Soybean (Glycine max Merrill) and maize (Zea mays L.) plants were exposed for 5 to 48 h to the herbicide diquat under "white light" (WL) or far-red radiation (FR) (photon fluence rate of 30 µmol m^-2 s^-1). The WL enhanced diquat effect on chlorophyll content in soybean plants, while FR had the same effects on maize plants. After 5 h, diquat increased the content of polypeptides bound to light-harvesting proteins in both plants.

Two approaches were used to detect variability within 23 pea cultivars. Eight random amplified polymorphic DNA (RAPD) primers produced 163 bands (114 polymorphic), whereas five isoenzyme systems produced 25 bands (20 polymorphic). Both methods provided good results in finger-printing and identified all cultivars tested. Genetic similarity analysis (UPGMA) gave different results from RAPD and isoenzyme data. This could reflect different properties of both marker types. These data were also analysed using the bootstrap method, which supported the idea of one common progenitor of cultivated peas.

The role of potassium nutrition in microtuber production was investigated in two potato cultivars belonging to different maturity groups. Alterations were made in Murashige and Skoog (MS) medium to obtain seven concentrations of potassium (10, 15, 20, 25, 30, 35 and 40 mM), and their effects were studied on microtuber number, microtuber mass and harvest index. In late cultivar Kufri Sindhuri, an increase in potassium concentration beyond 25 mM decreased the number of microtubers. Whereas, potassium did not show any inhibitory effect on microtuber number in early cultivar Kufri Ashoka. Potassium showed promoting effect on microtuber mass in both the cultivars. Maximum microtuber mass and harvest index were observed when the medium was supplemented with 40 mM potassium. Therefore, large size potato microtubers amenable to direct field planting can be induced in MS medium containing 40 mM potassium.

Growth of Sesbania rostrata was decreased gradually with increase in root medium salinity (mixed salts or NaCl alone). Soil moisture or anoxia did not affect plant growth significantly. Higher K⁺/Na⁺ ratios in plant tissues compared to those in the root medium were found under different salinities. This indicated a high K⁺-Na⁺ selectivity, a characteristic generally considered unique to halophytes. S. rostrata is moderately salt tolerant and may be utilized as forage crop and green manure on saline land.

French bean (Phaseolus vulgaris L. cv. Contender) plants at five developmental stages (4, 8, 12, 16 and 20 d after sowing) were exposed to one of three treatments: 1 - 25 °C (control), 2 - exposure to chilling at 10 °C only for 2 d prior to sampling, and 3 - long-term exposure to chilling at 10 °C. Short- and long-term chilling decreased plant growth. Higher concentrations of ascorbate and glutathione were found in the chilling-treated plants throughout the different period of growth in comparison with those in the control plants. The activities of superoxide dismutase, ascorbate peroxidase, and glutathione reductase increased in the chilling-treated seedlings while activities of catalase and peroxidase and of β-carotene content decreased in young chilling-treated plants and slightly increased in older ones.

Five wild herb legumes (Trifolium resupinatum, Melilotus indica, Medicago intertexta, Trigonella hamosa, and Alhagi murarum) were collected from cultivated lands of the Nile Valley, and compared with clover (Trifolium alexandrinum), a cultivated forage legume. The wild herb legumes exhibited great variation in nodulation percentage, nodule number, nodule mass and acetylene reduction activity with regard to locality. Nodulation of T. resupinatum and M. indica ranged between 50 - 100% and 33 - 100%, respectively, compared to 50 - 100% for T. alexandrinum. The number of nodules formed on T. resupinatum was 9 - 128 and that of M. indica 6 - 39, compared to 13 - 122 nodule per plant for T. alexandrinum. Nodule mass was correlated with nodule number. In M. indica, a small number of nodules was compensated with high specific nitrogenase activity. The herb legumes formed nodules of small size, varying shape (globose, cylindrical, branched, etc.), and of different types (crotalaroid and astragaloid). Microscopic examination of root-nodules from T. resupinatum, M. indica and M. intertexta, showed that these legumes formed indeterminate and effective nodules, containing apical meristems, central symbiotic tissue with characteristic zonation and peripheral vascular bundles. The nodules harboured bacteroids with pleiomorphic morphology.

In non-acclimated bean plants heat shock induced oxidative damage (increase of free radical concentration and drop of bound thiols, indicating aggregation of proteins) which was regulated by the enhanced activities of peroxidase and superoxide dismutase, as well as by the accumulation of polyphenols and especially of polyamines. In the plants acclimated to high temperature no oxidative damage occurred following heat shock.

The present study pertains to the effect of different concentration of NaCl on the contents of proteins, free amino acids, proline and glycine betaine in leaves, stems and roots of Ipomoea pes-caprae. The protein content of the tissues increased in response to salinity upto 200 mM NaCl; the free amino acids content showed a reversal trend. The proline and glycine betaine contents increased with increasing salinity upto 500 mM NaCl. The accumulation of proline and glycine betaine might play a role in the alleviation of salt stress.

