Romanian Journal of Biology - Plant Biology
Volume 56, No. 2, 2011
1. ANALYSIS OF THE CHARACTERS ON SOME ANGELICA TAXA
pp. 79 - 89
G. DIHORU, MIHAELA PAUCĂ-COMĂNESCU, ROXANA ION
Angelica archangelica was at times confused with A. sylvestris subsp. montana, especially for size, vesicular vaginas and spherical umbels. The essential difference between them is reflected by the fruit not attached to the seed, whitish, with numerous thin secretory channels, not visible from the outside at A. archangelica and connate to the seed, brown, with six large secretory channels, externally visible as black stripes on the montana subspecies.
2. INDUCTION OF QUANTITATIVE VARIABILITY THROUGH EMS TREATMENT IN VIGNA UNGUICULATA
pp. 91 - 97
G. KUMAR, SHWETA VERMA
The present study was conducted to evaluate the effect of EMS on different morphological yield parameters of cowpea in M1 and M2 generations. Both positive and negative shifts in mean values of yield parameters were recorded as a result of EMS treatment. Cowpea being a self-pollinated vegetable crop has very limited genetic variability therefore induced mutation can provide an additional source of mutation in a recent plant breeding programme. Hence, an experiment was conducted to evaluate the extent genetic variability in morphological quantitative characters in M1 and M2 generation following mutagenesis with EMS. By inducing mutation in cowpea, it may be possible to identify new beneficial traits for higher yield. Thus aim of the present study is to identify and select mutants with useful morphological attributes.
3. INHIBITION OF STEROL BIOSYNTHESIS IN TOMATO PLANT RESULTING IN ANTIVERMIN PROTECTION
pp. 99 - 107
Plant sterols are important ingredients of the plant’s cell membrane or composition, regulate the fluidity and permeability and modulate the activity of bond enzymes required for growth and development. In vitro, using the methods of cell selection to study the effect of morpholines fungicide fenpropimorph on tomato plant (Lycopersicum esculentum var. pritchard), numbers of differentiated and undifferentiated tissues were affected. A few number of organogenic calluses and primary calluses were observed growing at the lethal concentration (50 mg L-1). Organogenic calluses were more sensitive to the effect of fenpropimorph than primary ones. Higher decrease in the dry weight values and sterol contents was observed in fenpropimorph growing calluses, Seed germinated and regenerant fenpropimorph (20 mg/L-1) treated plants showed a higher decrease in the sterol contents compared with control ones. Fenpropimorph regenerant plants showed a higher decrease in the sterol contents than its seed germinated ones. Fenpropimorph (40 mg/L-1) treated calluses were examined as exogenous supply of sterol in the diet of D. melanogaster; they decreased the number of progenies.
4. INHIBITION OF STEROL BIOSYNTHESIS IN TOMATO PLANT RESULTING IN LOW DOSE OF GAMMA IRRADIATION ENHANCED DROUGHT TOLERANCE IN SOYBEAN
pp. 109 - 121
Drought stress is the main limiting factor of soybean production. However, no work has been done on how application of low-dose of gamma rays could help to overcome water deficits during critical stages of soybean development. Gamma rays at doses 0.0 and 20 Gray (Gy), from a cobalt source (60Co) with strength of 500 Ci and the dose rate of 0.54 Gy/min-1, were applied to dry seeds of soybean before planting. Two levels of soil moisture (80% field capacity for well-watered control and 35% for droughtstressed treatment) were applied at pod initiation. Thereafter, the interaction effects of low dose of gamma irradiation and water stress on some growth, biochemical, anatomical and antioxidative parameters of soybean plants were investigated. Low dose of gamma irradiation increased biomass accumulation and seed yield for both treatments. Drought stress depressed chlorophyll content and photosynthetic activity (14CO2-fixation), while chlorophyll content, leaf water potential and photosynthetic activity of plants irradiated with gamma rays at a dose 20 Gy were greater than that of drought-stressed plants. Water deficit decreased the enzyme activities of phosphoenol pyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase/oxygenase. However, application of low dose of gamma irradiation (20 Gy) increased the activities of these enzymes, except for phosphoenol pyruvate carboxylase under drought stress. Gamma irradiation dose at 20 Gy increased the concentration of soluble sugars, protein and proline content and the activities of peroxidase and superoxide dismutase of soybean leaves when drought-stressed. However, it decreased the malondialdehyde concentration and electrical conductivity of leaves under drought stress. The following physicochemical characteristics of chloroplasts were chosen as indicators of droughtstressed effects: average size, and ultrastructure. The results suggest that gamma irradiation at dose 20 Gy can partly counterbalance the destructive effects of water deficits. This protective action led to an increase of chloroplast size reduced by drought treatment and rebuilt, to some extent, the chloroplast ultrastructure. Overall, the results indicated that pre-treatment with low dose of gamma rays (20 Gy) to dry seeds of soybean before planting can be used to enhance drought tolerance and minimize the yield loss caused by water deficits. Thus, it may be a useful management tool in afforestation projects in arid and semiarid areas as a promising technique for agricultural improvement.
