scholarly journals Genetic variability in Colletotrichum gloeosporioides (Penz.) isolated from cassava and yam from four agro-ecological zones of Ghana

2015 ◽  
Vol 5 (4) ◽  
pp. 132-140
Author(s):  
Z. Appiah-Kubi ◽  
◽  
A. K. Apetorgbor ◽  
E. Moses ◽  
M. Quian ◽  
...  
Keyword(s):  
Genetic Variability ◽  
Colletotrichum Gloeosporioides ◽  
Ecological Zones ◽  
Agro Ecological Zones

scholarly journals Agro-ecological distribution of the phenotypic diversity of aerial yam (Dioscorea bulbifera L.) in Cameroon using multivariate analysis: prospect for germplasm conservation and improvement

2018 ◽  
Vol 3 (1) ◽  
pp. 190-206 ◽  
Author(s):  
Eric B. Kouam ◽  
Marie L. Avana-Tientcheu ◽  
Vanessa D. Lekeumo ◽  
Hermine M. Akitio ◽  
Damase P. Khasa ◽  
...  
Keyword(s):  
Multivariate Analysis ◽  
Genetic Variability ◽  
Phenotypic Diversity ◽  
Germplasm Conservation ◽  
Group Method ◽  
Crop Species ◽  
Humid Forest ◽  
Ecological Zones ◽  
Dioscorea Bulbifera ◽  
Agro Ecological Zones

Abstract Aerial yam (Dioscorea bulbifera L.) is a crop of great economic importance and an excellent candidate for improving food security in developing countries. Understanding the genetic variability of any crop species is a decisive step for its improvement and requires characterization and evaluation of available germplasm. The objectives of this study were to determine the extent of genetic variability, estimate the association between agromorphological traits and clustering among 57 genotypes of aerial yam from three distinct agro-ecological zones in Cameroon using multivariate analysis. Thirty nine characters (23 qualitative and 16 quantitative) were used for the study. Significant differences in genetic diversity indices were found. Accessions from the bimodal humid forest zone (Na = 2.08, He = 0.27) showed significantly lower diversity compared to both western highland (Na = 2.30, He = 0.34) and humid monomodal forest zones (Na = 2.57, He = 0.32). Means values of most quantitative traits also showed significant differences between agro-ecological zones. Batingla-3 and Bawouwoua-1 had important bulbil yield, reaching 3500 g / plant. Significant associations were found between many traits. The use of the Unweighted Pair Group Method with Arithmetic Mean allowed the distribution of the 57 genotypes into six distinct clusters with the clustering pattern not showing any parallelism with location sites or agro-ecological zones. Mahalanobis D2 statistics revealed the highest inter-cluster distance between cluster II and VI. Accessions of these clusters are potential parents for future breeding programs. This study showed that aerial yam from Cameroon has an enormous wealth of traits variation, indicating huge potential for its genetic improvement through selection and hybridization.

scholarly journals Variability of Colletotrichum gloeosporioides Isolates the Causal Agent of Anthracnose Disease of Cassava and Yam Plants in Ghana

2016 ◽  
Vol 5 (1) ◽  
pp. 01-09 ◽  
Author(s):  
Zippora Appiah-Kubi ◽  
Apetorgbor A. Kofi ◽  
Moses Emmanuel ◽  
Appiah-Kubi David ◽  
Marfo Esther
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Random Amplified Polymorphic Dna ◽  
Economic Loss ◽  
Growth Characteristics ◽  
Sub Saharan Africa ◽  
Causal Organism ◽  
Ecological Zones ◽  
Anthracnose Disease ◽  
Plant Parts ◽  
Agro Ecological Zones

Cassava and yam plants are important staple foods of millions of people in the tropical world and provide food security in most parts of sub-Saharan Africa. Their production however is affected by anthracnose disease caused by Colletotrichum gloeosporioides, (Penz.) Penz. and Sacc contributing to 30-70% economic loss in both crops. A study was carried out to determine if variations exist between isolates of C. gloeosporioides on the two crops occurring in different agro-ecological zones of Ghana.  Anthracnose-diseased samples of cassava and yam plant parts (leaves and stem/vine) were collected from four agro-ecological zones of Ghana (Forest, Forest-Savannah Transition, Guinea and Coastal Savannah). Isolations of the causal organism C. gloeosporioides were made. The isolates were investigated on the basis of growth characteristics on Potato Dextrose Agar (PDA): presence or absence of setae, colour of cultures, dimensions of conidia. Pathogenicity of isolates was determined and molecular analysis conducted using Random Amplified Polymorphic DNA (RAPD). Results showed both similarities and variations in cultural, morphological and growth characteristics of the pathogen. Isolates from yam caused pathogenic lesions on cassava and yam plant sections and vice versa.  Forty-four isolates of C. gloeosporioides from cassava and yam compared by RAPD analysis grouped the isolates into three main clusters. Within two of the clusters are six polymorphic sub-groups relating to host and geographical origin. The different polymorphic sub-groups indicated that there are several sub-populations of C. gloeosporioides isolates, which either singly or in association, involved in the yam and cassava anthracnose infections in the field. Isolates from different ecological zones, with similar morphological features, clustering in a polymorphic sub-group suggest a common origin for some of them.

scholarly journals Towards Understanding Variability in Droughts in Response to Extreme Climate Conditions over the Different Agro-Ecological Zones of Pakistan

