African Journal of Agricultural Research 

About: African Journal of Agricultural Research is an academic journal published by Academic Journals. The journal publishes majorly in the area(s): Population & Agriculture. It has an ISSN identifier of 1991-637X. It is also open access. Over the lifetime, 6506 publications have been published receiving 64390 citations. The journal is also known as: AJAR.

The Assistat Software Version 7.7 and its use in the analysis of experimental data

Abstract: Statistical programs are essential tools for those who deal with scientific research and need to analyze experimental data. In agriculture, there are often uncontrolled factors, which determine the necessity of statistical analyses of the data. The Assistat software version 7.7 is one of these tools and this study aimed to demonstrate its functionality and efficiency in the analyses of experimental data of agricultural research and evaluate its acceptance. In order to exemplify its utilization, data of agricultural experiments were analyzed using the models of analysis of variance for randomized block and factorial experiments. In addition, the regression was used in the analysis of variance for quantitative treatments. It was concluded that the software was used in many papers published in journals and that it is functional and efficient in the analysis of experimental data of agricultural research. Key words: Analysis of variance (ANOVA), statistical software, Tukey's test.

Morphological, physiological and biochemical responses of plants to drought stress

Abstract: Plants in nature are continuously exposed to several biotic and abiotic stresses. Among these stresses, drought stress is one of the most adverse factors of plant growth and productivity and considered a severe threat for sustainable crop production in the conditions on changing climate. Drought triggers a wide variety of plant responses, ranging from cellular metabolism to changes in growth rates and crop yields. Understanding the biochemical and molecular responses to drought is essential for a holistic perception of plant resistance mechanisms to water-limited conditions. This review describes some aspects of drought induced changes in morphological, physiological and biochemical changes in plants. Drought stress progressively decreases CO2 assimilation rates due to reduced stomatal conductance. It reduces leaf size, stems extension and root proliferation, disturbs plant water relations and reduces water-use efficiency. It disrupts photosynthetic pigments and reduces the gas exchange leading to a reduction in plant growth and productivity. The critical roles of osmolyte accumulation under drought stress conditions have been actively researched to understand the tolerance of plants to dehydration. In addition, drought stress-induced generation of active oxygen species is well recognized at the cellular level and is tightly controlled at both the production and consumption levels, through increased antioxidative systems. This review focuses on the ability and strategies of higher plants to respond and adapt to drought stress. Key words: Drought stress, growth, yield, gas exchange, photosynthetic pigments, antioxidative system.

Production of bioethanol from sweet sorghum: A review

Abstract: The consumption of bioethanol as biofule may reduce greenhouse gases, gasoline imports. Also it can be replaced with lead or MTBE (Methyl tert-butyl ether) that are air and underground water pollutants, respectively. Plants are the best choice for meeting the projected bioethanol demands. For this scope, a comparative analysis of the technological options using different feedstocks should be performed. Our research and other studies indicate that sweet sorghum can be used as a feedstock for ethanol production under hot and dry climatic conditions. Because, it has higher tolerance to salt and drought comparing to sugarcane and corn that are currently used for biofuel production in the world. In addition, high carbohydrates content of sweet sorghum stalk are similar to sugarcane but its water and fertilizer requirements are much lower than sugarcane. Also, sugarcane is not a salt tolerant plant. On the other hand, high fermentable sugar content in sweet sorghum stalk makes it to be more suitable for fermentation to ethanol. Therefore, it is suggested to plant sweet sorghum for biofule production in hot and dry countries to solve problems such as increasing the octane of gasoline and to reduce greenhouse gases and gasoline imports. Key words: Sweet sorghum, carbohydrate, bioethanol, biofuel.

Assessment of Drought Tolerance in Segregating Populations in Durum Wheat

Abstract: Wheat improvement for drought tolerance requires reliable assessment of drought tolerance variability among segregating populations. One hundred and fifty-one F3 and F4families of durum wheat derived from a cross between Oste-Gata (as drought tolerance) and Massara-1 (as susceptible) genotypes were evaluated both under moisture stress (E1) and non-stress (E2) field environments using a randomized complete block design for each environment and growing season (2003-04, 2004-05). Entries of E1 were subjected to moisture stress at grain filling period. Five drought tolerance indices comprising: stress tolerance index (STI), stress tolerance (TOL), stress susceptibility index (SSI), mean productivity (MP), and geometric mean productivity (GMP) were used. The indices were adjusted based on grain yield under drought (Ys) and normal (Yp) conditions. Analysis of variance for each individual year showed that there was a significant genetic variation among families for all criteria with the exception of SSI. The combined analysis of variance over seasons indicated the genetic diversity of lines, significant variation of seasons and differential response of genotypes over seasons for all indices with the exception of SSI. The significant and positive correlations of Yp and (MP, GMP and STI) and Ys and (MP, GMP and STI) under both the seasons as well as significant negative correlation of SSI and TOL in E1 revealed that selection could be conducted for high MP, GMP and STI under both environments and low SSI and TOL under E1conditions. The calculated correlation coefficients revealed that STI, MP, and GMP are the superior criteria for selection of high yielding genotypes both under E1 and E2. Cluster analysis of families using Ys, Yp and five other indices categorized genotypes into five groups each of which having 37, 56, 13, 34 and 11 genotypes in year 2003-04 growing season, respectively. Based on 2004-05 growing season data, six groups each of which having 25, 9, 25, 45, 10 and 37 genotypes were obtained, respectively. Cluster analysis distinguished groups contains superior lines for both E1 and E2, superior lines for only E1 conditions and superior lines for E2 conditions, considering their yield performance (Yp and Ys). Results of calculated gain from indirect selection indicated that selection from moisture stress environment would improve yield in moisture stress environment better than selection from non-moisture stress environment. The comparison of the number of families in common within the top 25% families at E1 in year 2004-05 and those selected using various indices indicated that drought tolerant indices could perform comparable with yield performance (Yp and Ys). Key words: Durum wheat, Moisture stress, Drought tolerance index, grain yield.

Biocontrol potentiality of plant growth promoting bacteria (PGPR) - Pseudomonas fluorescens and Bacillus subtilis: A review

Abstract: Plant growth in agricultural soils is influenced by many abiotic and biotic factors. There is a thin layer of soil immediately surrounding plant roots that is an extremely important and active area for root activity and metabolism which is known as rhizosphere. The rhizosphere concept was first introduced by Hiltner to describe the narrow zone of soil surrounding the roots where microbe populations are stimulated by root activities. A large number of microorganisms such as bacteria, fungi, protozoa and algae coexist in the rhizosphere. Bacteria are the most abundant among them. Plants select those bacteria contributing most to their fitness by releasing organic compounds through exudates creating a very selective environment where diversity is low. Since, bacteria are the most abundant microorganisms in the rhizosphere, it is highly probable that they influence the plants physiology to a greater extent, especially considering their competitiveness in root colonization. The present review deals with the following topics: Plant growth promoting rhizobacteria (PGPR), occurrence of PGPR, nitrogen fixation by PGPR, Bacillus species, Pseudomonas species, Production of plant growth promoting substances by PGPR isolates, PGPR as biocontrol agent and antagonistic activity of PGPR isolates against phytopathogens. Key words: Biocontrol, plant growth promoting rhizobacteria (PGPR), Pseudomonas fluorescens, Bacillus subtilis.