5. IN VITRO PREVENTION OF BROWNING IN PLANTAIN CULTURE
pp. 123 - 130
C.I. ONUOHA, C.J. EZE, C.I.N. UNAMBA, C.K. UGOCHUKWU
The in vitro propagation of plantain (Musa paradisiaca) is still faced with lots of challenges such as blackening or browning of tissues prior to culture due to the oxidation of phenolic compounds by the polyphenolic oxidase enzyme present in the tissue when excised. Understanding browning processes in plantain and possible ways of minimizing it during excision of explants with particular emphasis on the use of antioxidants was the purpose of this work. Tissues were surfaced sterilized with 0.1% (w/v) HgCl2 for 1-6 mins to get a pure culture and then treated for two hours with different concentrations of 0.1, 0.2, 0.3, 0.4 and 0.5 mg/ml of potassium citrate and citrate (K-C:C) as an antioxidant to check browning while sterile distilled water was used as control. The result showed that contamination free culture (100%) was achieved in the explants treated with HgCl2 for 6 mins. Also the various concentration of K-C:C prevented browning within 2 hours before culturing the tissues thus inferring that browning in young plantain excised tissue can be greatly reduced by presoaking or pretreatment with antioxidant solution of potassium citrate-citrate before culturing them.
6. A STUDY OF PATHOGENIC FUNGI ASSOCIATED WITH CITRUS DECLINE AT THE ORCHARDS OF NIGERIA INSTITUTE OF HORTICULTURAL RESEARCH (NIHORT)
pp. 131 - 139
I.O. EZEIBEKWE, A.U. OFONG, N. ONYIKE
Disease surveys were conducted at the Cirus orchards of National Horticultural Research (NIHORT), Mbato, Okigwe to ascertain pathogenic fungi associated with citrus decline. Isolations showed that Phytophthora palmivora (Butler), Botryodiplodia theobromae (Pat), Fusarium oxysporum (Schlechtend), and Fusarium equiseti (Wollen) were constantly isolated from the rhizosphere (soil) roots, stem and leaves. Pathogenicity studies confirmed these microorganisms as responsible for some of the diseases especially Citrus decline.
7. COMPLEMENTARY EFFECTS OF Glomus fasciculatum AND PHOSPHATE SOLUBILIZING MICROORGANISMS ALONG WITH Rhizobium leguminosarum ON BLACK GRAM (Vigna mungo L.)
pp. 141 - 152
K. SIVAKUMAR, P. THOLKAPPIAN
Experiments were conducted to evaluate the effects of nitrogen fixing Rhizobium leguminosarum, phosphate solubilizing bacterium (Bacillus subtilis), phosphate solubilizing fungus (Aspergillus awamori) and AM fungus (Glomus fasciculatum) on growth, chlorophyll content, seed yield, nodulation, grain protein, and N and P uptake of black gram growing in phosphorus-deficient soils. The triple inoculation of AM fungus, Rhizobium leguminosarum and B. subtilis significantly increased dry matter yield, chlorophyll content in foliage and N and P uptake of black gram plants. Seed yield was enhanced by 24% following triple inoculation of R. leguminosarum + G. fasciculatum + B. subtilis, when compared to that of control. Nodule occupancy, determined by indirect enzyme linked immunosorbent assay (ELISA), ranged between 77% (R. leguminosarum + A. awamori) and 96% (R. leguminosarum + G. fasciculatum + B. subtilis) at flowering (45 DAS), decreasing at the pod-fill (60 DAS) stage by each treatment. Replica immunoblot assay (RIBA) revealed a greater variation in the rhizobial populations within nodules. The correlation between nodule occupancy and immunoblot counts was highly significant at 45 (r = 0.95) and at 60 DAS (r = 0.96). There was a negative effect on some of the measured parameters when A. awamori was used alone or added to the combination treatments. The present findings showed that rhizospheric microorganisms can interact positively in promoting plant growth, as well as N and P uptake of black gram finally leading to improved yield.
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