At the level of the whole canopy, the effects of water deficits on cotton leaf area expansion and absorption of Water stress may reduce leaf net photosynthetic carbon assimilaphotosynthetically active radiation are easily measured tion (A N ) through both stomatal effects, which reduce the leaf internal and have been well documented (Turner et al., 1986; CO 2 concentration (C i ), and nonstomatal effects, which result in re- Puech-Suanzes et al., 1989;Ball et al., 1994). Water duced A N at a given level of C i . However, the leaf gas exchange stress also affects the efficiency with which absorbed techniques used to calculate C i are susceptible to important artifacts radiation is used to carry out carbon fixation at the leaf when applied to water-stressed leaves, making such C i estimates unrelevel, and the mechanisms by which this occurs have tosynthetic photon flux density; R D , rate of leaf respiration in the dark; Published in Crop Sci. 45:2374-2382(2005. Crop Physiology and Metabolism RSWC, relative soil water content; v C , velocity of the carboxylation reaction of RubisCO; v O , velocity of the oxygenation reaction of Ru-

Plant growth, yield, and fruit quality of two strawberries (Fragaria ×ananassa Duch.)—`Chandler' and `Sweet Charlie'—grown under high tunnels (HTs) were compared with that of field plants during 2002–03 and 2003–04 growing seasons. Plug plants were planted in mid-October 2002 and mid-September 2003 on raised beds covered with black polyethylene mulch. Microclimate of the HTs protected strawberry crowns from winter damage and advanced fruit production 5 weeks earlier than that of plants grown under field conditions. From December to February, average minimum and maximum crown temperatures under the HTs were 5 and 12 °C warmer than those of the field crowns, respectively. The earliest HT fruit were harvested on 7 Apr. 2003 and 11 Mar. 2004. Yield and fruit quality under the HTs were superior to that of field-grown plants. HT plants, especially `Sweet Charlie', bloomed earlier than did field plants, but `Chandler' produced higher yield than `Sweet Charlie' late in the season. Larger fruit with higher soluble solids concentration (SSC) were produced inside the HTs than outside. HT `Sweet Charlie' fruit were sweeter than `Chandler' fruit, but `Chandler' produced larger fruit. Larger leaf area, greater number of leaves and shoot biomass, more branch-crowns, and fewer runners were developed under HTs than field conditions. Total leaf area, leaf production, total shoot biomass, and number of branch-crowns of HT `Chandler' were greater than HT `Sweet Charlie'. Results of this study indicate that strawberry plants under HTs were not only precocious, but also produced higher yields and superior quality to that of field plants. HT conditions suppressed runner growth, but enhanced branch-crown development.

Estimates of thylakoid electron transport rates (J(e)) from chlorophyll fluorometry are often used in combination with leaf gas exchange measurements to provide detailed information about photosynthetic activity of leaves in situ. Estimating J(e) requires accurate determination of the quantum efficiency of Photosystem II (Phi(P)), which in turn requires momentary light saturation of the Photosystem II light harvesting complex to induce the maximum fluorescence signal (F(M)'). In practice, full saturation is often difficult to achieve, especially when incident photosynthetic photon flux density (Q) is high and energy is effectively dissipated by non-photochemical quenching. In the present work, a method for estimating the true F(M)' under high Q was developed, using multiple light pulses of varying intensity (Q'). The form of the expected relationship between the apparent F(M)' and Q' was derived from theoretical considerations. This allowed the true F(M)' at infinite Q' to be estimated from linear regression. Using a commercially available leaf gas exchange/ chlorophyll fluorescence measurement system, J(e) was compared to gross photosynthetic CO(2) assimilation (A(G)) under conditions where the relationship between J(e) and A(G) was expected to be linear. Both in C(4) leaves (Zea mays) in ambient air and also in C(3) leaves (Gossypium hirsutum) under non-photorespiratory conditions the apparent ratio between J(e) and A(G) declined at high Q when Phi(P) was calculated from F(M)' measured simply using the highest available saturating pulse intensity. When F(M)' was determined using the multiple pulse / linear regression technique, the expected relationship between J(e) and A(G) at high Q was restored, indicating that the Phi(P) estimate was improved. This method of determining F(M)' should prove useful for verifying when saturating pulse intensities are sufficient, and for accurately determining Phi(P) when they are not.

No abstract

With the progresses of oilseed industry, an important interest is currently being focused on exploiting novel and underutilized sources for vegetable oils. Being so far the less studied part in fig fruits, seeds separated from four fig cultivars were assessed for their oil content, fatty acids identification, total phenolics and invitro antioxidant analysis. A one-way Anova yielded statistically significant differences for all parameters, with the exception of pentadecylic, margaric and arachidic acids besides the total saturated fatty acids. Fig seeds presented a yellow colored oil, of which the content ranged from 21.54 ± 1.71 to 28.52 ± 0.62%. Gas liquid chromatography analysis of the seed oil showed high percentages of linolenic acid in the four cultivars ranging from 38.43 ± 0.01 to 43.57 ± 0.04, followed by linoleic acid (28.9 ± 0.06–34.5 ± 0.04%). Palmitic acid and stearic acid were the dominating saturated fatty acids in all samples, where the amounts were in the range from 8.54 ± 0.04 to 9.05 ± 0.06% and from 2.59 ± 0.13 to 3.3% respectively. The efficiency of the desaturation from oleic acid to linoleic acid estimated within desaturation pathway, was higher among all cultivars than the efficiency of the desaturation from linoleic acid to linolenic acid. This explains the large increase of 18:3 concentration in all samples. The local cultivar ‘C11A21’ exhibited the highest total unsaturated fatty acids and the lowest level of saturated fatty acids, while the cultivar ‘White Adriatic’ combined the most relevant phenolics content, antioxidant activity and half maximum inhibitory concentration. All sampled oil possessed an important phenolics content that displayed variable levels of antioxidant activity. The objective of this study is to bring new data on the biochemical attributes of fig seeds as a new source oil that can be used for nutritional, pharmaceutical and cosmetic purposes.

No abstract

No abstract

No abstract