Zilla spinosa plant part extracts exhibited significantly different inhibitory effect on the seed germination and seedling growth of its associate species. Shoot extract reduced the percentage germination and seedling length of different test species more than root extract. Except of Z. coccineum, seedling growth was more sensitive than seed germination. Shoot/root ratio of all test species increased significantly with increase in extract concentration. Mycelia growth of the two rhizosphere fungal species was more significantly reduced by Z. spinosa shoot extract than root extract. The effects of the different extracts on total protein and total carbohydrate contents of the two test species were comparable. Non-significant increase was recorded at low concentration of both shoot and root extract. However, with the rise of extract concentration, highly significant reduction in the content of these metabolites was recorded.

The most basal endosperm cells of maize (Zea mays L.) began differentiating into transfer cells in 10 days after pollination (DAP). The thickening and ingrowths forming in the transfer cell wall were slow during 10 and 15 DAP. There were many vesicles, silky and string ball objects in cytoplasm, and the number of mitochondria and rough endoplasm reticulum increased. After 15 DAP, the wall thickening and ingrowths forming in the transfer cells sped up. By 20 DAP, the transfer cell zone had developed, there appeared 65 - 70 rows of cells in width and 3 - 4 layers of cell in depth, the obvious cell wall ingrowths presented strong positive reaction with periodic acid Schiff's reagent. After 20 DAP, no significant change appeared in the shape and structure of the transfer cells, and the transfer cells entered function stage. In the mature kernels (53 DAP), the most basal transfer cells were filled with ingrowths, however, dense cytoplasm was also found in these cells. The nuclei had quite irregular shapes in these cells. Some transfer cells contained black grains and crystals. A black layer formed in the pericarp tissue adjacent to the transfer cell zone. Full development of endosperm transfer cells was important for reduction of kernel abortion and increase of kernel mass.

The effects of modifying local source-sink relations on fruit and leaf characteristics of young pear trees were evaluated during the 1997 - 1998 growing season. The following treatments were applied: early spur ringing (ESR) from 27 days after full bloom (DAFB), late spur ringing (LSR) from 97 DAFB, early 15 % spur leaf area removal (ELAR) and late 15 % spur leaf area removal (LLAR). ESR and LSR significantly inhibited fruit growth, suggesting that the fruiting spurs were not fully autonomous in their carbon economy. ELAR and LLAR had little effect on fruit size; sink strength was demonstrated here, since the presence of the fruit caused an efficient transfer of photoassimilates. ESR treatment decreased specific leaf mass (SLM) by 23.84 % when measured 94 DAFB. ELAR did not significantly influence SLM. Treatments had no marked influence on fruit quality.

Fourteen days-old bean plants, grown on sand with Knop's nutrient solution were subjected to water stress (three days without irrigation). The stress led to a decrease in almost all lipid classes except phospholipids in the primary leaves. The content of palmitic acid increased, and that of the linolenic acid decreased. An increase of hexadecenoic acid in phospholipids was also observed. Rewatering for 24 h led to the recovery of the stressed plants including that of the photosynthetic apparatus, but the changes in the lipid composition were insignificant. The spraying of the plants before and after the water stress with 5 × 10-6 M solution of the phenylurea cytokinin 4-PU-30 alleviated negative effect of water stress on the lipid membrane composition permitting the plants to resist the harmful environment.

Aim of this work was to find the best source for obtaining high amount of copper amine oxidase (EC 1.4.3.6) that can be further used for analytical or industrial applications. The study focused on plant enzymes, because they occur in much higher content in the starting material than the enzymes from other sources, have higher specific activity and are also more thermostable. Presence of the amine oxidase was tested in extracts from 4 to 7-d-old seedlings of thirty-four various Fabaceae plants. Amine oxidases from nine selected plants were purified by general method involving ammonium sulfate fractionation, controlled heat denaturation, and three chromatographic steps. Kinetic properties of the amine oxidases purified were tested with a wide range of substrates and inhibitors and were found to be very similar. Best purification yield, and total and specific activities were obtained for the enzyme from grass pea (Lathyrus sativus) throughout all purification steps. Hence, the grass pea extract was chosen as a suitable candidate for massive production of the amine oxidase.

Detached wheat shoots (ear with peduncle and flag leaf) were incubated for 4 d in a solution containing 1 mM RbCl and 1 mM SrCl2 as well as 10, 40 or 160 µM NiCl2 and CoCl2. The phloem of some plants was interrupted by steam-girdling the stem below the ear to distinguish between xylem and phloem transport. The phloem-immobile Sr flowed mainly to the leaf lamina and to the glumes via the xylem. The Sr transport was not sensitive to steam-girdling. In contrast, the phloem-mobile Rb accumulated during the incubation time mainly in the stem and the leaf sheath. The Rb transport to the grains was impaired by steam-girdling as well as by elevated Ni and Co concentrations in the incubation solution indicating that Rb was transported via the phloem to the maturing grains and that this transport was affected by the heavy metals. Ni was removed more efficiently from the xylem in the peduncle than Co (but far less efficiently than Rb). It became evident that the two heavy metals can also be transferred from the xylem to the phloem in the stem of wheat and reach the maturing grains via the phloem.

