African Journal of Agricultural Economics and Rural Development

African Journal of Agricultural Economics and Rural Development ISSN 2375-0693 Vol. 2 (6), pp. 001-005, March, 2014. © International Scholars Journals

Full Length Research Paper

The influence of HCO₃^-, K⁺ and HSO₃^- on RUBISCO large-subunit (rbcL) and small-subunit (rbcS) genes expression

Jianjun Hao*, Lina Liu, Yang Yu and Ruizhi Zhou

College of Biological Science and Technology, Shenyang Agricultural University, Shenyang 110161, China.

Accepted 15 January, 2014

Abstract

KHCO₃ and NaHSO₃ were sprayed on the leaves of cucumber, and HCO₃^-, K⁺, HSO₃^- in liquor can accelerate the expression of ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO) large-subunit (rbcL) and RUBISCO small-subunit (rbcS) genes. These results proved that, mRNA content in the leaves of rbcL and rbcS was increased and the carboxylation activity of RUBISCO was also improved obviously, the content of RUBISCO has not increased but decreased. According to the analysis, we obtain that K⁺ ,HCO₃^-, HSO₃^- could affect the expression of rbcL and rbcS in a transcription way.

Key words: RUBISCO large-subunit (rbcL), RUBISCO small-subunit (rbcS) expression, RUBISCO.

African Journal of Agricultural Economics and Rural Development ISSN 2375-0693 Vol. 2 (6), pp. 001-005, March, 2014. © International Scholars Journals

Full Length Research Paper

Effect of some organic waste extracts on hatching of Meloidogyne incognita eggs

Osei K.¹*, Addico R.², Nafeo A.², Edu-Kwarteng A.¹, Agyemang A.¹, Danso Y.¹ and Sackey-Asante J.¹

¹Crops Research Institute, Box 3785, Kumasi, Ghana.

²West Africa Fair Fruit, PMB KD 11, Kanda, Accra, Ghana.

Accepted 08 January, 2014

Abstract

Plant parasitic nematodes significantly hinder food production particularly in the developing world where peasant farmers have little knowledge of these pests. Currently, synthetic pesticides which are highly detrimental to man and the environment are the principal means of nematode control. However, plant products might provide a sustainable control option as nematicidal properties have been identified in many higher plants. An in vitro experiment involving five organic waste extracts; citrus waste, cocoa bean testa, compost, poultry manure and oil palm bunch waste were therefore evaluated for their hatching inhibitory potential to the southern root-knot nematode, Meloidogyne incognita eggs. Three concentration levels (w/v) that is 4, 8 and 10% of cold aqueous extracts of the organic waste compounds were filtered into 9 cm Petri dishes and infested with 100 eggs each. Hatching of eggs was monitored over a three time period; 24, 48 and 72 h after infestation of the eggs into the cold aqueous extracts of the five candidates in Petri dishes. The best result was obtained with citrus waste extract in which 5 eggs hatched while 73 eggs hatched in the distilled water (the control treatment) representing a hatching reduction of 93% at the highest time and concentration of 72 h and 10% respectively.

Key words: Hatching, Meloidogyne incognita, organic waste extracts, plant parasitic nematodes.

African Journal of Agricultural Economics and Rural Development ISSN 2375-0693 Vol. 2 (6), pp. 001-006, March, 2014. © International Scholars Journals

Full Length Research Paper

Effects of insect population density and storage time on grain damage and weight loss in maize due to the maize weevil Sitophilus zeamais and the larger grain borer Prostephanus truncatus

Tadele Tefera¹*, Stephen Mugo¹ and Paddy Likhayo²

¹International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, UN Avenue, Gigiri, PO Box 1041, 00621 Village Market, Nairobi, Kenya.

²Kenya Agricultural Reserch Institute (KARI), National Agricultural Laboratories, Nairobi, Kenya.

Accepted 08 October, 2013

Abstract

A study was conducted with the objectives of assessing comparative grain damage and weight loss in maize due Prostephanus truncatus and Sitophilus zeamais at ten varying population densities (5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 insects per 200 g grain) and three storage durations (30, 60 and 90 days), in a laboratory. The final insect densities, percent grain damage, flour (dust) produced and weight loss due to P. truncatus exceeded that of the S. zeamais. Mean final insect population density, percent dust production, and weight loss increased over the storage period for P. truncatus. However, percent dust production and weight loss did not show significant increase over the storage time for S. zeamais. Percent grain damage declined 60 days after grain storage for P. truncatus. However, percent grain damage increased sharply over the storage period for S. zeamais. A mean weight loss of 67.1 and 6.9% recorded at an initial population density of 50 insects 200 g^-1 grain, after 90 days for P. truncatus and S. zeamais, respectively. Flour production by P. truncatus (52.8%) was higher than that of S. zeamais (1.2%) after 90 days due to extensive tunneling to the grain by the former. In conclusion, P. truncatus, caused high grain damage and weight loss, indicating that control measures should be designed at the onset of grain storage if the grain is planned to be stored for more than 30 days. Traditional grain storage facilities may not offer protection against P. truncatus, but promotion of the use of metal silos and resistant varieties in Kenya for grain storage is an alternative approach to reduce losses by P. truncatus.

Key words: Damage, dust, maize, population density, Prostepahnus truncatus; Sitophilus zeamais, storage time, weight loss.

