Low cost maize stover biochar as an alternative to inorganic fertilizer for improvement of soil chemical properties, growth and yield of tomatoes on degraded soil of Northern Uganda.

BACKGROUND: Soil fertility decline due to nutrient mining coupled with low inorganic fertilizer usage is a major cause of low crop yields across sub-Saharan Africa. Recently, biochar potential to improve soil fertility has gained significant attention but there are limited studies on the use of biochar as an alternative to inorganic fertilizers. In this study, we determined the effect of maize stover biochar without inorganic fertilizers on soil chemical properties, growth and yield of tomatoes (Solanum lycopersicum L.). A field experiment was conducted in 2022 for two consecutive seasons in Northern Uganda. The experiment included five treatments; inorganic fertilizer (control), biochar applied at rates of 3.5, 6.9, 13.8 and 27.6 t ha-1. RESULTS: In this study, maize stover biochar improved all the soil chemical properties. Compared to the control, pH significantly increased by 27% in the 27.6 t ha-1 while total N increased by 35.6% in the 13.8 t ha-1. Although P was significantly low in the 3.5 t ha-1, 6.9 t ha-1 and 13.8 t ha-1, it increased by 3.9% in the 27.6 t ha-1. Exchangeable K was significantly increased by 42.7% and 56.7% in the 13.8 t ha-1 and 27.6 t ha-1 respectively. Exchangeable Ca and Mg were also higher in the biochar treatment than the control. Results also showed that plant height, shoot weight, and all yield parameters were significantly higher in the inorganic fertilizer treatment than in the 3.5, 6.9, and 13.8 t ha-1 treatments. Interestingly, maize stover biochar at 27. 6 t ha-1 increased fruit yield by 16.1% compared to the control suggesting it could be used as an alternative to inorganic fertilizer. CONCLUSIONS: Maize stover biochar applied at 27.6 t ha-1 improved soil chemical properties especially pH, N, P and K promoting growth and yield of tomatoes. Therefore, maize stover biochar could be recommended as an alternative to expensive inorganic fertilizers for tomato production in Northern Uganda.

The genotype-dependent phenotypic landscape of quinoa in salt tolerance and key growth traits.

Cultivation of quinoa (Chenopodium quinoa), an annual pseudocereal crop that originated in the Andes, is spreading globally. Because quinoa is highly nutritious and resistant to multiple abiotic stresses, it is emerging as a valuable crop to provide food and nutrition security worldwide. However, molecular analyses have been hindered by the genetic heterogeneity resulting from partial outcrossing. In this study, we generated 136 inbred quinoa lines as a basis for the molecular identification and characterization of gene functions in quinoa through genotyping and phenotyping. Following genotyping-by-sequencing analysis of the inbred lines, we selected 5,753 single-nucleotide polymorphisms (SNPs) in the quinoa genome. Based on these SNPs, we show that our quinoa inbred lines fall into three genetic sub-populations. Moreover, we measured phenotypes, such as salt tolerance and key growth traits in the inbred quinoa lines and generated a heatmap that provides a succinct overview of the genotype-phenotype relationship between inbred quinoa lines. We also demonstrate that, in contrast to northern highland lines, most lowland and southern highland lines can germinate even under high salinity conditions. These findings provide a basis for the molecular elucidation and genetic improvement of quinoa and improve our understanding of the evolutionary process underlying quinoa domestication.

Exogenous Kinetin Promotes the Nonenzymatic Antioxidant System and Photosynthetic Activity of Coffee (Coffea arabica L.) Plants Under Cold Stress Conditions.

Coffee plants are seasonally exposed to low chilling temperatures in many coffee-producing regions. In this study, we investigated the ameliorative effects of kinetin-a cytokinin elicitor compound on the nonenzymatic antioxidants and the photosynthetic physiology of young coffee plants subjected to cold stress conditions. Although net CO2 assimilation rates were not significantly affected amongst the treatments, the subjection of coffee plants to cold stress conditions caused low gas exchanges and photosynthetic efficiency, which was accompanied by membrane disintegration and the breakdown of chlorophyll pigments. Kinetin treatment, on the other hand, maintained a higher intercellular-to-ambient CO2 concentration ratio with concomitant improvement in stomatal conductance and mesophyll efficiency. Moreover, the leaves of kinetin-treated plants maintained slightly higher photochemical quenching (qP) and open photosystem II centers (qL), which was accompanied by higher electron transfer rates (ETRs) compared to their non-treated counterparts under cold stress conditions. The exogenous foliar application of kinetin also stimulated the metabolism of caffeine, trigonelline, 5-caffeoylquinic acid, mangiferin, anthocyanins and total phenolic content. The contents of these nonenzymatic antioxidants were highest under cold stress conditions in kinetin-treated plants than during optimal conditions. Our results further indicated that the exogenous application of kinetin increased the total radical scavenging capacity of coffee plants. Therefore, the exogenous application of kinetin has the potential to reinforce antioxidant capacity, as well as modulate the decline in photosynthetic productivity resulting in improved tolerance under cold stress conditions.

Phytochemical Profile and Antioxidant Capacity of Coffee Plant Organs Compared to Green and Roasted Coffee Beans.

