Root Biomass Yield Research Articles

Hormetic response of blackgram (Vigna mungo) seeds treated with organic extract of seaweeds

Seaweed extract has gained popularity in agriculture due to global trend of promoting sustainable agricultural development. Seaweed contains phytohormones such as IAA and gibberellin and minerals that induce seeds germination. While conventional extraction of seaweeds has been carried out with different organic solvents such as ethanol and methanol, the present study uses natural and commonly available organic liquids i.e., water, vinegar, fermented buttermilk, and cow urine as extracting agents to make them suitable for regenerative agriculture. The organic solvents used in this study have a known nutritional composition and facilitate the enhancement of plant defense systems. Three seaweed species, Caulerpa racemosa, Gracilaria edulis, and Sargassum wightii, were extracted with different solvents at various concentrations and compared. The mineral analysis and FTIR characterization of different seaweeds and their extracts showed variation in composition and functional groups. Seaweed species, however, showed no variation in seed germination. Fermented buttermilk and water extract improved the germination properties of blackgram between 0.1–5% concentrations and led to higher increase in shoot and root length and biomass yield. The hormetic response by blackgram to the seaweed extract was observed starting at an average of 2% concentration with toxicity at 5% concentration and above for water and fermented buttermilk extract. However, vinegar and cow urine extracted seaweed showed toxicity symptoms even at lower concentrations (0.1%) inhibiting germination. Therefore, water and buttermilk extract may be recommended at 0.5–1% for enhanced germination.

How Does No-till Affect Soil-Profile Distribution of Roots?

No-till (NT) often causes prominent stratification of C and nutrients in the soil profile relative to tilled systems. We hypothesize differences in root distribution within the soil profile between NT and tilled systems could be one factor contributing to stratification. We evaluated how NT affects root length density (RLD), root biomass yield (RBY), and root diameter compared with other tillage systems and factors that may affect root characteristics. We reviewed studies until 23 January 2024 where RLD, RBY, or root diameter were reported under NT and tillage. The data on RLD, RBY, and diameter were tabulated and the weighted log response ratio (MLRR) and confidence intervals computed. Our meta-analysis showed NT increased RLD in the 0-10 cm depth, but reduced RLD at 10-20 cm. It increased RBY and diameter in the 0-20 cm depth and reduced both characteristics at 20-30 cm. Regardless of root characteristic, NT had mixed effects below 30 cm. However, across the soil profile (minimum 50 cm depth), NT had no effect on RLD and RBY. No-till-induced changes in roots can be related to increased compaction at the tillage interface. No-till stratified both RLD and RBY compared with high intensity tillage systems, although there were some conditions where NT stratified only RLD or RBY. No-till did not induce stratification of RLD and RBY in dry regions, mild or hot climates, in medium-textured soils, or compared with intermediate intensity tillage systems. Overall, NT can result in stratification of both RBY and RLD compared with high intensity tillage systems.

Increasing the planting density of Cryptolepis sanguinolenta (Lindl.) Schlt increased root biomass and cryptolepine yield

Cryptolepis sanguinolenta (Lindl.) Schlt. is an important multipurpose medicinal plant used for the treatment of ailments such as malaria. Despite the ongoing efforts in domesticating the herb, the ideal planting density and its benefits are unknown. A study was conducted to determine the influence of six C. sanguinolenta accessions and three planting densities (15, 30 and 45 plants/1.8 m2) on root biomass, cryptolepine concentration and cryptolepine yield. Also, benefit-cost ratios were determined for each plant density across the four cultivation periods (9, 12, 15 and 18 months). The cultivation of C. sanguinolenta at the highest planting density (45 plants/1.8 m2) increased root biomass (value), cryptolepine content (2.08 mg/100 mg dry root) and cryptolepine yield (23.31 mg mg/1.8 m2) compared to those cultivated at lower planting densities (15 and 30 plants/1.8 m2). The duration for growing C. sanguinolenta had a more significant influence on cryptolepine yield but not the cryptolepine content. Plants cultivated for 15 months gave the maximum cryptolepine yield (10.33 g/bed), indicating 15 months as the optimum time to harvest the roots. The benefit-cost analysis revealed that growing the plant at a density of 45 plants/1.8 m2 (25,920 plants/acre) for 18 months was a more profitable venture with a benefit-cost ratio of 3.45. Commercial cultivation of C. sanguinolenta at 45 plants per bed area of 1.8 m2 (25,920 plants/acre) for 15–18 months is recommended as the most profitable and promising cropping practice to ensure the sustainable supply of planting material.

