentration for increasing air temperatures for spinach. Quantifying the effects of air temperature on carotenoid accumulation in kale and spinach, expressed on a fresh mass basis, is important for growers producing these crops for fresh markets.

Green leafy vegetables are important sources of dietary carotenoids, and members of Brassica oleracea L. var. acephala rank highest for reported levels of lutein and β-carotene. Twenty-three leafy B. oleracea cultigens were field grown under similar fertility over two separate years and evaluated for leaf lutein and β-carotene accumulation. Choice of B. oleracea cultigen and year significantly affected carotenoid levels. Lutein concentrations ranged from a high of 13.43 mg per 100 g fresh weight (FW) for B. oleracea var. acephala `Toscano' to a low of 4.84 mg/100 g FW for B. oleracea var. acephala 343-93G1. β-carotene accumulations ranged from a high of 10.00 mg/100 g FW for B. oleracea var. acephala `Toscano' to a low of 3.82 mg/100 g FW for B. oleracea var. acephala 30343-93G1. Carotenoid concentrations were significantly higher in year 2 than in year 1, but rank order among the cultigens for both lutein and ß-carotene did not change between the years. During each year, there were high correlations between leaf carotenoid and chlorophyll pigments. Under similar growing conditions, choice of B. oleracea cultigen will influence carotenoid accumulation, and this may affect the health benefits of consuming these leafy green vegetable crops.