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Nitrogen nutrition and the level of Crassulacean acid metabolism in Kalanchoë lateritia Engl.
Author(s) -
SANTOS I.,
SALEMA R.
Publication year - 1991
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1991.tb01506.x
Subject(s) - crassulacean acid metabolism , titratable acid , nitrogen , photosynthesis , chlorophyll , chemistry , rubisco , nitrate , starch , botany , horticulture , chlorophyll a , zoology , biology , food science , organic chemistry
. The influence of different nitrogen levels was studied in the CAM facultative Kalanchoë lateritia by watering some plants with Hoagland's solution (which contains, besides other ions, NO 3 − = 14.47mol m −3 and NH 4 + = 1.04mol m −3 ; N group), and others with the same solution but with combined nitrogen concentration reduced to either one fifth (NO 3 − = 2.894mol m −3 and NH 4 + = 0.208mol m −3 ; N/5 group) or one tenth (NO 3 − = 1.447mol m −3 and NH 4 + = 0.104mol m‐ 3 ;N/10 group). The influence of the three nitrogen levels on CAM expression was assessed through activities of PEP‐Case, PPD and RuBisCo, diurnal fluctuation of titratable acidity, mesophyll succulence, soluble protein, chlorophyll, nitrate, starch contents, pattern of nocturnal CO 2 exchange and electron microscopy. CAM photosynthesis was more intense in N/5 plants which also had the highest Sm value. The activity of RuBisCo showed no significant differences in the three situations (expressed on chlorophyll basis) whereas both PEP‐Case and PPD had higher values in N/5” plants. Chlorophyll and soluble protein were more abundant in the N plants followed by N/5 and N/10 plants. Nitrate was higher in N plants and starch content in N/5 plants. IRGA determination of CO 2 nocturnal uptake showed that N/5 plants began CO 2 capture earlier and at a more intense rate and for a longer period than plants from other groups also having a daily variation of titratable acidity (97.71 ± 10.8 μeq. G −1 f.w.) indicative of performing strong CAM. Electron microscope morphometric analysis revealed larger chloroplasts in N plants and smaller in N/10 plants, with starch fractional volume higher in N/5 plants, correlating with more intense CAM activity of these plants.