The net photosynthetic rate (PN), intercellular CO2 concentration (Ci), stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE), and leaf biomass production of four American flue-cured tobacco (Nicotiana tabacum L.) cultivars K 326, K 358, and Speight G 28 were compared with three local Indian cultivars 16/103, Special FCV, and PCT-7, during 1994 and 1995 crop seasons under irrigated and rainfed production systems (Northern light soils, NLS, and Karnataka light soils, KLS) in India. By comparison, the American tobacco cv. K 326 showed the highest PN and gs. A positive correlation was found between PN and biomass production in all the varieties tested (r = 0.55 in NLS and 0.73 in KLS). The American cultivars were superior than the local cultivars in their biomass production and PN under Indian farming conditions. and P. Srinivas, B. N. Smith, P. M. Swamy.
Dry matter (DM) of olive fruit (cv. Leccino) constantly increased from fruit-set (mid-June) to the end of October. The oil content increased rapidly from the beginning of August, about 40-50 d after full bloom (AFB), to the end of October. As the oil content increased, the saccharide content decreased. On a DM basis, fruit dark respiration rate (RD) and stomatal conductance (Gs) were high soon after fruit-set, then strongly decreased. Gross photosynthetic rate (PG) in full sunlight was high in the first 3 weeks after fruit-set, when the chlorophyll (Chl) content and the ratio between fruit surface area and volume were high, then it progressively decreased. The fruit intercellular CO2 concentration (Ci) was always relatively high, particularly from September onwards. The PG increased following the increase of irradiance (I). The daily PG trend was similar to the I and temperature trends, showing the maximum values at 14:00 h. For a large part of the fruit growing period, during daylight, the CO2 intake by a fruit permitted the reassimilation of a large part (40-80%) of the CO2 produced by RD. The stomata in the first stages of fruit growth were oval and surrounded by guard cells, two months later they lost their shape and were covered by wax. The reduction in fruit PG during fruit growth could be connected to the reduction of the ratio between fruit surface area and fruit volume and the cellular differentiation, whereas the constant high Ci seems to exclude the influence of Gs decrease. Even if olive fruit is highly heterotrophic organ, its photosynthesis can considerably reduce the use of assimilates for respiration and favour fruit maintenance and growth. and P. Proietti, F. Famiani, A. Tombesi.
From the beginning of olive leaf yellowing to leaf fall (1/3 months), there was a general trend from anabolism to catabolism. Rates of net photosynthesis (PN) and respiration, areal dry mass, and contents of pigments, particularly of chlorophyll (Chl) a, starch, and above all nitrogen (N) decreased. The detachment force decreased dramatically only in completely chlorotic leaves. Chl a : b ratio only declined in the last 10-20 d of senescence, when the total Chl contents diminished by about 70 %, after which the N content, PN, and efficiency of the photochemical energy conversion of the remaining Chl and N dramatically declined. Consequently, for most of the natural course of senescence PN remained relatively high. The reduction in PN was associated with the decreases in transpiration rate (E) and stomatal conductance (gs), but these probably did not cause the decline of PN. The recycling of saccharide compounds was low, while 50 % of the total N on a leaf area basis was relocated back before leaf abscission, changing the leaf from a carbon source to a mineral source. Therefore, considering that senescing leaves in olive trees contribute to carbon gain and allow the recycling of resources, it is essential to prevent the premature leaf abscission by avoiding deficits of water and mineral nutrients and by using pruning and training systems that allow good irradiation of all leaves in the crown.