Response of yield, root traits and plasticity of nitrogen-efficient cultivars of drip-irrigated rice to a nitrogen environment

The response of drip-irrigated rice physiological traits to water and fertilisers has been widely studied. However, the responses of yield, root traits and their plasticity to the nitrogen environment in different nitrogen-efficient cultivars are not fully understood. An experiment was conducted from 2020-2022 with high nitrogen efficient (high-NUE) cultivars (T-43) and low-NUE cultivars (LX-3), and four nitrogen levels (0, 150, 300, and 450 kg ha-1) under drip irrigation in large fields were used. The aim was to study the relationship between root morphology, conformation, biomass, and endogenous hormone content and yield and nitrogen use efficiency. The results showed the following: 1) Under the same N application rate, compared with LX-3, T-43’s yield, N partial factor productivity (PFP), fine root length density (FRLD), shoot dry weight (SDW), root indole-3-acetic acid (IAA), and root zeatin and zeatin riboside (Z+ZR) were significantly increased by 11.4-18.9%, 11.3-13.5%, 11.6-15.7%, 9.9-31.1%, 6.1-48.1%, and 22.8-73.6%, respectively, while the root-shoot ratio (RSR) and root abscisic acid (ABA) were significantly decreased (P<0.05). 2) Nitrogen significantly increased rice root morphological indexes and endogenous hormone contents (P<0.05). Compared to N0, yield, root length density (RLD), surface area density (SAD), Root volume density (RVD), and root endogenous hormones (IAA, Z+ZR) were significantly increased in the 2 cultivars under N2 by 61.6-71.6%, 64.2-74.0%, 69.9-105.6%, 6.67-9.91%, 54.0-67.8%, and 51.4-58.9%, respectively. Compared with N3, the PFP and N agronomic efficiency (NAE) of nitrogen fertiliser under N2 increased by 52.3-62.4% and 39.2-63.0%, respectively. 3) The response of root trait plasticity to the N environment significantly differed (P<0.05). Compared with LX-3, T-43 showed a longer root length and larger specific surface area, which is a strategy for adapting to changes in the nutrient environment. For rice cultivars with high-NUE, the root-shoot ratio was optimised by increasing the FRLD, root distribution in upper soil layers, and root endogenous hormones (IAA, Z+ZR) under suitable nitrogen conditions (N2). An efficient nutrient acquisition strategy can occur through root plasticity, leading to increased yield and NUE.

Effect of different diesel treatments on growth of single and mixed plant communities and petroleum hydrocarbon dissipation during rhizoremediation

The use of mixed plant communities has been proposed to address phytotoxicity while improving plant stress tolerance and contaminant degradation. However, there has been conflicting findings on the use of mixed plant community. This study assessed the impact of three diesel treatments on plant growth and TPH dissipation in single and mixed plant communities. This involved greenhouse experiment with Medicago sativa, Festuca arundinacea, and Lolium perenne and Medicago sativa + Lolium perenne with the diesel-spiked soils at 102,000, 151,000 and 320,000 µg kg-1 TPH represented as Treatments 1, 2 and 3 respectively. Plant growth was inhibited with root biomass yield was greater compared to plant shoots especially for F. arundinacea and L. perenne. There was a significant decrease in the root biomass yield of M. sativa, L. perenne, F. arundinacea and M. sativa + L. perenne. The highest TPH dissipation of 81, 69 and 72 % was displayed by L. perenne in the Treatments 1, 2 and 3 respectively. However, TPH dissipation was generally comparable for the vegetated and unvegetated soil and were not significantly different (p&gt;0.05) for the different plants and treatments. The impact of plant communities on the rhizoremediation of TPH-contaminated soils may dependent on factors such as plant species, TPH concentration stress tolerance and benefits of individual plant if mixed plants are to be employed.

