Plant gene technology: social considerations

The genetic modification of plants by gene technology is of immense potential benefits, but there may be possible risks. The advantages and social concerns of plant gene technology are discussed. Key Words: Gene technology, genetically modified plant, agriculture. African Journal of Biotechnology Vol.3(3) 2004: 156-15

The role of seed priming in improving seed germination and seedling growth of maize (Zea mays L.) under salt stress at laboratory conditions

Salinity is considered as a major abiotic stress affecting germination, seedling growth and crop production in arid and semi-arid regions. Many techniques are used to improve tolerance to salinity. Priming is believed to be an effective technique that increases germination, plant growth and improve yield of several vegetables and crops under saline soil condition. The objective of this study was to see the effect of seed priming with 5 g/L NaCl on germination and seedling growth of maize (<i>Zea mays</i> L.) exposed to five salinity levels under laboratory conditions. Maize seeds were soaked in solutions of NaCl (5 g/L) for 12 h at room temperature. Primed and unprimed seeds were sown in Petri dishes and were irrigated with saline solutions of five concentrations (0, 2, 4, 6 and 8 g/l NaCl). Priming seeds with NaCl significantly improved (P<0.05) germination and growth of maize. As a result, fresh and dry weights of shoot and root were improved. Seed priming alleviated the inhibitory effect of salt stress on germination and seedling growth of maize under salt stress. Thus, seed priming with 5 g/l NaCl could be used to improve germination and early growth. Further, this study needs to be continued if performance of mature maize plants could also be improved and yield increased by sowing primed seeds in saline soils.Key words: Maize, salinity, seed germination, seed priming, seedling growth

Efficacy of cactus pear (Opuntia ficus-indica) varieties as a source of food and feed in Endamehoni district, Northern Ethiopia

Cactus Pear (Opuntia ficus-indica) serves as a source of food, feed, as well as a means of additional income to the people in northern Ethiopia. The species has different varieties with varied rate of productivity and palatability. This study was conducted to assess the food and feed value of the Cactus Pear varieties in Endamehoni District, northern Ethiopia. It was carried out in three “Tabias” (small administrative sub-districts) and nine sub-Tabias (also known as “Kushets”). These areas were purposively selected as they are well known for their good diversity of Cactus varieties. A total of one hundred and twenty households (n = 120) were randomly selected for interviews using a semi-structured interview. This was supplemented by information obtained through key informants’ interviews and field visits. The local farmers made the identification and characterization of cactus varieties traditionally based on the outstanding phenotypes like fruit characteristics, seed size and content, cladode descriptors and plant height. A total of 13 Cactus varieties were identified and recorded. To assess the food and feed value and to select the best used varieties in the area, preference rankings were made. It was found that not all varieties were equally edible and palatable. The most serious constraints in palatability were associated with fruit taste, fruit size, presence of spines, and hardness of seeds. The ethnobotanical study on palatability was supplemented by chemical analysis on Dry Matter (DM), Ash, Organic Matter (OM) and Crude Protein (CP) content from two-year-old young cladodes of four Cactus varieties (Kille, Wadwada, Magalla and Limo) that are more preferred for food and feed. The analysis of variance (ANOVA) showed significant differences in DM, OM and Ash content at p<0.05 (not at p<0.10). There was no variation in crude protein content amongst the varieties tested. From the results, it is concluded that propagation and use of varieties Kille, Limo, Magalla and Wadwada by farmers of the area is advisable.Keywords: Characterization, Cladode, Community, ethnobotany, fruit, palatability, preference, propagation, traditional knowledg

Temporal and spatial phytoplankton biomass dynamics in southern Gulf of Lake Tana, Northwestern Ethiopia

Southern Gulf of Lake Tana is southern part of Lake Tana in Northwestern Ethiopia. Water samples were obtained from eight sites of the gulf for six months during November to April 2010/11 twice a month to determine temporal and spatial variation in phytoplankton biomass of the gulf. Phytoplankton biomass data was estimated following total chlorophyll-a concentrations determination methods. There was no significant difference in sampling sites and interactions between sampling sites and months (P>0.05). However, there is a significant difference in sampling months (P<0.05). The absence of significant difference in sampling sites and the interactions might be due to the similarity in human or natural impacts, and phytoplankton growth and decline. But, the presence of significant difference among sampling months might be due to the difference in growth/decline periods of the phytoplankton. Southern Gulf of Lake Tana subparts are similarly impacted naturally or by humans who passed their time around the gulf. The Ethiopian government and concerned non-governmental organizations in general and local communities, in particular, have better cooperate their efforts for conservation and sustainable use of the gulf. Similarly, they have to play in awareness creation for stakeholders to reduce natural/human impacts to the lake gulf

