Plant mediated methane efflux from a boreal peatland complex

Purpose Aerenchymous plants are an important control for methane efflux from peatlands to the atmosphere, providing a bypass from the anoxic peat and avoiding oxidation in the oxic peat. We aimed to quantify the drivers of aerenchymous peatland species methane transport and the importance of this process for ecosystem-scale methane efflux. Methods We measured seasonal and interspecies variation in methane transport rate per gram of plant dry mass at a boreal fen and bog, which were upscaled to ecosystem-scale plant methane transport. Results Methane transport rate was better explained by plant species, leaf greenness and area than by environmental variables. Leaves appeared to transport methane even after senescence. Contrary to our expectations, both methane transport rate and the proportion of plant transport were lower in the fen (with greater sedge cover) than in the bog site. At the fen and bog, average methane transport rate was 0.7 and 1.8 mg g−1 d−1, and the proportion of seasonally variable plant transport was 7–41% and 6–90%, respectively. Species-specific differences in methane transport rate were observed at the ecosystem-scale: Scheuchzeria palustris, which accounted for 16% of the aerenchymous leaf area in the fen and displayed the greatest methane transport rate, was responsible for 45% of the ecosystem-scale plant transport. Conclusion Our study showed that plant species influence the magnitude of ecosystem-scale methane emissions through their properties of methane transport. The identification and quantification of these properties could be the pivotal next step in predicting plant methane transport in peatlands.

Metabolic Adjustment of Glycine max (L.) Merril in the Presence of Nitrate and Bradyrhizobium japonicum

Reactive oxygen species are generated during the processes of photosynthesis and nitrate reduction, which can compromise the integrity of biomolecules and membranes. During the vegetative phase of Fabaceae species, around half of translocated carbohydrate is used for nodule growth, while the other half returns to the aerial part with nitrogen incorporated. These sugars may be yet involved with membrane stabilization, signaling, and activation of important genetic pathways for plant development. Thus, the aim was to study the adjustments of the photosynthetic and antioxidant systems and the accumulation of carbohydrates and biomass in Glycine–Bradyrhizobium cultivated with nitrate (NO3−). Four treatments were evaluated in completely randomized blocks. Glycine–Bradyrhizobium was grown with 1.7 mM of NO3− (GB: 1.7 mM NO3−) and without NO3− (GB: 0 mM NO3−), and Glycine was grown with 1.7 mM of NO3− (G: 1.7 mM NO3−) and without NO3− (G: 0 mM NO3−). Glycine–Bradyrhizobium symbiosis contributes to photosynthetic metabolism and total sugars, reduces the action of antioxidant enzymes, and minimizes the use of nitrate in soybean cultivation.; Glycine–Bradyrhizobium with nitrate provided greater plant dry mass in the vegetative phase, along with increased enzymatic activity and reduced nodule mass.

Dissecting the Genotypic Variation of Growth Responses to Far-Red Radiation in Tomato

The recent development of light-emitting diodes (LEDs) and their application in modern horticulture stimulated studies demonstrating that additional far-red (FR) radiation (700–800 nm) increases plant dry mass. This effect of FR has been explained by improved photosynthesis and/or plant architecture. However, the genotypic variation in this response is largely unknown. Here, we aim to explore and explain the genotypic variation in growth responses to additional FR. We expected the genotypic variation in the responses of plant dry mass to additional FR. Further, we hypothesized that a significant improvement of both net assimilation rate (NAR) and leaf area ratio (LAR) is responsible for a strong dry mass increase under additional FR, while some genotypes respond only marginally or even negatively in NAR or LAR under FR, thus resulting in a weak FR effect on plant dry mass. To test these hypotheses, we grew 33 different tomato genotypes for 21 days with 0, 25, or 100 μmol m–2 s–1 of FR added to a common white + red LED background lighting of 150 μmol m–2 s–1. Genotypes responded similarly with respect to plant height, stem dry mass, and shoot:root ratio; i.e., they all increased with increasing FR. However, the response of total plant dry mass varied among genotypes. We categorized the genotypes into three groups (strongly, moderately, and weakly responding groups) based on their relative response in total plant dry mass to FR. Growth component analysis revealed that the strongly responding genotypes increased strongly in NAR rather than LAR. The weakly responding genotypes, however, showed a substantial increase in LAR but not NAR. The increase in LAR was due to the increase in specific leaf area. Leaf mass fraction, which is the other component of LAR, decreased with FR and did not differ between groups. In conclusion, tomato genotypes that increased strongly in NAR in response to FR were able to achieve a more substantial increase in dry mass than did other genotypes. This is the first study to explain the differences in growth responses of a large number of tomato genotypes toward FR in their light environment.