2021 ◽  
Vol 13 (12) ◽  
pp. 6910
Author(s):  
Adil Dilawar ◽  
Baozhang Chen ◽  
Arfan Arshad ◽  
Lifeng Guo ◽  
Muhammad Irfan Ehsan ◽  
...  
Keyword(s):  
Pearson Correlation ◽  
Principal Component ◽  
Mitigation Strategies ◽  
Precipitation Extremes ◽  
Climate Mitigation ◽  
Mean Annual Temperature ◽  
Climate Extreme ◽  
Ecological Zones ◽  
The Mean ◽  
Agro Ecological Zones

Here, we provided a comprehensive analysis of long-term drought and climate extreme patterns in the agro ecological zones (AEZs) of Pakistan during 1980–2019. Drought trends were investigated using the standardized precipitation evapotranspiration index (SPEI) at various timescales (SPEI-1, SPEI-3, SPEI-6, and SPEI-12). The results showed that droughts (seasonal and annual) were more persistent and severe in the southern, southwestern, southeastern, and central parts of the region. Drought exacerbated with slopes of −0.02, −0.07, −0.08, −0.01, and −0.02 per year. Drought prevailed in all AEZs in the spring season. The majority of AEZs in Pakistan’s southern, middle, and southwestern regions had experienced substantial warming. The mean annual temperature minimum (Tmin) increased faster than the mean annual temperature maximum (Tmax) in all zones. Precipitation decreased in the southern, northern, central, and southwestern parts of the region. Principal component analysis (PCA) revealed a robust increase in temperature extremes with a variance of 76% and a decrease in precipitation extremes with a variance of 91% in the region. Temperature and precipitation extremes indices had a strong Pearson correlation with drought events. Higher temperatures resulted in extreme drought (dry conditions), while higher precipitation levels resulted in wetting conditions (no drought) in different AEZs. In most AEZs, drought occurrences were more responsive to precipitation. The current findings are helpful for climate mitigation strategies and specific zonal efforts are needed to alleviate the environmental and societal impacts of drought.

Stock and stability of organic carbon in soils under major agro-ecological zones and cropping systems of sub-tropical India

2021 ◽  
Vol 312 ◽  
pp. 107317
Author(s):  
Nirmalendu Basak ◽  
Biswapati Mandal ◽  
Ashim Datta ◽  
Manik Chandra Kundu ◽  
Arvind Kumar Rai ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Cropping Systems ◽  
Ecological Zones ◽  
Agro Ecological Zones

scholarly journals Comparative Experimental Effects of Intercropping and Cypermethrin on Insect Pest Infestation and Yield of Maize, Cowpea and Okra in Two Cameroonian Agro-Ecological Zones

2021 ◽  
Vol 3 (2) ◽  
pp. 383-393
Author(s):  
Patient Farsia Djidjonri ◽  
Nukenine Elias Nchiwan ◽  
Hartmut Koehler
Keyword(s):  
Field Experiments ◽  
Insect Pests ◽  
Cropping Systems ◽  
Insect Pest ◽  
Maize Yield ◽  
Ecological Zones ◽  
Pest Infestation ◽  
Final Yield ◽  
Cropping Seasons ◽  
Agro Ecological Zones

The present study investigates the effect of intercropping (maize-cowpea, maize-okra, maize-okra-cowpea, okra-cowpea) compared to insecticide application on the level of infestation of insect pests and the final yield of maize, cowpea and okra. Field experiments were conducted during the 2016 and 2017 cropping seasons in the Guinean Savannah (Dang-Ngaoundere) and Sudano Sahelian (Gouna-Garoua) agro-ecological zones in Cameroon. Our experimental design was a split plot arrangement in a randomized complete block with four replications. The main factor was assigned to the use of insecticide (Cypermethrin) and sub plots were devoted for cropping systems. We compared the efficiency of intercropping to that of Cypermethrin application on the Yield of maize, cowpea and okra as influenced by insect pest damages. The comparison of monocropped sprayed by Cypermethrin to unsprayed showed that, in Dang, insect pests reduced maize yield by 37% and 24% in 2016 and 2017, respectively, whereas in Gouna, it was lower than 8% during the both years. Reduction in seed yield by insect pests on cowpea in Dang represented 47% and 50% in 2016 and 2017, respectively, whereas in Gouna, it was 55% and 63% in 2016 and 2017, respectively. For okra, insect pests reduced okra fruit yield by 25% and 44% in Dang and 23% and 28% in Gouna, respectively, in 2016 and 2017. Crop yield was lower in intercropping compared to monoculture due to competition of plants in association on different resources. Considering the total yields obtained from each intercropping, intercropping trials resulted generally in higher yields compared to mono-culture (LER > 1) in both sites and years but the respective yields were quite different. On the basis of the results obtained, we recommend maize-cowpea intercropping as a sustainable solution to reduce the infestation level of their pest insects.

Evaluation of potential crop productivity based on remote sensing and agro-ecological zones around the world

2017 ◽  
Vol 33 (7) ◽  
pp. 713-722
Author(s):  
Hongyan Wang ◽  
Qiangzi Li ◽  
Xin Du ◽  
Longcai Zhao ◽  
Na Wang
Keyword(s):  
Remote Sensing ◽  
Crop Productivity ◽  
Ecological Zones ◽  
The World ◽  
Agro Ecological Zones

Evaluation of GRACE derived groundwater storage changes in different agro-ecological zones of the Indus Basin

2021 ◽  
pp. 127369
Author(s):  
Fazlullah Akhtar ◽  
Rana Ali Nawaz ◽  
Mohsin Hafeez ◽  
Usman Khalid Awan ◽  
Christian Borgemeister ◽  
...  
Keyword(s):  
Indus Basin ◽  
Groundwater Storage ◽  
Ecological Zones ◽  
Agro Ecological Zones
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