Indoor experiments demonstrated that allelopathic potential of rosette and flowering plants of qort is an important factor explaining the growth reduction of its associated species. Aqueous tissue extracts of flowering plants exhibited strong inhibitory effects on the germination percentage and radicle growth rate of the tested species as compared with those of vegetative plants. Under laboratory conditions, this inhibition was in agreement with toxicity assessments of soil samples collected from the rhizosphere of T. resupinatum L., where shoot and root dry mass of the tested species were significantly reduced. Detoxification of allelochemicals by presence of activated carbon can eliminate the inhibitory effects of the different extracts. This technique clarifies the occurrence of allelopathic interference by qort on seed germination and seedling growth, and hence suspects the allelopathic potential of qort in the growth reduction of associate species under field conditions along with competition.

Gas chromatographic measurements demonstrated that the content of endogenous gibberellic acid increased and that of abscisic acid decreased during storage of potato seeds, suggesting that the dormancy of the seeds is controlled by the balance between these two hormones.

The effect of low irradiance on three rice cultivars (shade tolerant cvs. Swarnaprabha and CO 43 and shade susceptible cv. IR 20) was studied. The large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase/oxygenase with molecular mass of 55 kDa was reduced in cv. IR 20 grown under low irradiance (LI). Native protein profile studied showed, under LI, reduction in the contents of proteins with RF values 0.03, 0.11 and 0.37. Analysis of chloroplast polypeptides revealed an induction of light-harvesting chlorphyll-protein 2 (LHCP2) under shade. The induction was more expressed in cv. CO 43 than in cv. IR 20. Under LI, in vivo labelled protein bands in the molecular range of 26 - 27 kDa were induced. These proteins were highly turned over in the LI-grown plants of cv. CO 43 than in cv. IR 20. A signal for rbcL gene sequences in EcoRI digested lanes was also found. Isozyme analysis of peroxidase showed an induction of a new band with RF 0.43 in cv. IR 20 subjected to LI.

The effects of Cd, Ni and Pb on the growth, chlorophyll (Chl) and protein contents, and content of proteases of potted weed plants Cyperus difformis, Chenopodium ambrosioides and Digitaria sanguinolis were determined. The three heavy metals inhibited the shoot growth but were less suppresive to root growth. They also lowered leaf Chl content. The changes in root and shoot protein and proteases contents of weeds were interrelated. The heavy metal additions to soil increased their contents in both roots and shoots, several times more in roots than in shoots.

The distribution of the stress-related anionic peroxidase in the course of cucumber (Cucumis sativus L.) seed germination was determined by tissue printing and immunoblotting. Of the three molecular forms of cucumber stress-related anionic peroxidase, the form PRX 1 was temporally accumulated in developing seedlings. Up to 6 d of germination PRX 1 was localized mainly in roots. As germination progressed, the immunoreactive PRX 1 signal was found in the transition zone between roots and stem, as well as in the lower epidermis of expanding cotyledons at the midrib.

Random amplified polymorphic DNAs (RAPD) analysis has been adapted to assess the degree of RAPD polymorphism within the genus Hordeum to determine if this approach can distinguish wild and cultivated species. Nineteen wild and seven cultivated accessions were evaluated using 4 random 10-mer primers. The potential of the RAPD assay was further increased by combining two primers in a single polymerase chain reaction (PCR). RAPD fragments generated by two pairs of arbitrary 10-mer primers discriminated six wild species and one cultivated species by banding profiles. The size of the amplified DNA fragments ranged from 150 to 2300 base pairs. 33 %percent of the fragments were common to both wild and cultivated species; 67% were specific to either wild or cultivated species. The average difference in fragments was less within the species than among the species. By comparing RAPD fingerprints of wild and cultivated barley, markers were identified among the set of amplified DNA fragments which could be used to distinguish wild and cultivated Hordeum species.

We used chlorotetracycline fluorescence, alizarin staining and potassium pyroantimonate methods, as well as X-ray microanalysis, to demonstrate the differential localization of Ca2+ during pollen maturation. Level of loosely-bound Ca2+ ions was higher in the generative cell than in the vegetative cell of the mature pollen grain which is one of the symptoms of metabolic differentiation of the two sister cells.

Culture conditions for a fine dispersion of plated cells of Oryza sativa L. cv. IR 20, have been worked out. These plated cells developed microcalli containing large number of somatic embryos and subsequently plantlets. By using single cells and clusters of 2 - 4 cells, an efficient DNA-delivery by microprojectile bombardment into cells and its transient expression were assessed by employing a plasmid construct containing β-glucuronidase gene.

A concentration dependent decrease in root nitrate reductase (E.C.1.6.6.1) activity (NRA) by 0.1 to 2.0 mM lead acetate was noticed in three cultivars of Vigna radiata (L.) Wilczek (K851, MH8320 and ML337). Leaf NRA, on the other hand, increased significantly with increasing lead concentration which was more pronounced in cvs. MH8320 and ML337 than in cv. K851. Total nitrogen content of root and shoot was generally increased due to supply of the lead acetate, whereas the total nitrogen content of the colyledons was hardly affected in cvs. MH8320 and ML337 and decreased in cv. K851 during the early growth phase. The inhibition of root NRA could be alleviated by addition of inorganic salts (K2HPO4 and KNO3, but not CaCl2) or 6-benzylaminopurine (BAP) in the incubation medium. Lead mediated inhibition of root NRA was similar in light and dark grown seedlings, but lead induced increase in leaf NRA was more pronounced in the light than in the dark.

