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In this paper, we propose a model for information propagation in a population based on cellular automata. Different to what is commonly used in the models of the area, instead of a binary level for the information, individuals have a level of knowledge. Moreover, the population can have a marketing campaign to help to spread the information with a certain limit due to the consideration of marketing rejection in the model. Numerical simulations show that these campaigns must be wisely set in order to not saturate the population and decrease the marketing balance due to the rejection. The simulation data is statistically analyzed by using principal component analysis in order to identify the most relevant variables for the model output. The conclusion is that dealing with this rejection is difficult, as well as choosing the percentage of the population which will receive the marketing, and along with the weight for the word-of-mouth were the most important variables of the model according to the simulations and the principal component analysis.

Desiccation tolerance (DT) in vegetative tissues is not a common ability, especially in Angiosperms. Barbacenia genus is distributed in tropical seasonally dry environments, such as rock outcrops, in South America. Some of the Barbacenia species are described as DT and are able to tolerate drastic water loss of their tissues during the desiccation process and to reestablish their metabolism after rehydration. In order to better understand this ability, we evaluated aspects related to leaf water status, gas exchange, photosynthetic pigments content and chlorophyll a fluorescence of B. graminifolia, during 32 days of water deprivation followed by rehydration. Carbon assimilation (A) remained active until the 24th day, when volumetric soil moisture was below 10%. Leaf relative water content (RWC) remained constant during 28 days of water withholding, decreasing significantly after this period, followed by the lowest gas exchange parameters and maximum quantum efficiency of photosystem II (Fv/Fm), and the highest degradation rates of chlorophyll and carotenoids in the course of the desiccation period. After rehydration, RWC was rapidly recovered, as well as Fv/Fm and photosynthetic parameters. This time frame was not enough for total recovery of A rates due, probably, to the slow restoration of chlorophyll a content. We classify, therefore, the species as a resurrection plant. Despite the similar decrease of photosynthetic rates found in other DT species before reaching the desiccated state, B. graminifolia maintains CO2 assimilation even under low soil water availability (10%) as physiological strategy when submitted to severe water deficit.

Seasonal changes in vegetative growth, leaf gas exchanges, carbon isotope discrimination (Δ) and carbohydrate status were monitored in de-fruited coffee trees (Coffea arabica L.) grown in the field, from October 1998 through September 1999, in Vicosa (20°45′S, 42°15′W, 650 m a.s.l.), southeastern Brazil. Of the total growth over the 12-month study period, 78% occurred in the warm, rainy season (October–March), and 22% during the cool, dry season (April–September). Throughout the active growth period, the rate of net carbon assimilation (A) averaged 8.6 μmol m−2 s−1, against 3.4 μmol m−2 s−1 during the period of reduced growth. In the active period, growth, unlike A or Δ, was strongly negatively correlated with air temperature. In contrast, growth and A were both correlated positively, and Δ correlated negatively, with air temperature during the reduced growth period. However, the depressions of A and growth might have simply run in parallel, without any causal relationship. Changes in A appeared to be largely due to stomatal limitations in the active growing season, with non-stomatal ones prevailing in the slow growth period. Foliar carbohydrates seemed not to have contributed appreciably to changes in growth rates and photosynthesis.