Forage yield, structural responses and chemical composition of spineless cactus Orelha de Elefante Mexicana in different water depths and irrigation frequencies

ABSTRACT: The objective was to evaluate the effects of water depths and irrigation frequencies on structural responses, forage yield and chemical composition of spineless cactus Orelha de Elefante Mexicana (OEM) (Opuntia stricta (Haw.) Haw), in adensed crop system. The experimental design was randomized blocks, in subdivided plots (3x4) with 4 replicates. The water depths were (100%, 75%, 50%, and 25% of ETc - crop evapotranspiration) and three water application frequencies (7; 14 and 28 days between irrigations). There was interaction for water use efficiency (WUE) and plant dry mass. Increasing water depths reduced WUE for all irrigation frequencies and plant dry mass was lower for 7 days compared to 14 and 28 days in 25% ETc. Greater water depths increased linearly the plant height and plant width. First and second order cladode length, second order cladode dry mass (kg), fresh mass yield (FMY) (kg ha-1) and dry mass yield (DMY) (kg ha-1) had a quadratic response with the increase in water depth. The FMY and DMY increased up to 77% and 75% ETc, respectively. Irrigation frequency (28 days) promoted greater first order cladode length and cladode dry mass compared to 7 days. Cladode thickness in plant and basal cladode thickness were greater for 7 days compared to 28 days and 14 and 28 days, respectively, without influence on FMY and DMY. Irrigation frequencies from 7 to 28 days promotes similar forage production and water depths up to 77% ETc favors the forage yield for spineless cactus Orelha de Elefante Mexicana receiving supplemental irrigation.

Root growth and anatomy of Typha domingensis Pers. related to phosphorus availability

Aim The capacity of macrophytes to colonize large areas is often referred to as dependent of the investment in root system and its capacity to uptake nutrients. This work aimed to evaluate the phosphorus (P) effects on the root growth and anatomy as well as its capacity to uptake this nutrient by the aquatic macrophyte Typha domingensis. Methods Plants were grown for 60 days in nutrient solution containing 0, 0.2, 0.4, 0.6 or 0.8 mM of phosphorus. At the end of the experiment, the root length and P root content as well as the root anatomy at the maturation and meristematic zones were evaluated. Results Higher P concentrations increased the uptake of this nutrient and plant dry mass. However, the root length was reduced by higher phosphorus levels. In addition, P increased the proportion of the root cap while reduced the proportion of the procambium at the meristematic zone. Higher phosphorus concentrations reduced the xylem vessel diameter and the proportion of the vascular cylinder at the maturation zone, whereas increased phloem proportion was observed under this condition. Furthermore, higher phosphorus levels reduced the endodermis and exodermis thickness as well as the aerenchyma proportion. Conclusions Therefore, the T. domingensis P requirement is fulfilled at 0.4 mM of this nutrient and hypertrophic conditions promote the development of unfavorable root anatomical traits and reduction of the root growth.

Kamafugite From the Alto Paranaíba Province as a Multi-nutrient Fertilizer

The study evaluated the potential agricultural use of kamafugite as a multi-nutrient fertilizer in the cultivation of Urochloa brizantha. Two experiments were carried out under greenhouse conditions, one using a Ferralsol and the other an Arenosol. The experimental design was a randomized block with four replicates, in a factorial scheme 4 × 2 + 2, comprising four doses of kamafugite (1667, 3334, 6668, and 13336 mg dm-3), two product forms (filler and powder), and two additional treatments, TSF + KCl and a control treatment without K2O and P2O5 application. The sources were incubated for 60 days on two soil types and, after the incubation period, Urochloa brizantha plants were grown and two consecutive cuts were performed. The kamafugite was efficient in increasing plant dry mass and the levels of P, K, Ca, and Mg accumulated in plants, mainly in the 2nd Urochloa brizantha crop. The granulometry filler was more efficient in the sandy soil and the form powder in the clayey soil. Kamafugite can be used as an alternative source of nutrients for the Urochloa brizantha crop, being a low-cost and a potential source to improve tropical soil fertility over time.