Short-term responses of four carrot (Daucus carota) cultivars: Cascade, Caro Choice (CC), Oranza, and Red Core Chantenay (RCC) to CO2 concentrations (Ca) were studied in a controlled environment. Leaf net photosynthetic rate (PN), intercellular CO2 (Ci), stomatal conductance (gs), and transpiration rate (E) were measured at Ca from 50 to 1 050 μmol mol-1. The cultivars responded similarly to Ca and did not differ in all the variables measured. The PN increased with Ca until saturation at 650 μmol mol-1 (Ci= 350-400 μmol mol-1), thereafter PN increased slightly. On average, increasing Ca from 350 to 650 and from 350 to 1 050 μmol mol-1 increased PN by 43 and 52 %, respectively. The PNvs.Ci curves were fitted to a non-rectangular hyperbola model. The cultivars did not differ in the parameters estimated from the model. Carboxylation efficiencies ranged from 68 to 91 μmol m-2 s-1 and maximum PN were 15.50, 13.52, 13.31, and 14.96 μmol m-2 s-1 for Cascade, CC, Oranza, and RCC, respectively. Dark respiration rate varied from 2.80 μmol m-2 s-1 for Oranza to 3.96 μmol m-2 s-1 for Cascade and the CO2 compensation concentration was between 42 and 46 μmol mol-1. The gs and E increased to a peak at Ca= 350 μmol mol-1 and then decreased by 17 and 15 %, respectively when Ca was increased to 650 μmol mol-1. An increase from 350 to 1 050 μmol mol-1 reduced gs and E by 53 and 47 %, respectively. Changes in gs and PN maintained the Ci:Ca ratio. The water use efficiency increased linearly with Ca due to increases in PN in addition to the decline in E at high Ca. Hence CO2 enrichment increases PN and decreases gs, and can improve carrot productivity and water conservation. and S. Kyei-Boahen ... [et al.].
Net photosynthetic rate (PN) and dark respiration rate (RD) were measured in Vitis vinifera L. cvs. Dimiat 4/24 (23rd subculture), Dimiat 4/38 (22nd subculture), and Italian Riesling 3/47 (22nd subculture) on days 3, 2, and 1 (1st series) before transfer from the in vitro culture and on days 14, 15, 16 (2nd series) and 28, 29, 30 (3rd series) after the transfer. PN of in vitro and ex vitro plants was strongly affected by irradiance. PN and RD of in vitro plantlets were lower and transpiration rate (E) was higher compared to those of ex vitro plantlets. PN, RD, and E changed in the course of acclimation. and T. Slavtcheva, V. Dimitrova.
Three winter wheat (Triticum aestivum L.) cultivars, representatives of those widely cultivated in Beijing over the past six decades, were grown in the same environmental conditions. Net photosynthetic rate (PN) per unit leaf area and instantaneous water use efficiency (WUE) of flag leaves increased with elevated CO2 concentration. With an increase in CO2 concentration from 360 to 720 µmol mol-1, PN and WUE of Jingdong 8 (released in 1990s and having the highest yield) increased by 173 and 81 %, while those of Nongda 139 (released in 1970s) increased by 88 and 66 %, and Yanda 1817 (released in 1945, with lowest yield) by 76 and 65 %. Jingdong 8 had the highest PN and WUE values under high CO2 concentration, but Yanda 1817 showed the lowest PN. Stomatal conductance (gs) of Nongda 139 and Yanda 1817 declined with increasing CO2 concentration, but gs of Jingdong 8 firstly went down and then up as the CO2 concentration further increased. Intercellular CO2 concentration (Ci) of Jingdong 8 and Nongda 139 increased when CO2 concentration elevated, while that of Yanda 139 increased at the first stage and then declined. Jingdong 8 had the lowest Ci of the three wheat cultivars, and Yanda 1817 had the highest Ci value under lower CO2 concentrations. However, Jingdong 8 had the highest PN and lowest Ci at the highest CO2 concentration which indicates that its photosynthetic potential may be high. and H. Q. Liu ... [et al.].
