The absolute cyanide content of developing fruits was determined in Costa Rican wild lima beans (Phaseolus lunatus), oil flax (Linum usitatissimum), and bitter almonds (Prunus amygdalus). The cyanide potential (HCN-p) of the lima bean and the almond fruit began to increase shortly after anthesis and then stopped before fruit maturity. In contrast, the flax inflorescence had a higher HCN-p in absolute terms than the mature flax fruit. At all times of its development the bean fruit contained the monoglucosides linamarin and lotaustralin. The almond and the flax fruits contained, at anthesis, the monoglucosides prunasin, and linamarin and lotaustralin, respectively, while, at maturity, only the corresponding diglucosides amygdalin, and linustatin and neolinustatin, respectively, were present. bitter almond (Prunus amygdalus) from anthesis to the mature fruit. MATERIAL AND METHODS Source of Plant MaterialThe same collection of wild lima bean seed (Phaseolus lunatus L.) described by Frehner and Conn (6) Lima bean plants were grown in growth chambers from seeds in plastic pots (3 seeds per pot) using standard soil.Wooden rods were used to support the plants. The growth chambers were set to 10 h light (mixed incandescent and mercury vapor lamps) at 26°C and a RH of about 60%; at night the temperature was 1 8°C and the humidity about 80%. Flax was grown in growth chambers in groups of three plants per pot containing vermiculite. These chambers were set to 16 h light (mixed incandescent and fluorescent lamps) at 18°C; at night the temperature setting was 18°C. Humidity was not controlled in this experiment. All the plants were watered three times each week and received commercial liquid fertilizer once a week. The almond trees were neither watered nor fertilized. SamplingThe date ofanthesis ofindividual lima bean and flax flowers was recorded by inspection three times a week during a period of 5 weeks. Each time a small, dated tag was hung around stems bearing newly blossoming flowers; other 1 or 2 d old inflorescences not required for our experiments were removed so that only tagged fruits were allowed to develop. Mature and immature tagged fruits were removed from the parent plant, weighed, frozen in liquid N2, and lyophilized. Units consisting of whole pots were completely processed on the same day. Sufficiently developed lima bean fruits were divided into seeds and fruit walls prior to weighing (Fig. 1)

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Water stress increased mono-saccharides and decreased di-saccharides concentration in four field grown genotypes, regardless of their different drought susceptibility. Sandy, a USA genotype known for giving satisfying yields in droughty environments, outstood the other cultivars in terms of betaine and proline concentration in leaf tissues; these aminoacids are therefore considered responsible for the most negative ^s perceived in this cultivar.PV-curve technique revealed for Tullio, the drought susceptible Italian genotype, an osmotic adjustment of -0.63 MPa, four times greater than in Pandas, though this drought resistant cultivar showed a similar content in osmotically active substances; the authors therefore hypothesize an alternative mechanism in the response to water shortage in Tullio. K ey words: Triticum aestivum, osmotic adjustment, sugars, aminoacids.