The effect of arbuscular mycorrhizal fungi (AMF) inoculation and organic slow release fertilizer (OSRF) on photosynthesis, root phosphatase activity, nutrient acquisition, and growth of Ipomoea carnea N. von Jacquin ssp. fistulosa (K. Von Martinus ex J. Choisy) D. Austin (bush morning glory) was determined in a greenhouse study. The AMF treatments consisted of a commercial isolate of Glomus intraradices and a non-colonized (NonAMF) control. The OSRF was applied at 10, 30, and 100 % of the manufacturer's recommended rate. AMF plants had a higher net photosynthetic rate (PN), higher leaf elemental N, P, and K, and generally greater growth than NonAMF plants. Total colonization levels of AMF plants ranged from 27 % (100 % OSRF) to 79 % (30 % OSRF). Root acid phosphatase (ACP) and alkaline phosphatase (ALP) activities were generally higher in AMF than non-AMF plants. When compared to NonAMF at 100 % OSRF, AMF plants at 30 % OSRF had higher or comparable ACP and ALP activity, higher leaf elemental P, N, Fe, Cu, and Zn, and a greater PN (at the end of the experiment), leading to generally greater growth parameters with the lower fertility in AMF plants. We suggest that AMF increased nutrient acquisition from an organic fertilizer source by enhancing ACP and ALP activity thus facilitating P acquisition, increasing photosynthesis, and improving plant growth. and L. Amaya-Carpio ... [et al.].
Fifty-d-old poplar (Populus deltoides L.) plants were irrigated with 50-200 mM NaCl. 100 and 200 mM NaCl significantly reduced net photosynthetic rate, chlorophyll and carotenoid contents, leaf area, dry matter accumulation, and harvest index (HI) in all tested poplar clones (Bahar, S7C15, and WSL22). Clone S7C15 was more tolerant to salinity than the other clones. and M. Singh, M. Jain, R. C. Pant.
We compared the effects of salt-stresses (SS, 1: 1 molar ratio of NaCl to Na2SO4) and alkali-stresses (AS, 1: 1 molar ratio of NaHCO3 to Na2CO3) on the growth, photosynthesis, solute accumulation, and ion balance of barley seedlings, to elucidate the mechanism of AS (high-pH) damage to plants and the physiological adaptive mechanism of plants to AS. The effects of SS on the water content, root system activity, membrane permeability, and the content of photosynthetic pigments were much less than those of AS. However, AS damaged root function, photosynthetic pigments, and the membrane system, led to the severe reductions in water content, root system activity, content of photosynthetic pigments, and net photosynthetic rate, and a sharp increase in electrolyte leakage rate. Moreover, with salinity higher than 60 mM, Na+ content increased slowly under SS and sharply under AS. This indicates that high-pH caused by AS might interfere with control of Na+ uptake in roots and increase intracellular Na+ to a toxic level, which may be the main cause of some damage emerging under higher AS. Under SS, barley accumulated organic acids, Cl-, SO4 2-, and NO3 - to balance the massive influx of cations, the contribution of inorganic ions to ion balance was greater than that of organic acids. However, AS might inhibit absorptions of NO3 - and Cl-, enhance organic acid synthesis, and SO4 2- absorption to maintain intracellular ion balance and stable pH. and C.-W. Wang ... [et al.].
Plants of Brassica juncea L. cv. T-59 were supplied with 50 or 100 µM nickel (Ni50, Ni100) at 10 d after sowing (DAS), and sprayed with 28-homobrassinolide (HBR) at 20 DAS. The plants treated with Ni alone exhibited reduced growth, net photosynthetic rate, content of chlorophyll, and the activities of nitrate reductase (E.C.1.6.6.1) and carbonic anhydrase (E.C. 4.2.1.1) at observed 40 DAS, whereas, the contents of peroxidase (PER), catalase (CAT), and proline were increased. However, the spray of HBR partially neutralized the toxic effect of Ni on most of the parameters. Moreover, the treatment of HBR in association with either of the Ni concentration boosted the contents of PER and CAT in leaves and that of proline both in leaves and roots. and M. Masidur Alam ... [et al.].
Maize plant inbred lines, one Al-sensitive (B-73) and two Al-tolerant (F-2 and L-2039), were grown hydroponically in the presence of 200 µM Al. After 13 d of growth, root and shoot lengths, photosystem 2 (PS2) activity, chlorophyll (Chl) content, 5-aminolevulinic acid (5-ALA) synthesis rate, chlorophyllase (Chlase) activity, and N, Mg, Fe, and Mn contents in leaves were determined. PS2 activity and Chl content were most severely affected by Al in B-73, but F-2 was almost unaffected. This was in accordance with Al-accumulation in the plants. The observed changes in B-73 coincided with 5-ALA synthesis inhibition, Chlase activation, and leaf deprivation of Fe and Mg. In Al-treated L-2039 plants, the leaf Mg and Mn contents were decreased. Also, an excessive Chlase activation was found in Al-treated L-2039, without a substantial Chl loss. This may indicate the activation of different enzyme pools in tolerant and sensitive genotypes under low-stress conditions. and N. Mihailovic, G. Drazic, Z. Vucinic.
