African Journal of Tropical Agriculture

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 8 (3), pp. 001-004, March, 2020. © International Scholars Journals

Full Length Research Paper

Assessment of physical properties of gum arabic from Acacia senegal varieties in Baringo District, Kenya

J. K. Lelon¹*, I. O. Jumba², J. K. Keter², Wekesa Chemuku and F. D. O. Oduor²

¹Kenya Forestry Research Institute (KEFRI), P. O. Box 20412-00200, Nairobi, Kenya.

²University of Nairobi, P. O. Box 30197-00100, Nairobi, Kenya.

Accepted 09 December, 2019

Abstract

A study was conducted to assess the physical properties of gum arabic obtained from two Acacia senegal varieties (var.senegal and var.kerensis). in Marigat division, Baringo district. Gum arabic samples from the experimental sites at Solit, Kapkun, Kimorok and Maoi were collected, dried and analysed to establish their physical characteristics. Moisture content in gum arabic obtained from variety kerensis in Kimorok and Maoi (17.5 ± 1.00 and 15.4 ± 0.50%) were significantly higher (P < 0.05) than those of variety senegal in Solit and Kapkun (15.0 ± 0.50 and 14.9 ± 1.80%), while internal energy (33.4 and 33.76%) were not significantly different (P > 0.05) from those of variety senegal found in Kapkun and Solit (33.0 and 32.96%), respectively. Ash content in gum arabic from variety senegal in Solit and Kapkun (2.94 and 3.16%) was higher (P < 0.05) than those of variety kerensis found in Kimorok and Maoi (2.88 and 2.72%). In Kapkun, volatile matter in gum arabic from variety senegal (64.2%) was higher (P < 0.05) than the quantities of variety kerensis found in Kimorok, Solit and Maoi (63.8, 63.7 and 63.6%), respectively. Moisture content in gum arabic from variety senegal in Solit and Kapkun (15.0 ± 0.40 and 14.9 ± 1.80%) fell within international specifications (13 to 15%), while variety kerensis in Kimorok and Maoi (17.5 and 15.4%) fell outside the specifications. Moisture, ash and volatile matter contents in gum arabic from A. senegal variety senegal were 14.9, 3.16 and 64.24%, while A. senegal variety kerensis had 15.2, 2.88 and 63.8%, respectively. Moisture content in gum arabic from A. senegal variety senegal fell within international specifications while A. senegal variety kerensis fell outside the specifications. Ash, volatile matter and internal energy contents in gum arabic from A. senegal variety kerensis and variety senegal fell within the specifications. The gum arabic from A. senegal variety senegal in Solit and Kapkun was of better quality than that of A. senegal variety kerensis in Kimorok and Maoi.

Key words: Study sites, Acacia senegal varieties, physical properties, gum quality.

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 8 (3), pp. 001-013, March, 2020. © International Scholars Journals

Full Length Research Paper

Application of a satellite-based climate-variability impact index for crop yield forecasting in drought-stricken regions

Ping Zhang¹*, Bruce Anderson², Mathew Barlow³, Bin Tan¹ and Ranga B. Myneni²

¹Earth Resource Technology Inc., Annapolis Junction, MD, 20701, USA.

²Department of Geography, Boston University, Boston, MA, 02215, USA.

³Environmental, Earth and Atmospheric Sciences, University of Massachusetts Lowell, Lowell, MA, 01854, USA.

Accepted 05 January, 2020

Abstract

A quantitative index is applied to monitor crop growth and predict agricultural yield in drought-stricken regions. This Climate-Variability Impact Index (CVII), defined as the monthly contribution to overall anomalies in growth during a given year, is derived from 1 km MODIS Leaf Area Index. The CVII integrated over the growing season represents the percentage of the climatological production either gained or lost due to climatic variability during a given year and is positively correlated with crop yields. In two test cases presented here, a statistical model is trained using the historical CVII and yield records and is then applied to predict crop yields for Illinois in 2005 as well as North and South Dakota in 2006. The model predictions are consistent with USDA’s estimates obtained after harvesting. Since the CVII are available in near real-time, the model predictions can also be obtained monthly before the end of the growing season. The in-season CVII model shows predictability comparable to the concurrent NASS estimates. In addition, these model forecasts improve as more CVII series are added in the late season. Finally, this research highlights the need for explicit monitoring of vegetation growth when estimating yield as drought-monitoring indices such as the Standardized Precipitation Index can both overestimate and underestimate implied changes in vegetation in drought-stricken regions.

Key words: Remote sensing, leaf area index, crop monitoring, early yield forecast, drought index, climate impacts.

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 8 (3), pp. 001-015, March, 2020. © International Scholars Journals

Full Length Research Paper

S₁ selection of local maize landraces for low soil nitrogen tolerance in Zambia 

Francisco Miti^1*, Pangirayi Tongoona² and John Derera²

¹Seed Control and Certification Institute (SCCI), Ministry of Agriculture and Cooperatives, P. O. Box 350199, Chilanga, Zambia.

²University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, South Africa.

