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Sodium chloride, at a concentration of 88 mol m −$ in half strength Hoagland nutrient solution, increased dry weight per unit area of Xanthium strumarium L. leaves by 19 %, and chlorophyll by 45 % compared to plants grown without added NaCl at ambient (350 µmol mol −") CO # concentration. Photosynthesis, per unit leaf area, was almost unaffected. Even so, over a 4-week period, growth (dry weight increment) was reduced in the salt treatment by 50 %. This could be ascribed to a large reduction in leaf area (60 %) and to an approx. 20 % increase in the rate of dark respiration (Rd).

Differences in the mechanism of ethylene emanation ofFicus sycomorus L. during various stages of the fruit development were investigated by enclosing the figs in jars. Two distinct patterns of ethylene emanation were found. Pattern a. in stages not capable of ripening, neither spontaneously nor as a result of physiological treatment (nonripening stages A and C), ethylene concentration in the jar increased linearly for a short time and then remained constant. Pattern b. in stages capable of ripening (ripening stages B, D, and E), the linear increase in ethylene concentration continued for the entire period of measurement. In nonripening stages, ethylene emanation stopped when ethylene concentration in the jar reached a constant value (0.6 pill at stage C). Aeration of the figs and the jar renewed ethylene emanation. CO2 concentration in the jar never exceeded 0.5%. Treatment of stage C figs with 0.6 to 10 pill exogenous ethylene caused immediate and complete cessation of ethylene emanation whereas the same treatment did not cause any change in rate of ethylene emanation from figs at the ripening stages B and D.

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