Anatomical variations and distributions of obturator nerve on Ethiopian cadavers

Variations in anatomy of the obturator nerve are important to surgeons and anesthesiologists performing surgical procedures in the pelvic cavity, medial thigh and groin regions. They are also helpful for radiologists who interpret computerized imaging and anesthesiologists who perform local anesthesia. This study aimed to describe the anatomical variations and distribution of obturator nerve. The cadavers were examined bilaterally for origin to its final distribution and the variations and normal features of obturator nerve. Sixty-seven limbs sides (34 right and 33 left sides) were studied for variation in origin and distribution of obturator nerve. From which 88.1% arises from L2, L3 and L4 and; 11.9% from L3 and L4 spinal nerves. In 23.9%, 44.8% and 31.3% of specimens the bifurcation levels of obturator nerve were determined to be intrapelvic, within the obturator canal and extrapelvic, respectively. The anterior branch subdivided into two, three and four subdivisions in 9%, 65.7% and 25.4% of the specimens, respectively, while the posterior branch provided two subdivisions in 65.7% and three subdivisions in 34.3% of the specimens. Hip articular branch arose from common obturator nerve in 67.2% to provide sensory innervation to the hip joint. Accessory obturator nerve was not observed at all in this study. Key words: Variations, obturator nerv

Metabolism of [14C]GA19 and [14C]GA53 by ecotypes of Betula pendula: the role of photoperiod

In many temperate woody species, short days (SDs) induced growth cessation has been shown to be prevented by the application of gibberellins (GAs). Evidence has also been forwarded for the influence of photoperiod on the metabolism of applied GAs. Continuing with this line of research, we studied the metabolism of 14C-labelled GA19 and GA53. [14C]GA19 and [14C] A53 were applied to the apices of the northern ecotype (67º N) and to the leaves of the southern ecotype (64º N) of Betula pendula Roth. under different photoperiods and at different times in order to compare metabolism during day and night periods. Assay of metabolites was made 10 h after application. Less than half of each applied GA was taken in by the plants and most of the activity was recovered from the application points. There was no clear effect of photoperiod on uptake of the GAs. After the HPLC analysis, most of the absorbed radiolabelled GAs were eluted as unmetabolised forms. However, significant levels of gibberellins A20, A29, A1, and A8 were recovered as metabolites of [14C]GA19 both in apical stems and leaves. In 1SD and 4SD-treated plants, there was less metabolism of [14C]GA19 compared to LD-treated plants. The difference was due to reduced metabolism of 14C]GA19 by SD-treated plants during the night period. On the other hand, metabolism of [14C]GA53 was very limited in all day-length treatments and during both, day and night periods. The most abundant metabolite was [14C]GA19 (10% of the activity in the samples). Key words/phrases: Conjugation, ecotype, gibberellins, metabolism, radioactivity SINET: Ethiopian Journal of Science Vol. 28 (1) 2005: 33–4

Effect of Salt Stresses on Seed Germination and Early Seedling Growth of Camelina sativa L.

Camelina sativa is a promising low-input, high yielding biodiesel crop that can be suitable to grow on marginal lands and is a good source of omega-3 fatty acids. But, saltiness is an overall issue of agriculture that constrains the germination, development and productivity of plant because of osmotic and ionic poisonous quality impacts. The aim of this study was to assess the effect of salinity (NaCl and KCl) on germination and early seedling growth of Camelina sativa. Camelina sativa seeds were obtained from agricultural research sector of Wachemo University. In the laboratory, six salinity levels of NaCl and KCl (0, 1, 2, 3, 4 and 5 g/L) were prepared and arranged in completely randomized design with four replications. The result of the study revealed that C. sativa seedlings were differ significantly (p<0.05) on speed of germination, germination percentage, germination index, shoot length, root length, vigor index, root shoot ratio and seedling fresh weight, relative injury rates  of NaCl and KCl, shoot height reduction and root height reduction. However, there is no significant effect between salt type versus salinity level and salt type in all parameters tested except shoot length and shoot height reduction at 5% significant level. The increase in both salts (NaCl and KCl) concentration in culture medium causes a significant decreases in speed of germination, germination percentage, germination index, shoot length, root length, vigor index, root shoot ratio and seedling fresh weight of the salt treated C. sativa seeds as compared with the control (C. sativa seeds watered with distilled water). Similarly, relative injury rates NaCl and KCl shoot height reduction, root height reduction were highly increased as salinity level increases. Generally, as the concentration of NaCl and KCl was increased the overall germination and early seedling performance of C. sativa decreased. The effect of salinity on physiology, molecular and biochemical of properties of C. sativa should be studied. Keywords: Camelina sativa, Salinity effect, NaCl, KCl, Seed germination, Seedling growth