Accepted 13 September, 2019

Abstract

Low soil nitrogen (N) limits maize production in Zambia. S₁ selection was used to select for tolerance to low N among ninety-six maize landraces during 2004 - 2007 in Zambia. The landraces were evaluated under low N, drought and optimal conditions; and selfed in a nursery, under optimal conditions. Data on grain yield (GY), number of ears per plant, leaf senescence and anthesis-silking interval were used to calculate selection indices. Fourteen S₁ lines, from each of the best four landraces under each environment and across all environments were evaluated under the three environments, and at the same time crossed to a tester. Twenty-two best S₁ lines under each environment and across were identified and also their testcrosses were evaluation under the three environments. Significant GCA effects for GY under low soil N were found; suggesting that population improvement under soil N stress was effective. Heritability for GY under low soil N conditions was low (0.38) implying that selection based on GY was ineffective. The r_G for GY under low soil N and optimal environments was moderate (0.458), suggesting that selection for GY in one environment was not as effective as in the other. Low soil N tolerant landraces were identified and should be used to breed for the low soil N conditions.

Key words: Maize, landrace, heritability, correlation, nitrogen, tolerance, stress.

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 8 (2), pp. 001-006, February, 2020. © International Scholars Journals

Full Length Research Paper

Degradation of fungal cell walls of phytopathogenic fungi by lytic enzyme of Streptomyces griseus

A. Anitha¹* and M. Rabeeth²

¹Department of Biotechnology, Kongunadu Arts and Science College, G. N. Mills Post, Coimbatore - 641 029, Tamil Nadu, India.

²Zoology department, Chikkanna Government Arts College, Tiruppur - 641 602, Tamil Nadu, India.

Accepted 22 November, 2019

Abstract

In vitro tests of interactions between Streptomyces griseus strains and some soil-borne plant pathogens (Fusarium oxysporum, Alternaria alternate, Rhizoctonia solani and Fusarium solani) and 2 isolates of Aspergillus flavus were studied on PDA medium. Strains tested produced a metabolite that inhibited growth of plant pathogenic fungi on PDA medium (dual culture test). When grown in liquid medium having fungal cell walls as sole carbon source, S. griseus produced chitinase enzyme in the medium. Higher levels of this enzyme were induced by cell wall of Aspergillus flavus and the crude chitinase enzyme extracted showed zone of inhibition on all pathogens inoculated PDA plates at all tested concentrations. When lytic enzyme produced by S. griseus was incubated with hyphal wall of the test fungi treated with 2 M NaOH and chloropharm: Methanol, the release of glucose and N acetyl glucosamine significantly increased relative to the untreated one. This result suggests that proteins in the cell walls of pathogens may make these walls more resistant to degradation by the extracellular lytic enzymes. Ionic strength of NaOH on lytic activity was tested, where as the enzymes lysed fungal cell wall best at ionic concentration of 2 M treatment. Pretreatment with alkali or proteolytic enzyme increases their susceptibility for lysis. In vitro lytic activity provides an appropriate condition and the effect of biocontrol organism in field level treatment.

Key words: Chitinase enzyme, dual culture test, plant pathogenic fungi, NaOH treatment and Ionic strength.

African Journal of Tropical Agriculture ISSN 2375-091X Vol. 8 (2), pp. 001-008, February, 2020. © International Scholars Journals

Full Length Research Paper

How fertilization affects yam (Dioscorea alata L.) growth and tuber yield across the years

V. K. Hgaza^{1, 2*}, L. N. Diby^{2, 3}, A. Assa⁴ and S. Ake¹

¹Laboratory of Plant Physiology, UFR Biosciences, University of Cocody-Abidjan, Côte d’Ivoire.

²Swiss Center for Scientific Research, Abidjan, Côte d’Ivoire.

³Department of Water Forest and Environment, National Institute of Technology FHB, Yamoussoukro, Côte d’Ivoire.

⁴Deceased, Laboratory, of soil science, UFR STRM, University of Cocody-Abidjan, Côte d’Ivoire.

Accepted 18 September, 2019

Abstract

This study deals with the response of Dioscorea alata to NPK-Ca fertilization as affected by differences in weather conditions in two growing seasons. Experiments were conducted in the central Côte d’Ivoire in 2006 and 2007. The experimental design was a randomised complete block design with 4 replications. The dose of 160- 10-180-110 kg ha^-1 of NPK-Ca, respectively was compared to the control (no fertilizers applied). Growth parameters and weather conditions were measured during the growth periods. Rainfall and solar radiation varied much between the two years. Fertilization has significantly increased the tuber yield of both years. In 2006, however, this increase in aboveground organs dry matter was not reflected in tuber dry matter increase, suggesting possible physiological imbalance in which fertilizer has favoured top growth over the tubers. This resulted in higher leaf area index and lower fresh tuber yield. This physiological imbalance could be related to higher water supply during the vegetative period in 2006. Although the weather conditions varied much between years, the leaf area index and the fresh tuber yield were similar between years under non-fertilization, indicating a good adaptation of D. alata to low soil fertility across the year. Explanations are needed to understand source (leaves) - sink (tubers) relationship in yam and investigation to clarify implications of mineral fertilizers in this important process is warranted.

Key words: Dry matter partitioning, fertilization, leaf area index, radiation use efficiency, water distribution, year.