Comparing the Grain Yields and Other Properties of Old and New Wheat Cultivars

Selecting cultivars with greater biomass results in higher yields and greater carbon sequestration. Storage of atmospheric carbon in the plant/soil pool contributes not only to food security but also to mitigating climate change and other agroecological benefits. The objective of this study was to determine: (1) grain, residue, and root biomass yields; (2) harvest indexes; (3) residue-to-product ratio; (4) root-to-shoot ratio; (5) biomass carbon and nitrogen contents; and (6) C:N ratios for two new and two old winter wheat cultivars. The greatest yield difference was found between old Srpanjka (the lowest) and new Kraljica (the highest) cultivar where grain, residue, root, and total biomass yield was higher by 38%, 91%, 71%, and 64%, respectively. Total biomass was composed of 40–47% grain, 10–11% roots, 32–36% stems + leaves, 9–11% chaff, and 1–2% spindle. The range of HI was 0.45–0.53, RPR 0.91–1.25, and R:S ratio 0.12–0.13. For all cultivars, positive carbon and negative nitrogen balance within the plant pool was determined. Still, root biomass and rhizodeposition carbon remain open questions for a better understanding of agroecosystems’ C dynamics.

Genetic diversity for drought tolerance in the native forage grass Trichloris crinita and possible morpho-physiological mechanisms involved.

The use of drought tolerant genotypes is one of the main strategies proposed for coping with the negative effects of global warming in dry lands. Trichloris crinita is a native forage grass occupying extensive arid and semi-arid regions in the American continent, and used for range grazing and revegetation of degraded lands. To identify drought-tolerant genotypes and possible underlying physiological mechanisms, this study investigated drought tolerance in 21 genetically diverse T. crinita genotypes under natural field conditions. The accessions were grown under irrigated (control) and drought conditions for 84 days after initiation of the drought treatment (DAIDT), which coincided with flowering initiation. Various morpho-physiological traits were monitored, including total-, foliage-, and root biomass yield, dry matter partitioning to individual plant organs (roots, leaves, stems, and panicles), total leaf area, chlorophyll content, photochemical efficiency of photosystem II, stomatal conductance, and number of panicles per plant. Broad and significant variation (p<0.001) was found among the accessions for all the traits. Three highly tolerant and three very sensitive accessions were identified as the most contrasting materials, and their responses to drought stress were confirmed over two years of experiments. Under prolonged drought conditions (84 DAIDT), the tolerant accessions were generally more productive than the rest for all the biomass yield components analyzed, and this was associated with a postponed and more attenuated decrease in variables related to the plant photosynthetic activity, such as stomatal conductance, chlorophyll content, and photochemical efficiency. In contrast to previous findings, our data indicate no direct relationship between drought tolerance and the level of aridity in the accessions natural habitats, but rather suggest genetic heterogeneity and ample variation for drought tolerance in T. crinita natural populations derived from a particular location or environment. Also, having low total and forageable biomass yield, or increased biomass allocation to the roots (i.e., lower foliage/root ratio), under optimal water availability, were not associated with greater drought tolerance. The drought-tolerant accessions identified are of value for future genetic research and breeding programs, and as forage for range grazing and revegetation in arid regions.

Root nodulation and yield of French bean (Phaseolus vulgaris) are altered by fallow length in slash-and-burn agriculture

ABSTRACT Shifting cultivation (Jhum) involves the conversion of forest land to agricultural land, and two successive Jhum cultivations in a patch of land make a Jhum cycle. Shortening of the cycle to meet population needs is a challenge, and one potential solution is to use N2-fixing, trees in fallow-phase and crops in cropping-phase. A pot experiment was conducted with soil from 2-, 4-, and 8-years fallows of alder-based (N2-fixed) and traditional Jhum agroecosystems, grown with surface-sterilized local French beans (design: CRD). A factorial micro-plot field experiment was also set up in alder-based Jhum sites in 2-, 4-, and 8-years fallow. In both, soil physico-chemical and biological properties, root nodulation and yield attributes of French beans were studied. Root nodulation and biomass yield attributes were higher in alder-based systems compared to traditional, with comparable improvements seen in shorter fallows. At harvest, yield parameters were in the order of 4->2->8-years in alder-based and 8->4->2-years in traditional Jhum soil. Rhizobium populations may decrease with longer fallow lengths without a host and fire stress of Jhum. Fallow length effect on all soil parameters, with increased values as length increased in both Jhum. Combination of soil-fertility and nodulation led to higher grain yield in 4-year-fallows of alder-based Jhum.