Sesame harvest loss caused by sesame seed bug, Elasmolomus sordidus F. at Kafta-Humera sesame fields

Sesame is an important cash crop in Ethiopia. In Humera, farmers are largely dependent on this important cash crop for their living. The production rate is, however, lower than the national average. There could be many factors for its reduced productivity, but pests especially sesame seed bug is one of the reasons. In this study, sesame seed weight loss due to sesame seed bug was determined at field and laboratory conditions. At both conditions, there was significant seed weight loss when the packaging materials were unlined jute and unlined polythene bags, although the loss at field conditions was severe. In both setups, there was small seed weight loss when the packaging materials were lined. This could be due to moisture loss from the seeds because the bugs could not penetrate the lined bags. From these, farmers are advised to use lined bags for storage and transport the harvested seeds to their stores as soon as possible

Nano Fe3O4–graphite paste modified electrochemical sensor for phosphatic pesticide -chlorpyrifos

A sensitive, cost effective and selective electrochemical sensor has been developed by exploiting iron oxide nano-particles as modifier in the paste of graphite powder. Cyclic voltammetric (CV) and differential pulse voltammetric (DPV) working parameters have been standardized and used practically for the determination of chlorpyrifos (O, O-diethyl O-3, 5, 6-trichloropyridin-2-yl phosphorothioate) pesticide from its aqueous solutions. Both techniques were deployed to investigate the electro-chemical interactions between chlorpyrifos and modified carbon paste sensor along with the redox characteristics at analyte/ sensor interface. The significant enhancement in peak current signals and the improved magnitude of the redox peak potential indicated the awe-inspiring facilitation of the electron transfer process by the modifier at the sensor/ analyte interface. The difference in the redox -potential (ΔEp) and peak current ratio (Ipc/Ipa) have revealed a notable surface enhancement characteristic of the modifier that responds the higher concentration gradient of pesticide at the interface. In lower analyte’s concentration range i.e. from 1.0 to 100μM, the peak current varies directly to the pesticide concentration with detection limit of 2.8 x10-6 mol/L. The relative stability of the modified sensor is fine and the reproducibility of the results is up to 98%, even after a gap of two months. The proposed analytical method is quite successful when applied for the quantification of chlorpyrifos from its aqueous samples. The electrochemical sensing/ detection of the pesticide chlorpyrifos is confirmed by its two electrons redox behavior and the same have been explained by suitable reaction scheme as:Keywords: Nano-iron oxide, Chlorpyrifos, Modified graphite paste, Voltammetry, Electrochemical metho

Application of the AquaCrop model to simulate the biomass of Miscanthus x giganteus under different nutrient supply conditions

There are conflicting opinions about the need to fertilize Miscanthus and, also, the question has been raised whether Miscanthus should be irrigated, especially if water resources are limited. Crop growth modeling can help answer such questions. In this article the FAO AquaCrop water-driven model was selected to simulate Miscanthus biomass under different nutrient and water supply conditions. The article reports the outcomes of 6-year experiments with Miscanthus on two locations in Serbia: Zemun, where three fertilizer treatments were applied (N-l - 100kgha(-1), N-opt 50kgha(-1) and N-f nonfertilized), and Ralja, where only N-l 100kgha(-1) was applied. Model calibration focused on the measured data (root depth, crop phenology, and the above-ground biomass by year of growth. Calibration results showed a very good match between measured and simulated values. The largest and only significant difference was noted in 2008, when the crop was establishing and exhibited uneven radication. The simulation results for the next 5years showed a variance from -4 to 5.7%, believed to be a very good match. A high coefficient of determination (R-2=0.995) and high Willmott index of agreement (0.998) were also indicative of a good match between simulated and recorded biomass yields. The measured and simulated results for validated datasets at both locations were good. The average RMSE was 2.89 Mgha(-1); when compared to the deviations noted at the test site itself, it was apparent that they were smaller in all the years of research except the first year. The index of agreement was 0.97 and the coefficient of determination R-2 0.947. The AquaCrop model can be used with a high degree of reliability in strategic planning of Miscanthus cultivation in new areas, under different nutrient and water supply and local weather and soil conditions