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Appropriate Nutrient Economy in Phragmites australis at Different Phases of Estuarine Succession
Issue:
Volume 2, Issue 4, August 2014
Pages:
120-128
Received:
2 July 2014
Accepted:
17 July 2014
Published:
30 July 2014
Abstract: The common reed Phragmites australis (Cav.) Trin ex Steudel – the dominant macrophytic plant species in the Kokemäenjoki River delta, western Finland – showed distinct and appropriate trends in the nutrient economy according to the previously determined successional phases of the vegetation development. The height and weight of individual aboveground shoots (ramets) decreased in the order: Pioneer stage > Mature stage > Regressing stage. The concentrations of the major nutrients nitrogen and phosphorus were determined only partly by amounts of these nutrients in the plants’ rhizospheres. The estuary is eutrophic, and the river water guarantees a continuous supply of nutrients, and thus the levels of nitrogen and phosphorus are high throughout the study area. The levels of nutrients correlated significantly with the contents of organic matter in the rhizospheres of the reed stands. On the basis of the relationships between the major nutrients’ concentrations in the leaf blades, nitrogen appeared to be the growth-limiting nutrients in the pioneer stage of succession in these estuarine habitats. The N/P-ratios in the three stages were as follows: Pioneer stage: 10.75, Mature stage: 13.59, Regressing stage: 14.67. In general, the values below 15 are considered to be nitrogen-limited. The actual levels of N and P in the leaf tissues were, however, high throughout the study. As evaluated by the concept of critical concentration, i.e. the level of a nutrient, which guarantees maximal growth potential, the habitats at all the three successional phases showed adequate level of nutrient availability for the maximal production of Phragmites. At the pioneer stage, where the rhizosphere resources of nutrients were poorest, the common reed showed an appropriate morphological adaptation. In the pioneering stands, the common reed produces considerable amounts of adventitious roots (water roots) on the underwater sections of the culms. In the pioneer stage, the average weight of the water roots was 675 mg/ramet in the fertile (flowering) shoots and 267 mg/ramet in the sterile (non-flowering) shoots, i.e. 2.6–5% of the total weight of the aboveground shoots. In the mature stage, the amount of adventitious roots was minor, but in the regressing stage – where growth enhancement and substantial flowering is essential for the future of the species – the reeds produced more adventitious roots again.
Abstract: The common reed Phragmites australis (Cav.) Trin ex Steudel – the dominant macrophytic plant species in the Kokemäenjoki River delta, western Finland – showed distinct and appropriate trends in the nutrient economy according to the previously determined successional phases of the vegetation development. The height and weight of individual abovegrou...
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Evaluation of Sorghum (Sorghum bicolor (L.) Moench) Varieties, for Yield and Yield Components at Kako, Southern Ethiopia
Tekle Yoseph,
Zemach Sorsa
Issue:
Volume 2, Issue 4, August 2014
Pages:
129-133
Received:
29 July 2014
Accepted:
15 August 2014
Published:
30 August 2014
Abstract: A field experiment involving seven improved sorghum [Sorghum bicolor (L.) Moench] varieties and one local check was carried out at Kako farmers’ training center during the 2006 main cropping season to identify the best performing variety to the lowlands of South Omo Zone. The sorghum varieties included in the field experiment were seven improved (Seredo, Meko-1, 76TI#23, Gambella 1107, Teshale, Gubiye, Abshir) and a local check. The experimental design was a randomized complete block design (RCBD) with three replications. Phenological and growth parameters such as yield and yield components, total biomass and harvest index were studied. The result showed that all phenological and growth parameters were significantly affected by variety except number of tillers and panicle length per plant. There was a proportional increment on the number of tillers per plant observed for the improved sorghum varieties over the local check. Grain yield, total biomass, 1000 seeds weight and harvest index were significantly affected by variety. Grain yield advantages of 74.26%, 64.96% and 58.06%, were obtained from the improved sorghum varieties Teshale, Meko-1 and Gambella 1107, respectively over the local check. The highest grain yields of (3.3667 t ha-1) and (2.4733 t ha-1) were recorded for the varieties Teshale and Meko-1, respectively. Therefore, it can be concluded that use of the improved sorghum varieties such as Teshale or Meko-1 is advisable and could be appropriate for sorghum production in the test area even though further testing is required to put the recommendation on a strong basis.