Utilização de microrganismos multifuncionais na cultura do milho

ABSTRACT In the composition of the soil microbiome, there are numerous microorganisms capable of promoting plant growth, better known as plant growth-promoting microorganisms. The study aimed to determine the effects of multifunctional microorganisms, alone or in combination, on shoot, root, and total biomass production, gas exchange, macronutrient content, yield components, and grain yield of corn plants. The experiment was carried out in a greenhouse in a completely randomized design, with four replications. Twenty-six treatments consisted of isolated or combined microbiolization of corn seeds with the rhizobacteria Bacillus sp. (BRM 32109, BRM 32110, and BRM 63573), Burkholderia cepacea (BRM 32111), Pseudomonas sp. (BRM 32112), Serratia marcenses BRM 32113, Serratia sp. (BRM 32114), Azospirillum brasilense (Ab-V5), and Azospirillum sp. (BRM 63574), an isolated of fungus Trichoderma koningiopsis (BRM 53736), and a control treatment (without the application of microorganisms). At seven and 21 days, two more applications of the same treatments were carried out in the soil and the plants, respectively. The microorganisms applied alone or in combination promoted significant increases of 49% in corn plant biomass, 30% in gas exchange, 36% in macronutrient content, and 33% in grain yield. Isolates BRM 32114, Ab-V5, BRM 32110, and BRM 32112 and the combinations BRM 32114 + BRM 53736, BRM 63573 + Ab-V5, and BRM 32114 + BRM 32110 promoted better benefits to corn, allowing us to infer that the use of beneficial microorganisms significantly affects the development of corn plants.

Soil respiration in response to biotic and abiotic factors under different mulching measures on rain-fed farmland

Mulching measures strongly affect the soil physicochemical properties and crop growth. However, the effects of crop growth and the soil environment under mulching on soil respiration (Rs) and its components (Rh: heterotrophic respiration; Ra: autotrophic respiration) are still unclear. Therefore, in this study, we conducted an experiment in a maize field for five consecutive years with different mulching measures in a rain-fed area of China (P: flat planting with full plastic film mulching; R: ridge–furrow with half plastic film mulching; S: flat planting with full straw mulching; and CK: conventional tillage without mulching). The changes in the Rs, Rh, Ra, soil physicochemical properties, and microbial communities were monitored. The results showed that compared with CK, Rs increased by 37.4% under P, 20.3% under R, and 24.6% under S, and Rh and Ra increased by 768–1257 kg C ha–1 year–1 and 278–678 kg C ha–1 year–1, respectively. Among all of the treatments, the largest increases in the soil respiration emission fluxes and their components occurred under P. Plastic film mulching (P and R) significantly increased the aboveground biomass, leaf area index (LAI), root biomass, and grain yield in maize, whereas S had different effects on maize growth in different years. In addition, mulching significantly changed the soil physicochemical properties comprising the soil temperature, soil water content, NO3–, dissolved organic carbon, and microbial biomass carbon. Structural equation modeling showed that these physicochemical properties explained 89% of the variability in Ra and 71% of the variability in Rh. In addition, the changes in the Rs, Rh, and Ra rates were influenced by the soil bacterial diversity (Shannon diversity) and relative abundances of certain bacterial community members (Proteobacteria, Acidobacteria, Actinobacteria, Gemmatimonadetes, and Firmicutes). In summary, our results demonstrate that the Rs components were strongly influenced by SWC, ST, NO3–, and the soil microbial community. In particular, the increased soil carbon emissions under mulching were mainly due to Rh, and Rh was highly sensitive to the changes in precipitation. P obtained the highest soil carbon emissions and maize yield among all treatments, whereas S had a poor effect on increasing the yield. Considering climate warming and food security issues, R performed best.

Prevalence Of Nematode Population In Two Different Rice Cultivation Systems And Its Impact On Crop Growth

An experiment was carried out to study the prevalence of nematode population in two different cultivation systems (SRI and conventional) on rice cv. IET- 4094 (Khitish). Total twenty-eight plots were laid out in paired plot technique. Irrespective of rice cultivation systems, there had been a steady hike in population of Meloidogyne graminicola and Tylenchorhynchus mashhoodi with the maximum being recorded near harvest and a sudden fall during fallow period was observed. The study indicated that SRI cultivation provided comparatively more favourable ecological condition for steady buildup of M. graminicola and T. mashhoodi population than conventional system. Between two systems, SRI method encountered comparatively more population of Hoplolaimus indicus. The spiral nematode, Helicotylenchus dihystera was also found associated with the rice crop but statistical analysis did not reveal any stable result to come into conclusion about their ecological preference. The study revealed that continuous submergence of rice field as in conventional system was detrimental to growth and reproduction of R. reniformis. The rice crop grown under SRI method acquired more vigorous growth as compared to conventional system. Profuse root and shoot growth as evidenced by root length, root biomass yield and straw yield in SRI might have limit the yield reduction in spite of huge infestation of nematodes.

