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Transplanting kohlrabi (Brassica oleracea var. gongylodes), a cool-season vegetable crop, in early spring may provide the opportunity for double cropping in short-season regions such as the Northeastern United States. A two-year field study evaluated the impacts of transplanting dates on yield and nutrient concentration of kohlrabi. Additionally, this study aimed to quantify the nutritional value of kohlrabi leaves. The yield of kohlrabi increased by as much as 307 kg ha−1 for each day transplanting was delayed. Soil temperature increased by 2.8 °C between April 23 and May 14, resulting in the increased accumulation of Ca, Cu, Mn, and Fe in kohlrabi bulbs and Ca and Cu in leaves. The nutrient concentration in leaf and bulb were positively correlated, indicating that the two commodities can be simultaneously harvested for optimum quality. Leaf yield was not significantly different among transplanting dates. However, the number of leaves and total leaf area increased with delayed transplanting. Leaf yield and leaf area were not correlated with bulb yield, suggesting that the reductions in yield and nutrient concentrations were unrelated to photosynthetic efficiency. Although the earlier transplanting of kohlrabi may have provided opportunities for double cropping, the yield and nutrient accumulation of kohlrabi transplanted early in the spring were considerably compromised. [ABSTRACT FROM AUTHOR]

Transplanting kohlrabi (Brassica oleracea var. gongylodes), a cool-season vegetable crop, in early spring may provide the opportunity for double cropping in short-season regions such as the Northeastern United States. A two-year field study evaluated the impacts of transplanting dates on yield and nutrient concentration of kohlrabi. Additionally, this study aimed to quantify the nutritional value of kohlrabi leaves. The yield of kohlrabi increased by as much as 307 kg ha−1 for each day transplanting was delayed. Soil temperature increased by 2.8 °C between April 23 and May 14, resulting in the increased accumulation of Ca, Cu, Mn, and Fe in kohlrabi bulbs and Ca and Cu in leaves. The nutrient concentration in leaf and bulb were positively correlated, indicating that the two commodities can be simultaneously harvested for optimum quality. Leaf yield was not significantly different among transplanting dates. However, the number of leaves and total leaf area increased with delayed transplanting. Leaf yield and leaf area were not correlated with bulb yield, suggesting that the reductions in yield and nutrient concentrations were unrelated to photosynthetic efficiency. Although the earlier transplanting of kohlrabi may have provided opportunities for double cropping, the yield and nutrient accumulation of kohlrabi transplanted early in the spring were considerably compromised.

Kohlrabi is considered an important dietary vegetable worldwide. In this study, we investigated the growth and accumulation of phenolic compounds (PCs) and glucosinolates in sprouts of pale green and purple kohlrabi (Brassica oleracea var. gongylodes) in response to light and dark conditions. Pale green kohlrabi presented high fresh weight and root length irrespective of light treatment, whereas under dark conditions, it presented higher fresh weight and shoot length than purple kohlrabi. In contrast, the root length of both kohlrabies increased markedly under light conditions compared to that under dark conditions. Thirteen PCs and eight glucosinolates were detected and quantified in 10-day-old pale green and purple kohlrabies. In both kohlrabies, the individual and total phenolic levels were much higher under the light treatment than under the dark treatment. Under light and dark conditions, the total phenolic content was 6362.13 and 5475.04 µg/g dry weight in the pale green kohlrabi, respectively, whereas in the purple kohlrabi, it was 10,115.76 and 9361.74 µg/g dry weight, respectively. Dark conditions favored higher accumulation of glucosinolates than light conditions. Progoitrin, neoglucobrassicin, glucoerucin, and 4-methoxyglucobrassicin were the predominant glucosinolates in both kohlrabies and were present in much higher amounts in the pale green kohlrabi. In pale green kohlrabi under dark conditions, the total glucosinolates content was 4.75 and 2.62 times higher than that of the purple kohlrabi under light and dark conditions, respectively. Among individual glucosinolates, in the pale green kohlrabi under the dark condition, progoitrin was found to have the highest content, which was 90.28 and 54.51 times higher than that in the purple kohlrabi under light and dark conditions, respectively. These results show that the phenolic and glucosinolates levels varied widely, and these variations between the two types of kohlrabi under both light and dark conditions were significant. Our findings suggest that light and dark conditions enhance the accumulation of PCs and glucosinolates, respectively, during the development of kohlrabi seedlings.

Kohlrabi is considered an important dietary vegetable worldwide. In this study, we investigated the growth and accumulation of phenolic compounds (PCs) and glucosinolates in sprouts of pale green and purple kohlrabi (Brassica oleracea var. gongylodes) in response to light and dark conditions. Pale green kohlrabi presented high fresh weight and root length irrespective of light treatment, whereas under dark conditions, it presented higher fresh weight and shoot length than purple kohlrabi. In contrast, the root length of both kohlrabies increased markedly under light conditions compared to that under dark conditions. Thirteen PCs and eight glucosinolates were detected and quantified in 10-day-old pale green and purple kohlrabies. In both kohlrabies, the individual and total phenolic levels were much higher under the light treatment than under the dark treatment. Under light and dark conditions, the total phenolic content was 6362.13 and 5475.04 µg/g dry weight in the pale green kohlrabi, respectively, whereas in the purple kohlrabi, it was 10,115.76 and 9361.74 µg/g dry weight, respectively. Dark conditions favored higher accumulation of glucosinolates than light conditions. Progoitrin, neoglucobrassicin, glucoerucin, and 4-methoxyglucobrassicin were the predominant glucosinolates in both kohlrabies and were present in much higher amounts in the pale green kohlrabi. In pale green kohlrabi under dark conditions, the total glucosinolates content was 4.75 and 2.62 times higher than that of the purple kohlrabi under light and dark conditions, respectively. Among individual glucosinolates, in the pale green kohlrabi under the dark condition, progoitrin was found to have the highest content, which was 90.28 and 54.51 times higher than that in the purple kohlrabi under light and dark conditions, respectively. These results show that the phenolic and glucosinolates levels varied widely, and these variations between the two types of kohlrabi under both light and dark conditions were significant. Our findings suggest that light and dark conditions enhance the accumulation of PCs and glucosinolates, respectively, during the development of kohlrabi seedlings. [ABSTRACT FROM AUTHOR]