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The present work was conducted with the objective of studying the behavior of growth, the net photosynthetic rate, stomatal conductance, hydraulic conductivity of roots and leaf water, osmotic and turgor potencials in seedlins of tomato plants submitted to progressive increase to NaCl in the medium, for this seedlins of tomato plants (Solanum lycopersicum L. Cv. Amalia) were submitted to seven different treatments: control (C) plants were maintained in nutrient solution without NaCl; adapted plants (PC) were submitted to progressive increase of 25 mM of NaCl each four days in nutritious solution, in the others treatments were submitted to 25, 50, 75, 100 and 125 mM of NaCl during all experimental period. The inhibition of dry mass accumulation in root system and stem was observed in non adapted plants, while the leaf dry mass and leaf area were affected in all treatments in relation to control plants. Saline stress decreased net photosynthetic rate, stomatal conductance and root hydraulic conductivity in non adapted plants, however, PC plants showed good osmotic adjustment, which enabled them to maintain leaf pressure potential, decreased leaf water potential and osmotic potential at full turgor while the biologic activity was appropriate. [ABSTRACT FROM AUTHOR]

In order to study the ecophysiological relations that affect the growth of B. decumbens in monocrop (MO) and associated withZ. leucocephala (AS), evaluations of photosynthetic active radiation (PAR), assimilation (A) stomatic conductance (Gs), transpiration (E), relative humidity (RH), water potential (0h), differential of steam pressure (DSP) and leaf area index (LAI) were made in a tropical humid forest zone. The evaluations were made 5,10 and 22 days after grazing under both conditions (MO and AS). The most positive values of 0h (P<0,05) were found in AS, as well as the lowest values of PAR (P<0,05) in all the evaluated dates. RH and DSP did not show differences (P 0,05). The gas exchange parameters (E, Gs and A) showed significantly higher values in MO (P<0,05) in all dates. LAI was higher in MO after 10 and 22 days of evaluation. Due to the limitation of the photosynthetic capacity exerted by the light decrease on the grass, that PAR is concluded to be the most important factor that determine growth and development of B. decumbens in AS. [ABSTRACT FROM AUTHOR]

This research work was aimed at determining the effect of high temperatures on some growth variables and gas exchange in tomato plants of Amalia cv. Plants were grown in pots containing silica sand, which were put in trays adding Hoagland's nutrient solution to them. Treatments consisted of a control having a temperature of 25 gC during the day and 18 gC in the dark period, another treatment in which day and night temperatures increased 5 gC every four days up to 40 with 33 gC and a variant where plants were subjected to a heat shock of 40/33 gC day/night respectively for a period of four days. Once treatment application was concluded, plants were placed under the same conditions of the control treatment for 12 days, to evaluate their recovery. Evaluations on biomass, stomatal conductance and CO2 assimilation rate were recorded at the end of every period of heat treatment and recovery. Data analysis made evident a depressive effect of different variables evaluated when increasing environmental temperature; such effect was not eliminated in some indicators after the recovery period. [ABSTRACT FROM AUTHOR]