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The morphological disorders of rice (Oryza sativa) seedling rootlets affected by salinity were studied in INCA-LP-10 cv., which has a certain salt-tolerance degree. Seeds were germinated in two saline concentrations, besides a separate control treatment just with water. After five days, rootlets were sampled, fixed to formaldehyde at 4 % and later processed until they were included in Epon resin. The semithin cuts were stained with blue toluidine. Longitudinal rootlet sections showed that salinity provoked morphological changes, according to NaCl concentrations employed, which mainly consisted of rootlet morphological changes and disorganized tissues, then opening large cavities among cell lines. [ABSTRACT FROM AUTHOR]

Qualitative changes of root tissues, as a result of high temperature (38°C for 1.5 h) were studied in two tomato (Lycopersicon esculentum Mill.) seedlings with different heat tolerance degrees. Seven days after rice seeds started to germinate, the heat treatment was applied to rootlets of each variety, which were isolated in pots containing water and later put on the stove for 1.5 h at 38deg;C, whereas the control treatment consisted of leaving the other group of rootlets under laboratory conditions while applying high temperature. Afterwards, rootlet samples were taken and processed through light microcopy, including epon resin and 2 µm-wide sections were cut and stained with toluidine blue, observed and photographed under a microscope with a digital camera. Longitudinal sections of rootlets showed that high temperature increased vacuole size and expanded cell walls, among other disorders; such changes became more evident at the heat stress tolerant variety. [ABSTRACT FROM AUTHOR]