Media from embryogenic and non-embryogenic cell suspension cultures were analysed for protein content, electrophoretic protein patterns, glycoproteins and activity of peroxidases and β-glucosidases in order to characterize the physiological status of the cultures. On a dry mass basis the amount of extracellular proteins per cell was greater in embryogenic suspensions than in non-embryogenic suspensions. Non-embryogenic suspensions contained unidentified slimy compounds which were not present inembryogenic cultures. The extracellular Concanavalin A-specific glycoproteins gave different isoelectric focussing patterns and thus enabled embryogenic and non-embryogenic cultures to be differentiated. The extracellular peroxidase activity per cell dry mass was far greater in embryogenic than in non-embryogenic cultures. The isoenzymes differed in number and composition of the anionic bands. β-glucosidases were found in the same range of activity in both culture types, but the time course of enzyme activity during cultivation was significantly different. In the embryogenic culture the activity was correlated with dry mass increase, whereas in the non-embryogenic suspension the activity reached maximum during the linear growth phase. Polyphenoloxidase which was recently recognized as an intracellular marker for embryogenic stages was not released into culture media.

The ontogenetic changes in source-sink relation associated with the manipulation of reproductive sink at different positions on the plant in two okra cultivars (Arka Anamika and Pusa Makhamali) with distinct branching habit (cv. Arka Anamika tends to branch at the middle nodes unlike cv. Pusa Makhamali) were analysed. The cultivar differences for extension growth were nonsignificant except at treatment where all flowers and flower buds upto 8th mode were removed. The reproductive sink reductions resulted in a decrease of total dry matter accumulation per plant to an extent of 13 to 46% in Arka Anamika and 18 to 34 % in Pusa Makhamali. Fruits on the middle nodes appear to be prominent sinks for photo assimilates in cv. Arka Anamika. The reproductive sink manipulation did not result in any particular change in the trend of photosynthesis, but brought about a significant change in the partitioning of dry matter.

Shoot regenerations from hypocotyls and cotyledons of tomato(Lycopersicon esculentum Mill.) was inhibited by NaCl (100 and 150 mM).Shoot fresh and dry masses were also reduced. Addition of proline (100 mgdm-3) counteracted the inhibitory effect of NaCl. SDS-PAGE analyses of extracted proteins, revealed that in cultures grown in medium with 25 mM NaCl plus proline, extra polypeptides of Mr 190, 58, 45 and 26 kDa accumulated. As NaCl was increased in the medium a new protein of Mr 67 kDa also accumulated.

Source-sink relationship, which was influenced by both genotype and environmental factors, contributed to the variation in photosynthesis and photosynthate partitioning of wheat. Source reduction by partial defoliation increased leaf net photosynthetic rate (PN), and sink reduction decreased PN of irrigated wheat. However, the change in PN varied among genotypes. Source reduction enhanced photosynthate translocation into grain in irrigated wheat. However, the enhancement was more evident in cv. Lumai 215953 than incv. Lumai 15. Sink reduction had little effect on the translocation of photosynthate into grain in cv. Lumai 15, but decreased the translocation of photosynthate into grain and increased it into stem in cv. Lumai 215953. In rainfed, non-irrigated wheat, the source or sink manipulation influenced PN only slightly. The source reduction decreased the partitioning of photosynthates into the upper parts (including grains) of plant. However, very little effects of sink reduction on the production of photosynthates occurred in rainfed wheat. This showed that grain sink size was not a factor limiting the production of photosynthates, but controlled the partitioning of photosynthates. Sink reduction decreased photosynthate translocation into grains, and increased it into upper parts of rainfed wheat plant.

Friable calli were induced from mature excised shoots of Bambusa vulgaris on Murashige and Skoog's (MS) medium supplemented with 2.2 µM6-benzylamino-purine (BAP), 9.04 µM 2,4-dichlorophenoxyacetic acid and 14.76 µM indole-3-butyric acid (IBA) with 3 % (m/v) saccharose. Adventitious shoots with root hairs were achieved from calli on MS medium supplemented with 13.33 µM BAP and 1.23 - 2.46 µM IBA within 4 weeks of subculture. The frequency of shoot bud regeneration was better in the light incubated cultures than in the dark incubated cultures. Isolated shoots were rooted on liquid half-strength MS basal medium supplemented with 0.49 µM IBA and 2 % (m/v) saccharose. Histological observations confirmed the regeneration of shoot buds from calli. The rooted plantlets were successfully transferred to greenhouse.

A method for DNA extraction from Pyrrosia piloselloides (L.) Price and Pyrrosia longifolia (Burm.) Morton utilising hexadecyltrimethylammonium bromide is described. The genomic DNA isolated was found to be relatively pure and shown to be suitable for RAPD analysis.

The effect of five Azotobacter chroococcum strains and nitrogen content in nutrient media on callus growth of two Beta vulgaris L. cultivars were investigated, as well as the activity of nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in inoculated callus tissue. On medium with full nitrogen content (1 N) the inoculation with A. chroococcum strain A2 resulted in the highest calli mass, while strains A8 and A14 maximally increased NR activity. On media with 1/8 N the highest effect on calli growth, GS and GDH activity had the strain A8. The strain A2/1 significantly increased callus proliferation on medium without N. Asymbiotic association between sugar beet calli and Azotobacter depended on genotype/strain interaction and was realised in presence of different nitrogen levels.