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Irrigation water high in alkalinity can severely compromise the growth and marketability of ornamental plants. In the present study we investigated the response of lisianthus to increased calcium (Ca) when irrigated with solutions containing high levels of bicarbonate (HCO3−)-induced alkalinity. Alkalinity in irrigation water reduced the growth of lisianthus; however, plants supplemented with an increased concentration of Ca at alkalinity levels from 4 to 7 meq·L−1 of HCO3– exhibited improved growth and dry mass (DM) accumulation or were not detrimentally affected, demonstrating that Ca contributes to the increase of the tolerance of lisianthus to alkalinity. Supplementary Ca did maintain a high stomatal conductance (gS) and transpiration rate when alkalinity was at 4 meq·L−1, which explained the lower water potential in young leaves. Plants irrigated with solutions containing supplementary Ca had higher total DM, which was associated with a higher gS; however, when conductance was higher than 0.280 cm·s−1, like in plants with no supplementary Ca, DM tended to decrease. At a typical Ca concentration, there was a disruption on stomata functioning as gS and transpiration rate increased, which was associated with a reduction in shoot potassium (K). Calcium ameliorated the uptake of K when alkalinity was 4 meq·L−1 by allowing a less marked reduction in shoot K concentration. Chlorophyll was reduced by increasing alkalinity as a result of a decrease in shoot iron (Fe); however, supplementary Ca also contributed in increasing plant tolerance to alkalinity at 4 meq·L−1 by sustaining a high shoot Fe concentration. Supplementary Ca increased catalase and peroxidase activities, indicating that lisianthus responded to the stress by enhancing the activity of these enzymes to reduce oxidative damage.

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The production of gladiolus cut flowers of good quality largely relies on corm reserves and size; however, little attention has been paid to the understanding of the nutrient requirements for optimum quality of such organs. In the present study, it was evaluated the dynamics of biomass and the content of macronutrients in the mother and daughter corms as affected by the initial size of the mother corm. The biomass of the mother corm decreased after the transplant whereas, after flower harvest, that of the daughter corm increased. The content of N, K, Mg and S had a similar tendency as that of biomass, however, once the daughter corm appeared there was an increase in the content of these elements. A portion of P, Ca, Mg and S present in the mother corm was remobilized towards the daughter corm, nonetheless, in order to meet its demands, the daughter corm has to be supplemented through fertilization with 63.6, 52.9, y 38.0 kg ha-1 N, 9.2, 8.4 y 5.8 kg ha-1 P and 11.2, 11.3, and 7.7 kg ha-1 K for daughter corms developed from mother corms of 3.8 g (3.5 cm diameter), 2.5 g (3.0 cm diameter) and 1.8 g (2.5 cm diameter), respectively. Calcium has to be supplemented at 2.9-5.0 kg ha-1 , whereas Mg and S at 0.9 and 1.6 kg ha-1, respectively.