Root biomass and cumulative yield increase with mowing height in Festuca pratensis irrespective of Epichloë symbiosis

Increasing agricultural soil carbon sequestration without compromising the productivity of the land is a key challenge in global climate change mitigation. The carbon mitigation potential of grass-based agriculture is particularly high because grasslands represent 70% of the world’s agricultural area. The root systems of grasses transfer large amounts of carbon to below-ground storage, and the carbon allocation to the roots is dependent on the grasses’ photosynthesizing shoot biomass. In a common-garden experiment, Festuca pratensis was used as a model species to study how mowing and weed control practices of perennial cool-season fodder grasses affect total yield and root biomass. Additionally, grass-associated Epichloë endophytes and soil residual glyphosate were tested for their effect on the total yield and root biomass alone or in interaction with mowing. The results demonstrate that elevating the cutting height increases both cumulative yield and root biomass in F. pratensis. Endophyte symbiosis increased the total yield, while glyphosate-based herbicide residues in the soil decreased the root biomass, which indicates a reduction of soil bound carbon sequestration. The findings demonstrate that carbon sequestration and yield quantities on farmed grasslands may significantly be improved by optimizing strategies for the use of plant protection products and adjustment of mowing intensity.

Drought stress modifies the community structure of root-associated microbes that improve Atractylodes lancea growth and medicinal compound accumulation.

Atractylodes lancea is an important medicinal plant in traditional Chinese medicine, its rhizome is rich of volatile secondary metabolites with medicinal values and is largely demanded in modern markets. Currently, supply of high-yield, high-quality A. lancea is mainly achieved via cultivation. Certain soil microbes can benefit plant growth, secondary metabolism and induce resistance to environmental stresses. Hence, studies on the effects of soil microbe communities and isolates microorganisms on A. lancea is extremely meaningful for future application of microbes on cultivation. Here we investigated the effects of the inoculation with an entire soil microbial community on the growth, resistance to drought, and accumulation of major medicinal compounds (hinesol, β-eudesmol, atractylon and atractylodin) of A. lancea. We analyzed the interaction between A. lancea and the soil microbes at the phylum and genus levels under drought stress of different severities (inflicted by 0%, 10% and 25% PEG6000 treatments). Our results showed that inoculation with soil microbes promoted the growth, root biomass yield, medicinal compound accumulation, and rendered drought-resistant traits of A. lancea, including relatively high root:shoot ratio and high root water content under drought. Moreover, our results suggested drought stress was more powerful than the selectivity of A. lancea in shaping the root-associated microbial communities; also, the fungal communities had a stronger role than the bacterial communities in protecting A. lancea from drought. Specific microbial clades that might have a role in protecting A. lancea from drought stress were identified: at the genus level, the rhizospheric bacteria Bacillus, Dylla and Actinomadura, and rhizospheric fungi Chaetomium, Acrophialophora, Trichoderma and Thielava, the root endophytic bacteria Burkholderia-Caballeronia-Paraburkholderia, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Dylla and Actinomadura, and the root endophytic fungus Fusarium were closely associated with A. lancea under drought stress. Additionally, we acquired several endophytic Paenibacillus, Paraburkholderia and Fusarium strains and verified they had differential promoting effects on the medicinal compound accumulation in A. lancea root. This study reports the interaction between A. lancea and soil microbe communities under drought stress, and provides insights for improving the outcomes in A. lancea farming via applying microbe inoculation.