The current study investigates the phytochemical composition of coffee plant organs and their corresponding antioxidant capacities compared to green and roasted coffee beans. HPLC analysis indicated that the investigated compounds were present in all organs except mangiferin, which was absent in roots, stems and seeds, and caffeine, which was absent in stems and roots. Total phytochemicals were highest in the green beans (GB) at 9.70 mg g-1 dry weight (DW), while roasting caused a 66% decline in the roasted beans (RB). This decline resulted more from 5-CQA and sucrose decomposition by 68% and 97%, respectively, while caffeine and trigonelline were not significantly thermally affected. Roasting increased the total phenolic content (TPC) by 20.8% which was associated with an increase of 68.8%, 47.5% and 13.4% in the antioxidant capacity (TEAC) determined by 2,2-diphenyl-1-picryl hydrazyl radical (DPPH), 2,2-azino bis (3-ethyl benzothiazoline-6-sulphonic acid) radical (ABTS) and Ferric ion reducing antioxidant power (FRAP) assays, respectively. Amongst the leaves, the youngest (L1) contained the highest content at 8.23 mg g-1 DW, which gradually reduced with leaf age to 5.57 mg g-1 DW in the oldest (L6). Leaves also contained the highest TPC (over 60 mg g-1 GAE) and exhibited high TEAC, the latter being highest in L1 at 328.0, 345.7 and 1097.4, and least in L6 at 304.6, 294.5 and 755.1 µmol Trolox g-1 sample for the respective assays. Phytochemical accumulation, TPC and TEAC were least in woody stem (WS) at 1.42 mg g-1 DW; 8.7 mg g-1 GAE; 21.9, 24.9 and 110.0 µmol Trolox g-1 sample; while herbaceous stem (HS) contained up to 4.37 mg g-1 DW; 27.8 mg g-1 GAE; 110.9, 124.8 and 469.7 µmol Trolox g-1 sample, respectively. Roots contained up to 1.85 mg g-1 DW, 15.8 mg-1 GAE and TEAC of 36.8, 41.5 and 156.7 µmol Trolox g-1 sample. Amongst the organs, therefore, coffee leaves possessed higher values than roasted beans on the basis of phytochemicals, TPC and TEAC. Leaves also contain carotenoids and chlorophylls pigments with potent health benefits. With appropriate processing methods, a beverage prepared from leaves (coffee leaf tea) could be a rich source of phytochemicals and antioxidants with therapeutic and pharmacological values for human health.

Gene expression changes triggered by end-of-day far-red light treatment on early developmental stages of Eustoma grandiflorum (Raf.) Shinn.

To better understand the molecular mechanisms related to growth promotion in the early developmental stages of Eustoma grandiflorum (Raf.) Shinn. under end-of-day far-red light (EOD-FR) treatment, we analyzed the leaf transcriptome of treated (EOD) and untreated plants (Cont) by using RNA-seq technology. EOD-FR treatment for only about 2 weeks in regions with limited sunshine during winter resulted in significantly higher internode length between the 3rd and 4th nodes on the main stem in EOD than in Cont. Among the differentially expressed genes (DEGs) related to synthesis or transport of auxin, higher levels of YUCCA (CL6581) and PIN4 (CL6181) were noted after treatment in EOD than in Cont in the leaf. In addition, high expression levels of GA20ox (Unigene11862) related to gibberellin (GA) synthesis and transcription factor bHLH 135 (CL7761) were observed in the stem of EOD, 3 h after treatment. A vertical section of the stem showed that the pith length of cells at the 4th node was longer in EOD than in Cont. Collectively, these results suggested that EOD-FR treatment increased the expression of DEGs related to GA and auxin biosynthesis, bHLH transcription factor, and internodal cell elongation along the longitudinal axis of Eustoma plants.

Production and characterization of cyanocobalamin-enriched lettuce (Lactuca sativa L.) grown using hydroponics.

When lettuces (Lactuca sativa L.) grown for 30 days in hydroponic culture were treated with various concentrations of cyanocobalamin for 24 h, its content in their leaves increased significantly from nondetectable to 164.6 ± 74.7 ng/g fresh weight. This finding indicated that consumption of only two or three of these fresh leaves is sufficient to meet the Recommended Dietary Allowance for adults of 2.4 µg/day. Analyses using a cobalamin-dependent Escherichia coli 215 bioautogram and LC/ESI-MS/MS demonstrated that the cyanocobalamin absorbed from the nutrient solutions by the leaves did not alter any other compounds such as coenzymes and inactive corrinoids. Gel filtration indicated that most (86%) of the cyanocobalamin in the leaves was recovered in the free cyanocobalamin fractions. These results indicated that cyanocobalamin-enriched lettuce leaves would be an excellent source of free cyanocobalamin, particularly for strict vegetarians or elderly people with food-bound cobalamin malabsorption.

Effects of various asparagus production methods on rutin and protodioscin contents in spears and cladophylls.

