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Volume 5 Number 6 June 2019

Effects of Potassium Fertilization for Pineapple on Internal Browning of Fruit in Post-Harvest Conservation


Authors: Coulibaly Souleymane ; Yapo Sopie Edwige-Salomé ; N’cho Achi Laurent ; Kouadio Oi Kouadio Samuel ; Kouakou Tanoh Hilaire
Pages: 100-108
DOI: doi.org/10.32861/jac.56.100.108
Abstract
Resistance to internal browning of pineapple fruits depends on several factors such as the cultural techniques through mineral fertilization. The objective of this work is to study the effects of the potassium fertilization for pineapple on internal browning of fruit in post-harvest conservation. The experiments have been carried out on the site of the University Nangui Abrogoua (Abidjan, Côte d’Ivoire) of July 2015 to the end of October 2016. Potassium has been applied according to four modalities of treatments (T0; T1; T2 and T3) made in 2nd, 4, 6 and 7th months (respectively) after plantation. The incidence of internal browning (IB), the phenolic content, sugars and ascorbic acid have been determined after post-harvest conservation of fruit. The activity of phenolic biosynthesis enzymes (PAL and TAL) and oxidation enzymes (PPO and POD) were evaluated. The results showed that BI intensity in pineapple fruit decreases with the potassium amount applied in field. This IB drop was correlated with the content of reducing sugars, total phenols, activity of PAL and the PPO. No symptom of IB was observed on pineapple fruits under treatment T2 (34 g of K2O/plant). Potassium has a depressive effect on phenolic biosynthesis. In effect, it inhibits the IB in the both varieties of pineapple studied that are Smooth Cayenne and MD2.

Intercropping and Fertilizer Rate Combinations Impact on Maize (Zea Mays L.) and Soybean (Glycine Max L (Merill)) Productivity: The Case Study in the Guinea Savannah Agro-Ecological Zone of Ghana


Authors: Joseph Xorse Kugbe ; Isaac Kwahene Addai ; Karl Anyetin-Nya Asekabta
Pages: 87-99
DOI: doi.org/10.32861/jac.56.87.99
Abstract
Production of food in resource-constrained environments that have poor inherent soil nutrition depends on tillage and cropping systems that provide high yields, preserve soil, water and biodiversity. This research was conducted in the Guinea savannah agroecology of Ghana, during the 2015-2016 cropping seasons to evaluate the impact of tillage and cropping systems on sustainable production of maize and soybean by resource-poor farmers. The experiment was a split-split plot design with four replications. The factors consisted of tillage system at three levels (plough, ripping and direct-seeding) laid out as main plots, fertilizer rate at three levels (0 kg/ha, half the recommended rate of 30-15-15 kg/ha and the recommended optimum rate of 60-30-30 kg/ha NPK) laid as sub-plots and cropping system at two levels (sole maize, maize-soybean intercrop) laid on the sub-sub plot. Apart from leaf area that had significant three-way interaction of tillage, cropping system and fertilizer rate (p < 0.05), all other growth parameters were affected by either two factor interaction or a sole factor. Grain yield of maize was significantly influenced by sole maize and fertilizer rate with highest yield occurring under the full rate (3.4 t/ha) compared with the half rate (2.7 t/ha), amounting to yield difference of about 700 kg/ha. Yield of soybean under the integrated production was affected by interaction of tillage system and fertilizer rate. Highest soybean yield (1.4 t/ha) was recorded under the ploughed condition at the full rate of fertilizer application. Though sole maize, ploughed and with full rate of fertilizer application, gave similar benefit/cost ratio as that of the integrated production with half rate of fertilizer application, the intercropped system with half fertilizer rate resulted in 45% more increases in profit compared to the sole production with full fertilizer rate. Integrated production of maize and soybean, with half the recommended rate of NPK (30-15-15 kg/ha) is therefore recommended to resource-poor farmers in northern Ghana.