African Journal of Agricultural Economics and Rural Development ISSN 2375-0693 Vol. 2 (6), pp. 001-006, March, 2014. © International Scholars Journals

Full Length Research Paper

Effects of concentration, frequency of application and runoff of foliar-applied soluble silicon on powdery mildew of zucchini

H. B. Tesfagiorgis* and M. D. Laing

School of Agricultural Sciences and Agribusiness, Discipline of Plant Pathology, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3201, South Africa.

Accepted 14 September, 2013

Abstract

The effect of concentration, frequency of application and runoff of foliar-applied soluble silicon (Si) on the severity of powdery mildew (PM) of zucchini (Cucurbita pepo L.) was evaluated. Soluble Si (250 to 1000 mgL^-1), together with Break-Thru^® (0.25 ml/L), was sprayed onto zucchini plants at frequencies of 1 to 3 times per week. The leaves of all plants were inoculated with a known concentration of conidia of Podosphaera xanthii 2 days after the sprays were applied. The effect of runoff was determined by covering some of the pots with polyethylene sheets, while others were left uncovered. Spraying Si onto zucchini plants reduced the severity of PM significantly. The efficacy of Si was improved by increasing the spray frequency. The best results were obtained when the frequency of the treatment was increased, and when Si was allowed to reach the root zone of the plants. When Si was applied onto leaves, direct contact between the spray and the pathogen seemed to be the main mechanism of action involved in disease control, and part of the spray (that is, the runoff) was absorbed by the plant roots, and subsequently played an important role in the health of the plants.

Key words: Podosphaera xanthii, powdery mildew, soluble silicon, zucchini.

African Journal of Agricultural Economics and Rural Development ISSN 2375-0693 Vol. 2 (6), pp. 001-008, March, 2014. © International Scholars Journals

Full Length Research Paper

Inoculation with Rhizobium etli enhances organic acid exudation in common bean (Phaseolus vulgaris L.) subjected to phosphorus deficiency

Maureen Fonji Atemkeng^1,2*, Roseline Remans², Jans Michiels², Appolinaire Tagne¹  and Eddy Leonard Mangaptche Ngonkeu¹

¹Annual Crop, Institute of Agricultural Research for Development (IRAD), Yaoundé, Cameroon.

²Centre of Microbial and Plant Genetics (CMPG), Katholieke Universiteit Leuven, Kasteelpark, Arenberg, Heverlee, Belgium.

Accepted 14 November, 2013

Abstract

Common bean (Phaseolus vulgaris L.) production is severely limited by phosphorus (P) deficiency in tropical and subtropical regions. Plants are known to exudate organic acids in order to survive in low nutrient environment. However, little is documented on the effect of inoculation on organic acids exudation by plants as a strategy to adapt to low P stress. In this study, the organic acids exuded by two bean genotypes (known to have contrasting symbiotic nitrogen fixation capacities) inoculated with Rhizobium etli and subjected to P deficiency were compared. The results showed that, under P deficiency, the P efficient genotype (BAT477) secretes higher amounts of organic acids serving as nutrient for Rhizobacteria or involved in P solubilisation. Furthermore, inoculation with R. etli under P deficiency strongly enhanced the exudation of oxalate and citrate by the P-efficient genotype. These effects of P-level and inoculation on root exudation were much less observed for the P-inefficient genotype (DOR364). This study indicated the difference in organic acid exudation between the two bean genotypes, especially in combination with Rhizobium inoculation which may contribute to the contrast in performance under P deficiency.

Key words: Phaseolus vulgaris, Rhizobia, root exudation, genotypic performance, phosphorus efficiency.

African Journal of Agricultural Economics and Rural Development ISSN 2375-0693 Vol. 2 (6), pp. 001-010, March, 2014. © International Scholars Journals

Full Length Research Paper

Effect of photosynthetic characteristic and dry matter accumulation of rice under high temperature at heading stage

X. J. Xie^1,2*, S. H. H. Shen¹, Y. X. Li¹, X. Y. Zhao¹, B. B. Li¹ and D. F. Xu¹

¹Jiangsu Key Laboratory of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing, Jiangsu Province, Peoples Republic of China.

²College of Applied Meteorology，Nanjing University of Information Science and Technology, Nanjing, Jiangsu Province, Peoples Republic of China.

Accepted 09 March, 2014

Abstract

The dry matter of rice grain mainly originates from photosynthetic outcome. The relationships between photosynthetic characteristic and dry matter accumulation were measured based on room experiments with two rice varieties (Yangdao6 and Nanjing43) under different high temperature stress of heading stage in 2007 and 2008. The results showed that grain yield, chlorophyll content, net photosynthetic rate (NPn), superoxide dismutase activity (SOD) and leaf area index (LAI) suffered a sharply decline. On the other hand, relative conductivity and malondialdehyde content (MDA) increased gradually with the elevation of stress temperature and extension of stress time. The increasing rate (reducing rate) of some physiological and biochemical indexes in Yangdao6 were lower than that in Nanjing43 compared with the CK under the same temperature stress. It was shown that response of Nanjing43 to high temperature was bigger than that of Yangdao6. According to the correlation analysis, grain yield showed a positive correlation with NPn and LAI at 0.01 level, the correlation coefficients of them were 0.94 and 0.88 respectively. The correlation between grain yield and DW after initial at mature stage, the export percentage of the matter in stem-sheath (EPMSS) and the transformation percentage of the matter in stem-sheath (TPMSS) were not significant. It was showed that grain yield under high temperature stress originated mostly from the photosynthesis and LAI of leaves after heading stage.

Key words: Dry matter, heading stage, high temperature stress, photosynthetic characteristic, rice.