Abstract: A field experiment involving seven improved sorghum [Sorghum bicolor (L.) Moench] varieties and one local check was carried out at Kako farmers’ training center during the 2006 main cropping season to identify the best performing variety to the lowlands of South Omo Zone. The sorghum varieties included in the field experiment were seven improved (S...
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Leghaemoglobin Sub-Fractional Components in Chickpea Root Nodules during Extended Darkness
Issue:
Volume 2, Issue 4, August 2014
Pages:
134-138
Received:
6 August 2014
Accepted:
13 August 2014
Published:
30 August 2014
Abstract: The aim of study was to investigate qualitative behavior of leghaemoglobin sub-fractional components during dark induced nodular senescence. A conventional protein purification method using ion exchange chromatography (HPLC) readily resolved ferric Lb into eight sub-fractional components namely a1, a2; b; c1, c2 and d1, d2 d3 in the unstressed chickpea nodules. Lb complexes behave differently during growth phases of the nodules. Lb ‘a’ complex is directly related to the growth and developmental of nodules wherein proportion of Lb a2 content increases with age of nodule accompanying concurrent decrease Lb a1. Early appearance of senescence related isoprotein Lb a2 at vegetative phase of chickpea cultivar correlates its stress-susceptible nature. Further, the turnover rates of Lb a1 to a2 and Lb b were insensitive to reduced supply of photosynthesis during dark stress and even re-illumination. The relative proportion of c2 to c1 inversion increases during darkness. Further, Lb‘d’ complex is affected the most during prolonged darkness. Thus, ratio between individual sub-fractional components of Lbs’ can be correlated with the development phase, longevity and supply of carbohydrates to nodules.
Abstract: The aim of study was to investigate qualitative behavior of leghaemoglobin sub-fractional components during dark induced nodular senescence. A conventional protein purification method using ion exchange chromatography (HPLC) readily resolved ferric Lb into eight sub-fractional components namely a1, a2; b; c1, c2 and d1, d2 d3 in the unstressed chic...
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Effect of Carbon Monoxide Fumigation on the Respiration and Oxidase Activities of Postharvest Jujube
Li Qin,
Zhang Shaoying,
Ju Lili
Issue:
Volume 2, Issue 4, August 2014
Pages:
139-144
Received:
17 August 2014
Accepted:
25 August 2014
Published:
10 September 2014
Abstract: Postharvest jujubes were fumigated with 5, 10, 20 or 40 μmol/L carbon monoxide (CO) for 1 h and then preserved for 30 d at ambient temperature. The effects of CO fumigation on the respiration and oxidase activities of postharvest jujube were determined. Results showed that low CO concentrations (5–10 μmol/L) could restrain the increases of respiration rate, malonaldehyde content, and relative membrane permeability of postharvest jujube. However, high CO concentrations (20–40 μmol/L) showed adverse effects on jujube preservation. Jujube fumigated with 10 μmol/L CO demonstrated optimum effects, and this CO concentration effectively reduced the oxidase activities including lipoxygenase, cytochrome oxidase, polyphenol oxidase and ascorbic oxidase during jujube storage time. As for the reduction of respiration rate and oxidase activities, the delay of membrane lipid peroxidation, fumigating jujube with appropriate concentration of CO might be applied to preserve postharvest jujube and other fruits.
Abstract: Postharvest jujubes were fumigated with 5, 10, 20 or 40 μmol/L carbon monoxide (CO) for 1 h and then preserved for 30 d at ambient temperature. The effects of CO fumigation on the respiration and oxidase activities of postharvest jujube were determined. Results showed that low CO concentrations (5–10 μmol/L) could restrain the increases of respirat...
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