The effects of 0, 2.5, 5.0, and 10.0 mg(Cd2+) m-3 [Cd(NO3)2×4 H2O] and 0 and 10.0 mg m-3 gibberellin on certain parameters of photosynthesis and growth in soybean (Glycine max L. cv. Pershing) plants were studied. With increasing Cd2+ concentration in the Hoagland nutrient solution, the contents of chlorophyll and CO2 compensation concentration decreased. The addition of 10 mg m-3 gibberellin reduced the negative effects of Cd2+ in shoot and root growth. With increasing of Cd2+ concentration in the culture medium, the dry matter production in both the roots and shoots decreased as shown by the decline in growth rate (PGR), net assimilation rate (NAR), and leaf area ratio. The addition of gibberellin caused a partial elimination of the Cd effects on the roots and shoots and the PGR and NAR and it increased leaf area and length of stem. and M. Ghorbanli, S. Hadad Kaveh, M. Farzami Sepehr.
Walnut (Juglans regia L.) plantlets were incubated during micropropagation in standard vessels (quasi confmed vessels) or in aerated vessels flushed with 360 or 20 000 cm^(C02) under irradiances of 70 (LI) and 250 (HI) pmol m"^ s'*. Plantlet morphology was strongly affected by the environment; leaf surface was increased, but shoot elongation and number of stems were reduced after increasing the irradiance of culture. Gross photosynthesis (Pq) capacity measured by using the •®02 isotope and mass-spectrometry techniques was increased by increasing photosynthetic photon flux (PPF) and CO2 concentration. Plantlets exhibited a potential for photorespiratory activity and Mehler-type reaction and a high rate of mitochondrial respiration in all vessel types and irradiances. When a long-term HI was applied, gas exchange rates (Pq and O2 uptake) were reduced in most of the vessel and PPF conditions, except in quasi confmed vessels. Under all the growth conditions, net photosynthetic rate (P^) was zero or slightly positive and the dry matter accumulation was very similar. Changes in O2 exchange, growth rate or enzyme activities linked to carbon fixation that were induced by changes in PFD and CO2 concentration showed that the photosynthetic characteristics of plantlets were typical for hetero-mixotrophic tissues.
Two cultivars of common buckwheat (Fagopyrum esculentum), Pyra and Siva, were exposed to three treatments: water deficit (WD), foliar spraying by selenium (as Na2SeO4) (Se), and the combination of both. In WD-plants the stomatal conductance (gs) was significantly lower, while WD+Se-plants of Siva had significantly higher gs. None of the treatments resulted in significant differences of potential photochemical efficiency of photosystem 2 (PS2). A significantly higher actual photochemical efficiency of PS2 was obtained in Siva WD-plants and in Pyra Se-and WD-plants which was possibly due to improvement of plant water management during treatment. A significant interaction was observed between the effects of WD and Se on respiratory potential in Pyra. WD, Se, and the WD+Se combination resulted in shorter Pyra and Siva plants, with a reduced number of nodes. WD slightly negatively affected the yield per plant. The yield was highest in plants exposed to Se only. In Siva the number of seeds was triple while the average seed mass remained unchanged. and N. Tadina ... [et al.].
Seedlings of chile ancho pepper were grown in pots containing a pasteurized mixture of sand and a low phosphorus (P) sandy loam soil, and either inoculated (VAM) or not inoculated (NVAM) with the endomycorrhizal fungus Glomus intraradices. Long Ashton nutrient solution (LANS) was modified to supply P to the seedlings at 0, 11, and 44 g(P) m-3 (P0, P11, P44, respectively). Low P depressed net photosynthetic rate (PN), stomatal conductance (gs), phosphorus use efficiency (PN/P), and internal CO2 concentration (Ci). The mycorrhiza alleviated low P effects by increasing PN, gs, PN/P, and decreasing Ci. At P0, Ci of NVAM plants was equal to or higher than that of VAM plants, suggesting nonstomatal inhibition of photosynthesis. Gas exchange of VAM plants at P0 was similar to that of NVAM plants at P11. Endomycorrhiza increased leaf number, leaf area, shoot, root and fruit mass at P0 and P11 compared to NVAM plants. Reproductive growth was enhanced by 450 % in mycorrhizal plants at P44. Root colonization (arbuscules, vesicles, internal and extraradical hyphae development) was higher at lower P concentrations, while sporulation was unaffected. The enhanced growth and gas exchange of mycorrhizal plants was in part due to greater uptake of P and greater extraradical hyphae development. and L. Aguilera-Gomez ... [et al.].
The possibility of simultaneously ušed chlorophyll (Chl) synthesis precursor (glutamic acid) and metal chelator (2,2'-dipyridyl) as a photodynamic inhibitor of the chlorophyll synthesis was studied. Wheat {Triticum aestivum L.) and vegetable marrow {Cucurbita moschata Duch.) leaves were treated with 2,2'-dipyridyl (2,2'- DP), and 2,2'-DP along with glutamic acid which increased the protochlorophyllide (Pchlide) content in the vegetable marrow plants to a higher extent. An irradiation of the treated leaves caused an inhibition of Pchlide reduction which was more notable in those of the dicotyledonous vegetable marrow plant.