Application of Exogenous Silicon for Alleviating Photosynthetic Inhibition in Tomato Seedlings under Low−Calcium Stress

To address the low Ca−induced growth inhibition of tomato plants, the mitigation effect of exogenous Si on tomato seedlings under low−Ca stress was investigated using different application methods. We specifically analyzed the effects of root application or foliar spraying of 1 mM Si on growth conditions, leaf photosynthetic properties, stomatal status, chlorophyll content, chlorophyll fluorescence, ATP activity and content, Calvin cycle−related enzymatic activity, and gene expression in tomato seedlings under low vs. adequate calcium conditions. We found that the low−Ca environment significantly affected (reduced) these parameters, resulting in growth limitation. Surprisingly, the application of 1 mM Si significantly increased plant height, stem diameter, and biomass accumulation, protected photosynthetic pigments, improved gas exchange, promoted ATP production, enhanced the activity of Calvin cycle key enzymes and expression of related genes, and ensured efficient photosynthesis to occur in plants under low−Ca conditions. Interestingly, when the same amount of Si was applied, the beneficial effects of Si were more pronounced under low−Ca conditions that under adequate Ca. We speculate that Si might promote the absorption and transport of calcium in plants. The effects of Si also differed depending on the application method; foliar spraying was better in alleviating photosynthetic inhibition in plants under low−Ca stress, whereas root application of Si significantly promoted root growth and development. Enhancing the photosynthetic capacity by foliar Si application is an effective strategy for ameliorating the growth inhibition of plants under low−Ca stress

A Comparative Study on the Nutrients, Mineral Elements, and Antioxidant Compounds in Different Types of Cruciferous Vegetables

Studies on the diversity within and among cabbage (Brassica oleracea L. var. capitata L.), cauliflower (Brassica oleracea var. botrytis), and Chinese cabbage (Brassica rapa L. ssp. pekinensis) variants are essential for the development of healthy diets. However, most studies on them have been limited to a single species, with little integrated analysis between them. In this study, the diversity within and among these species and varieties is assessed by determining the contents of 15 major characteristic nutrients, antioxidants, and minerals in 12 varieties of cabbage, 9 varieties of cauliflower, and 12 varieties of Chinese cabbage cultivated under the same conditions. The results show that there are significant differences in the compositional distributions of cabbage, cauliflower, and Chinese cabbage. Cabbage has the highest contents of soluble sugars (27.73 mg·kg−1 FW), flavonoids (5.90 mg·g−1 FW), and Fe (46.90 mg·kg−1 DW). Cauliflower is an ideal source of soluble protein (603.04 mg·kg−1 FW), polyphenols (1.53 mg·g−1 FW), glucosinolates (25.27 μmol·g−1 FW), and Cu (4.25 mg·kg−1 DW). Chinese cabbage is rich in vitamin C (0.45 mg·g−1 FW) and minerals (K, Ca, Mg, P, Mn, and Zn, at 9206.67 mg·kg−1 DW, 3297.00 mg·kg−1 DW, 3322.79 mg·kg−1 DW, 5614.78 mg·kg−1 DW, 15.36 mg·kg−1 DW, and 21.87 mg·kg−1 DW, respectively). There is a correlation between the quality, antioxidant properties, and minerals of the three species. In principal component analysis, a wide distribution of cabbage varieties and a high degree of overlap with the confidence ellipse of cauliflower are observed, indicating that certain cabbage varieties share compositional characteristics with cauliflower. These findings provide a reference for selecting varieties with higher nutritional value and antioxidant properties, as well as breeding new varieties

Additional file 1 of Comparative study of the quality indices, antioxidant substances, and mineral elements in different forms of cabbage

Supplementary Material