Comparative Assessment of Phosphorus Fertilization and Rhizobia Inoculation on Soybean Production in the Guinea Savanna Zone of Ghana


Authors: Sam Ebenezer Kofi ; Kugbe Xorse Joseph ; Adu-Gyamfi Raphael ; Odoom Asooming Daniel ; Laryea Obodia Kenneth ; Asodewine Peter
Pages: 78-86
DOI: doi.org/10.32861/jac.56.78.86
Abstract
In the Guinea savannah zone of northern Ghana, the soils are reported to be declining for agricultural productivity. In these farming communities that depend on soybean production for their livelihoods, resource-poor farmers are not able to afford purchases of high cost inorganic phosphatic fertilizers to enhance the crop’s production. The need arises to identify efficient practices and strategies and research into alternative means of enhancing soybean production to improve food security. This Randomized Complete Block Design as an experimental tool was employed to carry out a research in the Guinea savanna zone of Ghana (Tolon District) to assess the agronomic and economic productivity of rhizobia inoculation use in soybean production.  Treatments used for the experiment were sole soybean production, soybean + recommended phosphorus (P) fertilize rate, soybean + inoculums, and soybean + P + inoculum. A planting distance of 60*10cm was used during planting. Each treatment was replicated three times. Growth and yield data were collected on plant height, nodule number and dry weight, shoot dry weight, pods number and dry weight, grain yield, 100 seed weight and nodule effectiveness. The results revealed the existence of significant difference in grain yield between treatments (p = 0.011). Soybean + inoculation + P gave the highest yield of 3.6 t/ha followed by soybean + inoculation (3.17 t/ha), soybean + P (2.97 t/ha) and soybean only (2.6 t/ha) respectively.  Significant difference was also observed for number of pods between treatments (p= 0.01), with soybean + inoculation + phosphorus recording the highest followed by soybean + inoculation, soybean + phosphorus and soybean-only treatment respectively. However, use of sole inoculation in soybean production was associated with the least production cost, high revenue generation and high benefit/cost ratio. As rhizobia inoculation of soybean produced higher yields and is comparatively cheaper than phosphorus application, inoculation is suggested for the resource poor farmer in Northern Ghana.

Effect on the Growth and Nutritional Components in Two Red Lettuces (Lactuca sativa L.) Cultivated Under UV Light in a Mini Plant Factory


Authors: Cindy Mayorga ; Satoru Tsukagoshi ; Anna Sasaki
Pages: 71-77
DOI: doi.org/10.32861/jac.56.71.77
Abstract
Lettuce is one of the most suitable plant species to grow indoor or in a Plant Factory with Artificial lighting (PFAL) system, due to its short height and the relatively low light saturation point. Red lettuces are highly cultivated in PFALs, highly appreciated for its unique pigmentation and antioxidant activity, especially, the anthocyanin content that gives it the red color. However, red lettuces cultivated with PFAL in controlled environments face the challenge of having low anthocyanin content due of the lack of ultraviolet (UV) light that is necessary for its production. In this study, two red-lettuce cultivars ‘Annapolis’ and ‘Salanova’ were grown in a plant factory with LEDs (light-emitting diode) and UV light treatments to compare their growth trajectory and nutritional characteristics. Other characteristics such as Fresh Weight (FW) and total leaf area were measured to evaluate the influence of UV light in the lettuce growth. The nutritional quality of lettuces was assessed by measuring anthocyanins and polyphenols contents using a microplate reader and their ascorbic acid content measured via a reflectometer. Fresh Weight (FW), leaf area and leaf thickness under the conditions of this study, showed no effect (p>0.05) on the plants growth with the incorporation of UV radiation. However, the incorporation of UV light increased the functional components in ‘Annapolis’ and ‘Salanova’ lettuces. The polyphenol and anthocyanins contents in both lettuce cultivars showed significant differences (p<0.05). For ascorbic acid content, a significant difference was found only for ‘Annapolis’ lettuce. The incorporation of UV light can increase the functional ingredients such as polyphenols and anthocyanins without growth suppression for ‘Salanova’ cultivar. UV light increased polyphenol and anthocyanins contents in both cultivars, making them suitable cultivars for PFAL under the growth conditions used in this experiment.  These results taken together can be used to improve the accumulation of functional ingredients in red lettuces without growth suppression incorporating UV light and that could be suitable for production in PFALs.