The greatest growth of wheat and rape plants in vitro was reached on media with 5 or 9 % sucrose, respectively. The highest efficiency for transfer of these plants to ex vitro conditions was found at the same sucrose concentrations. The content of endogenous non-structural saccharides (glucose, fructose, sucrose, starch and fructans) increased with increasing sucrose concentration in the medium up to 10 %.

Barley (Hordeum vulgare L., cv. Hemus) plants were grown in nutrient solution with or without 54 µM Cd²⁺ for 12 d. A treatment with Cd²⁺ inhibited the growth of young barley plants. The main factor limiting plant growth was net assimilation rate, due to decreased photosynthetic rate and accelerated dark respiration rate. One of the reasons for the reduced photosynthetic rate was the lower chlorophyll and carotenoid content. Cd²⁺ decreased water potential and transpiration rate, but relative water content in leaves of the treated plants was not significantly changed.

The changes in nuclear ultrastructure during garlic development were investigated. In quiescent cells, the nucleus was oblate and small, full of heterochromatin, and without nucleolus. In the active phase cells, the nucleus moved toward the center of the cell, and was enlarged with many deep fissures, and the heterochromatin in the nucleus turned to be euchromatin. One or more nucleoli were seen in active phase cells. Cell divisions were by means of amitosis. Relatively large nuclei with small distortions were seen in the callus cells. These results suggest that the metabolism of the active cells was higher than that of callus and quiescent cells.

Changes in saccharide contents of tea leaves during infection with blister blight fungus Exobasidium vexans Masse was studied. Saccharose and glucose contents decreased in the blistered portions when compared to the normal regions until sporulation and remained constant during the entire period of sporulation. Fructose content increased abruptly during the initiation of sporulation and remained constant up to the end of sporulation in both blistered and non-blistered regions. Starch content continuously decreased in the blistered region. Peroxidase activity was highly enhanced during the final stages of leaf senescence. The activity of acid invertase was inversely proportional to the starch content and closely related to the changes in the saccharose and glucose contents. Protein and chlorophyll contents gradually decreased in the blistered regions.

A precursor in tetrapyrrole biosynthesis, 5-aminolevulinic acid (ALA), was applied via presowing soaking in Vigna catjung, V. mungo, and V. radiata. ALA increased plant growth and influenced dry matter accumulation in leaves, stems, and pods through increased chlorophyll content and photosynthetic CO₂ absorption. At harvest, ALA treated plants had increased number of pods per plant, seeds per pod, 100 seed dry matter, biological yield, and the harvest index. Therefore, pretreatment of seeds with optimal concentration of ALA is recommended for improving the growth and productivity of tropical legumes.

Biochanin A, luteolin, naringenin and quercetin significantly decreased the percentage of root segments bearing the intraradical proliferating hyphae of Glomus fistulosum at the concentrations up to 10 µmol dm^-3. The growth of hyphae was inhibited by biochanin A and luteolin whereas no significant effects of quercetin and naringenin were observed.

Exposure of coffee to low temperatures caused growth inhibition, changes in metabolic rates, and membrane alterations. Root tissue exposed to 10 °C evolved significantly lower rates of metabolic heat compared with controls grown at 25 °C, and the values were closely associated with the observed root growth inhibition. Electron paramagnetic resonance spectra of intact tissues showed that the spin probe 5-doxylstearic acid was capable to intercalate within the cellular membrane lipids. Indeed, at the depth of the 5th carbon atoms of the alkyl chains, the nitroxide radical detected more rigid membranes in seedlings exposed to 10 °C compared with 25 °C treated samples. Ascorbate peroxidase and catalase activities did not show appreciable changes under chilling conditions, while guaiacol peroxidase activity increased 55 % compared to the control. On the other hand, glutathione reductase activity decreased, in parallel to a significant decline in the capacity to reduce triphenyl-tetrazolium. Our results showed a marked correlation between lipid peroxidation and root tissue damage, which seemed to be associated with increased membrane rigidity.

Direct somatic embryogenesis from shoot apical meristems of pea is described. Somatic embryos were induced directly (without callus intervention) from meristematic tissues grown on a medium supplemented with 2.5 µM picloram. Within 4 to 5 weeks, fully morphologically developed somatic embryos were obtained. Somatic embryos originated from apical as well as from basal parts of meristem explants. The initiation and development of somatic embryos was asynchronous, basal somatic embryos developed more quickly than apical ones. Abundant secondary embryogenesis was observed after isolation of primary somatic embryos and culturing them on media for germination. Morphologically normal somatic embryos germinated on medium without growth regulators; the conversion rate was increased by application of 10 µM thidiazuron (TDZ). TDZ was also able to induce shoot bud regeneration on embryos without differentiated a shoot apex, allowing to germinate up to 78 % of all harvested somatic embryos with various morphology. The protocol was successfully tested in 47 out of 48 P. sativum and P. arvense cultivars as well as in two wild peas (P. elatius, P. jomardi).

The effects of ethylene on postharvest horticultural produce are a major limiting factor in their orderly and efficient marketing. Nitric oxide and nitrous oxide have recently been shown to inhibit ethylene action and synthesis in higher plants and their potential for commercial use to extend the storage and marketing life of fruits, vegetables and flowers is reviewed.