The purpose of this study was to clarify the relationship between various cultivation conditions and the amounts of the rutin (RT) and protodioscin (PD) in asparagus spears. Green and white spears were grown in open culture and under two different blanching conditions. Although RT was detected only in the green spears, PD was detected mainly in white spears produced by covering with soil. The RT and PD contents of cladophylls grown in an open field and in a closed cultivation system were also investigated, and the closed system resulted in cladophylls with low RT and high PD, unlike the open field.

An evaluation of aerobic and anaerobic composting of banana peels treated with different inoculums for soil nutrient replenishment.

This study sought to evaluate the efficacy of aerobic and anaerobic composting of inoculated banana peels, and assess the agronomic value of banana peel-based compost. Changes in the chemical composition under aerobic and anaerobic conditions were examined for four formulations of banana peel-based wastes over a period of 12 weeks. The formulations i.e. plain banana peel (B), and a mixture with either cow dung (BC), poultry litter (BP) or earthworm (BE) were separately composted under aerobic and anaerobic conditions under laboratory conditions. Inoculation with either cow dung or poultry litter significantly facilitated mineralization in the order: BP>BC>B. The rate of decomposition was significantly faster under aerobic than in anaerobic composting conditions. The final composts contained high K (>100 g kg(-1)) and TN (>2%), indicating high potential as a source of K and N fertilizer.

A heat-stable extract from Mucuna stimulates the differentiation of bone marrow cells into dendritic cells and induces apoptosis in cancer cells.

Pine cone extract is known to induce differentiation of human mononuclear cells into dendritic cells (DCs) and also to induce apoptosis in human cancer cells. In the present study, we screened edible plants that contain components with biological activities similar to or more potent than those of pine cone extract. We found that Mucuna (Mucuna pruviens var. utilis) contains a DC differentiation/maturation-inducing activity and a component that induces apoptosis in human cancer cell lines. Mucuna extract specifically stimulated differentiation of BM cells to immature DCs. Marked production of IL-6 was observed by sequential treatment with at least 10 µg/mL of Mucuna extract followed by LPS. The sequential treatment with Mucuna extract followed by LPS produced a much higher ratio of IL-12 to IL-6 and a lower ratio of TNF-α to IL-6 than that obtained by sequential treatment with a medicinal mushroom Phellinus linteus extract and then LPS. The DC differentiation/maturation activity and the component inducing apoptosis in cancer cells were separable by column chromatography.

Reduction of cadmium uptake in spinach (Spinacia oleracea L.) by soil amendment with animal waste compost.

A field experiment was conducted to evaluate the efficacy of animal waste compost (AWC) in reducing Cd uptake by spinach (Spinacia oleracea L.). Spinach was grown in a field that had been treated by having cattle, swine, or poultry waste compost incorporated into the soil before each crop throughout 4 years of rotational vegetable production. Cadmium concentration was 34-38% lower in spinach harvested from the AWC-treated soils than in the chemical fertilizer-treated soil. Although the repeated application of swine and poultry compost caused significant P accumulation in the cropped soils, that of cattle compost did not. These results indicate that cattle compost with high affinity for Cd and low P content should be the preferred soil amendment when used to reduce Cd uptake by spinach.

Role of 5-aminolevulinic acid (ALA) on active oxygen-scavenging system in NaCl-treated spinach (Spinacia oleracea).

ALA is a key precursor in the biosynthesis of porphyrins such as chlorophyll and heme, and was found to induce temporary elevations in the photosynthesis rate, APX, and CAT; furthermore, treatment with ALA at a low concentration might be correlated to the increase of NaCl tolerance of spinach plants. The photosynthetic rate and the levels of active oxygen-scavenging system in the 3rd leaf of spinach (Spinacia oleracea) plants grown by foliar treatment with 0, 0.18, 0.60 and 1.80 mmol/L 5-aminolevulinic acid under 50 and 100 mmol/L NaCl were analyzed. Plants treated with 0.60 and 1.80 mmol/L ALA showed significant increases in the photosynthetic rate at 50 and 100 mmol/L NaCl, while that of 0.18 mmol/L ALA did not show any changes at 50 mmol/L NaCl and a gradual decrease at 100 mmol/L NaCl. In contrast, the rate with 0 mmol/L ALA showed reduction at both concentrations of NaCl. The increase of hydrogen peroxide content by treatment with 0.60 and 1.80 mmol/L ALA were more controlled than that of 0 mmol/L ALA under both NaCl conditions. These ALA-treated spinach leaves also exhibited a lower oxidized/reduced ascorbate acid ratio and a higher reduced/oxidized glutathione ratio than the 0 mmol/L-treated spinach leaves when grown at both NaCl conditions. With regard to the antioxidant enzyme activities in the leaves, ascorbate peroxidase, catalase, and glutathione reductase activities were enhanced remarkably, most notably at day 3, by treatment with 0.60 and 1.80 mmol/L ALA under both NaCl conditions in comparison to that of 0 and 0.18 mmol/L ALA. These data indicate that the protection against oxidative damage by higher levels of antioxidants and enzyme activities, and by a more active ascorbate-glutathione cycle related to the increase of the photosynthesis rate, could be involved in the increased salt tolerance observed in spinach by treatment with 0.60 to 1.80 mmol/L ALA with NaCl.