Adventitious root cultures of Arnebia euchroma: A sustainable alternative for the production of natural pigments

Arnebia euchroma is a valuable Himalayan herb, whose roots are savagely harvested from the wild to extract red naphthoquinone pigments with applications in food, cosmetic and pharmaceutical industries. The primary objective of this study was to induce A. euchroma adventitious roots and use the same for the production of naphthoquinone pigments. A number of media and auxin types were tried for the formation of adventitious roots from leaves of A. euchroma under in vitro conditions. The data showed 100% root induction on semi-solid Schenk & Hildebrandt (SH) medium fortified with 2.5 mg/L indole-3-butyric acid (IBA) after 4-weeks of culture. Thereafter, factors like inoculum density and sucrose concentration were optimized to maximize adventitious root growth and pigment production in liquid shake flask cultures. The results revealed a significantly high root biomass (7.00 ± 0.25 g/L dry weight (DW)) and pigment (192.92 ± 1.61 mg/g DW) yield in SH medium having 10 g/L inoculum density, 0.5 mg/L IBA and 5% sucrose concentration. In addition, the cultivation of adventitious roots in Balloon-Type Bubble Bioreactor (5 L cap.) was also done, which showed comparably lower root biomass (4.33 ± 0.09 g/L DW) yield to shake flask culturing, however, resulted in higher pigments accumulation (195.36 ± 1.95 mg/g DW). The chemical profile of in vitro induced adventitious roots cultivated in shake flask and bioreactor was also compared with parent plant rhizome using Ultra Performance Liquid Chromatography. As per the results, deoxyshikonin and β, β-dimethylacrylshikonin were found to be the key pigments in adventitious roots, although shikonin was not detectable which otherwise also present in parent plant rhizomes. Considering the shorter cultivation cycle (4-weeks) and regenerative potential of induced adventitious roots along with comparable metabolic profile, the developed process seems to be a feasible alternative for the production of natural pigments.

Comparative Genetic Diversity Analysis for Biomass Allocation and Drought Tolerance in Wheat

Genetic diversity is invaluable in developing climate-smart and drought-adapted wheat varieties. The aim of this study was to determine the extent of genetic variation present in wheat germplasm collections for biomass allocation and drought tolerance based on complementary phenotypic and root attributes and high-density single nucleotide polymorphism (SNP) markers to select breeding parents. A total of 97 bread wheat (Triticum aestivum L.) genotypes were evaluated in field and greenhouse trials under drought-stressed and non-stressed conditions. The molecular variance analysis showed that the intrapopulation variance was very high at 99%, with a small minimal inter-population variance (1%). The genetic distance, polymorphic information content and expected heterozygosity were 0.20–0.88, 0.24–1.00 and 0.29–0.58, respectively. The cluster analysis based on SNP data showed that 44% and 28% of the assessed genotypes maintained their genetic groups when compared to hierarchical clusters under drought-stressed and non-stressed phenotypic data, respectively. The joint analysis using genotypic and phenotypic data resolved three heterotic groups and allowed the selection of genotypes BW140, BW152, BW157, BW162, LM30, LM47, LM48, LM52, LM54 and LM70. The selected genotypes were the most genetically divergent with high root biomass and grain yield and are recommended for production or breeding.

Matching of Soil Phosphorus Distribution and Root Distribution in Cotton Field Based on Diffusive Gradients in Thin-Films (DGT)

ABSTRACT This study aimed to optimize the period of drip phosphorus (P) fertilization to increase P migration distance in soil and content in cotton, so as to achieve the coordinated above and belowground growth of cotton plants. A field experiment was conducted to study soil P in response to P application by drip irrigation during different periods of cotton cultivation using diffusive gradients in thin films (DGT) in situ. The root length density, biomass, P content and lint yield of cotton were investigated. Compared with broadcast P fertilization before plowing, drip P fertilization after sowing significantly increased DGT-P and root length density in the top 0–15 cm soil layer, and significantly increased the biomass P content and lint yield of cotton, but reduced the root/shoot ratio. In addition, drip P fertilization at bud stage could also increase the DGT-P and root length density in the top 0–10 cm soil layer compared with the broadcast P fertilization treatment. Our results indicate that drip P fertilization after sowing is an effective method to expand the vertical migration of P in soil, increase the length, density, and P content of shoot, and improve the growth of cotton.