Effect of NaCl (electrical conductivity of 0, 5, 10, 15, and 20 dS m-1) on growth, gas exchange, and ion uptake in two Ziziphus species (Z. rotundifolia and Z. nummularia) differing in salt tolerance was studied. At 30 and 45 d after first leaf initiation, the dry mass of shoot and leaves, and rates of net photosynthesis (PN) and transpiration (E) decreased significantly with increasing NaCl concentration whereas membrane injury and accumulation of proline increased. The sodium content was highest in the roots of Z. rotundifolia and in the leaves of Z. nummularia. Potassium content did not differ much in the roots but it was significantly higher in the leaves of Z. rotundifolia at 30 and 45 d of observations. Thus both these species were tolerant to salinity but at high salinity Z. rotundifolia performed better owing to its higher PN and E, restricted translocation of sodium from root to leaves, and larger accumulation of potassium in the leaves. and N. K. Gupta ... [et al.].
Gas exchange, photochemical efficiency, and leaf water potential (Ψl) of Salix matsudana (non-indigenous species), S. microstachya and S. gordejevii (indigenous species) were studied in Hunshandak Sandland, China. Ψl of all the three species decreased from 06:00 to 12:00, and increased afterwards. S. matsudana showed higher values of Ψl than others. Net photosynthetic rate (PN) and stomatal conductance (gs) of S. matsudana were the lowest among all, with the maximum PN at 10:00 being 75% of that of S. gordejevii. Compared with the indigenous species, the non-indigenous S. matsudana had also lower transpiration rate (E) and water use efficiency (WUE). The values of Fv/Fm in all the species were lower from 06:00 to 14:00 than those after 14:00, indicating an obvious depression in photochemical efficiency of photosystem 2 in both non-indigenous and native species. However, it was much more depressed in S. matsudana, the non-indigenous tree. PN was positively correlated to gs and negatively related to Ψl. The relationship between gs and vapour pressure difference (VPD) was exponential, while negative linear correlation was found between gs and Ψl. and M. Z. Liu ... [et al.].
Net photosynthetic rate (PN), transpiration rate (E), water use efficiency (WUE), stomatal conductance (gs), and stomatal limitation (Ls) were investigated in two Syringa species. The saturation irradiance (SI) was 400 µmol m-2s-1 for S. pinnatifolia and 1 700 µmol m-2s-1 for S. oblata. Compared with S. oblata, S. pinnatifolia had extremely low gs. Unlike S. oblata, the maximal photosynthetic rate (Pmax) in S. pinnatifoliaoccurred around 08:00 and then fell down, indicating this species was sensitive to higher temperature and high photosynthetic photon flux density. However, such phenomenon was interrupted by the leaf development rhythms before summer. A relatively lower PN together with a lower leaf area and shoot growth showed the capacity for carbon assimilation was poorer in S. pinnatifolia. and H. X. Cui ... [et al.].
The genetic basis of stomatal conductance (gs), net photosynthetic rate (PN), and transpiration rate (E) was explored by using a wheat doubled haploid population from a cross of Hanxuan10 and Lumai 14. The above three traits were evaluated in wheat flag leaves at 10, 20, 30 days after anthesis under drought stress (DS) and well-watered (WW), and quantitative trait loci (QTL) were analyzed. Expression of the traits during the grain filling stage showed downward trends under both conditions, but expression of three phenotypes were stronger under WW than those under DS. Extremely significant positive correlations were established among the traits at all growth stages under both conditions. A total of 18 additive QTLs for those traits were identified on 10 chromosomes. Among them, two batches of nine additive QTLs were associated with the target traits under DS and WW, respectively. Two additive QTLs for gs and E, two for gs and PN, six for gs, PN, and E clustered at the same or near the region (colocation) of chromosomes 4A, 2B, and 7B, respectively. This provided genetic basis for close phenotype correlations among gs, PN, and E. Furthermore, QTLs for gs, PN, and E near Xgwm577 and Xgwm611 located on 7B chromosome were linked to previously reported QTLs regulating a SPAD value and the chlorophyll a/b ratio under dark-induced condition. This finding indicated that these QTLs on 7B chromosome might be involved in the process of wheat leaf senescence., S. G. Wang, S. S. Jia, D. Z. Sun, H. Y. Wang, F. F. Dong, H. X. Ma, R. L. Jing, G. Ma., and Obsahuje bibliografii