Mucuna pruriens, Crotalaria juncea, and chickpea (Cicer arietinum) have the potential for improving productivity of banana‐based systems in Eastern Democratic Republic of Congo

AbstractIntercropping banana and shorter annual crops in small holder systems is inevitable despite shade being a limitation. Current production is also limited to the wet seasons. Strategies to exploit the spaces under banana shade and drier seasons are crucial for optimal production of these systems. We determined the performance of two legume cover crops, Mucuna pruriens and Crotalaria juncea, and chickpea (Cicer arietinum), a grain legume, under different banana shade levels and over the wet and dry seasons in eastern Democratic Republic of Congo. Banana and legume monocrops served as controls. Shade reduced weed biomass and legume root nodulation, biomass, and grain yields. Chickpea root nodulation had a lower sensitivity to shade (3–9% reduction) compared with mucuna (30–60%) and crotalaria (31–71%). Legume biomass yield declines varied from 37–83%, 56–93%, and 80–98% for mucuna, crotalaria, and chickpea, respectively. Higher nodulation occurred in the rainy compared with the dry season. Biomass yield declines, albeit low occurred in the dry season for mucuna (15%) and crotalaria (30%). In contrast, chickpea biomass and grain yields increased by 394% and 4487%, respectively, in the dry season. A higher banana vegetative growth occurred in the intercropped plots. Land equivalent ratios of 1.15–1.34 under dense shading for mucuna and crotalaria and 1.10–1.62 for chickpea occurred irrespective of the seasons. These findings suggest that these cover crops and chickpea could be exploited to enhance biomass (for fodder, mulch, or manure) and grain yields under banana shade and over the drier seasons.

Infection by Moniliophthora perniciosa reprograms tomato Micro-Tom physiology, establishes a sink, and increases secondary cell wall synthesis.

Witches' broom disease of cacao is caused by the pathogenic fungus Moniliophthora perniciosa. By using tomato (Solanum lycopersicum) cultivar Micro-Tom (MT) as a model system, we investigated the physiological and metabolic consequences of M. perniciosa infection to determine whether symptoms result from sink establishment during infection. Infection of MT by M. perniciosa caused reductions in root biomass and fruit yield, a decrease in leaf gas exchange, and down-regulation of photosynthesis-related genes. The total leaf area and water potential decreased, while ABA levels, water conductance/conductivity, and ABA-related gene expression increased. Genes related to sugar metabolism and those involved in secondary cell wall deposition were up-regulated upon infection, and the concentrations of sugars, fumarate, and amino acids increased. 14C-glucose was mobilized towards infected MT stems, but not in inoculated stems of the MT line overexpressing CYTOKININ OXIDASE-2 (35S::AtCKX2), suggesting a role for cytokinin in establishing a sugar sink. The up-regulation of genes involved in cell wall deposition and phenylpropanoid metabolism in infected MT, but not in 35S::AtCKX2 plants, suggests establishment of a cytokinin-mediated sink that promotes tissue overgrowth with an increase in lignin. Possibly, M. perniciosa could benefit from the accumulation of secondary cell walls during its saprotrophic phase of infection.

Intermittent flooding lowers the impact of elevated atmospheric CO2 on CH4 emissions from rice paddies

Atmospheric CO2 concentrations and water management practices both affect greenhouse gas (GHG) emissions from rice paddies, but interactive effects between these two factors are still unknown. Here, we show the first study to compare the impact of elevated atmospheric CO2 (eCO2) on GHG emissions under continuously flooded irrigation (CF) and under intermittently flooded (IF) conditions. Elevated CO2 stimulated CH4 emissions under CF by 50% in a field experiment and by 46% in a pot experiment, but it had no effect under IF in both experiments. Elevated CO2 had no effect on N2O emissions in either the field or pot experiment. Rice root biomass, aboveground biomass and grain yield increased with eCO2, but were not affected by water management. Elevated CO2 only stimulated the abundance of methanogens under CF, suggesting that increased soil O2 availability with IF limited methanogenic activity under eCO2. Our findings suggest that estimates of CH4 emissions from global rice agriculture with eCO2 need to account for recent changes in water management.

Influence of compost Amendments on the germination and Growth performance of Zea mays L.

Maize is a highly consumed staple food in developing countries and the demand is predicted to double in the coming years. Therefore, there is a need to improve production through the use of compost amendments for sustainability. The aim of this study was to examine the effect of three compost amendments (lemon peels, vegetable waste, and cooked food waste) on the germination and growth of maize (Zea mays). The results showed that the application of 17% (116 t/ha) of vegetable waste or lemon peel composts supported maximum maize growth. However, vegetable waste compost had the highest potassium content, which supported maximum root growth and biomass yield. Although the addition of 17% cooked food waste compost resulted in excess nitrogen supply, reducing its application to 7% (50t/ha) supplied the required level for maize germination.