Fruit shape regulates susceptibility of tomato to blossom-end rot

Calcium (Ca2+) is a nutrient in tomato plants, of which deficiency usually causes several problems including a physiological disorder known as blossom-end rot (BER) in the fruit. The objective of this study was to evaluate and identify morphological and physiological characteristics related to the susceptibility of tomato varieties to BER. The varieties studied were ‘Amalia’, ‘IPA-6’, ‘M-82’, ‘Mara’, and ‘Nagcarlan’, presenting different fruit formats. Physiological parameters that negatively correlated with BER were plant water potential, leaf area, plant dry mass, relationship between proximal/distal Ca2+, K+ content in the proximal and distal portions of the fruit, and proximal Ca2+ content. Physiological parameters that positively correlated with BER were number of trichomes in the abaxial and adaxial leaf portions, leaf stomatal conductance, distal Ca2+ content bound to the cell wall, leaf transpiration, and fruit length. Our results showed that ‘Mara’ and ‘Nagcarlan’, ‘Amalia’ and ‘IPA-6’, and ‘M-82’ presented low, medium, and high susceptibility to BER, respectively. We also found that total fruit Ca2+ concentration, particularly in the distal fruit tissue, was not the only factor responsible for the development of BER; rather, the balance between factors that increase and decrease the susceptibility of each variety affected development of this disorder.

Preliminary Evaluation of Growth Response of Two Cowpea Accessions to Water Stress

Water deficit is one of the most important factors that affect plant growth and development. To assess the effect of water stress on growth of two cowpea accessions (i.e. UCC 321 and GH 4769), a field study was conducted at the experimental site of CSIR-Plant Genetic Resources Research Institute, Bunso, Eastern Region-Ghana during the minor season. The treatments comprised of non-watered and well-watered cowpea plants for thirty-two days. The experiment was a 2 x 2 factorial replicated three times in a randomised complete block design. Growth was determined by measuring plant height, number of leaves per plant and plant dry mass (i.e. leaf, stem, root and total plant). Water stress reduced plant height, number of leaves and plant dry mass. Dry-mass accumulation in above-ground plant organs was lower in non-watered plants than in the well-watered treatment. This indicated that irrigation was necessary to optimize cowpea production, and that a deficit in irrigation might affect plant growth as soil becomes dry.

Saflufenacil Dose-Response Curves Applied to Brazilian ‘Cerrado’ Soils

The objective of this study was to evaluate the phytotoxicity of saflufenacil in Brazilian Cerrado soils with contrasting properties. Experiments were performed in a factorial design. To quantify herbicide phytotoxicity, the bioassay technique was used and cucumber (Cucumis sativum) was selected as a test plant. A greater reduction of the dry mass was observed for bioindicator plants in comparison to others in the Typic Dystrophic Red Latosol. A rate of 11.76 g i.a. ha-1 was required to reach 50% reduction of the plant dry mass for this soil. Rates of 30.87; 44.10, and 119.56 g i.a. ha-1, respectively, are needed to achieve a 50% reduction of the plant dry mass in the Typic Acric Red Latosol, Typical Orthic Arenosols Quartzipsamment, and Washed Sand. The bioavailability of saflufenacil is affected by soil properties and therefore the soil type should be considered when deciding upon possible rates.

Effect of Spacing and Topping on the Performance of Hydroponically Grown Tomato Under Tropical Conditions

Production of tomato in the tropics especially in Ghana is beset with lots of setbacks thereby causing low yields per hectare. Greenhouse cultivation systems are promising yet yields of tropical tomato cultivars are hampered by adverse temperature conditions. In order to mitigate this, an experiment was conducted during the extreme summer temperature conditions in the greenhouse at Kashiwanoha Campus of Chiba University, Japan. The study was conducted between May 23, 2018 and September20, 2018. The low substrate volume production system of 500mL in closed recirculated hydroponics (sub-irrigation) method was employed. Three tropical tomato cultivars (Jaguar, Lebombo and Lindo) were evaluated for yields. Plants were spaced at 20cm (4.2 plants m-2) and 30cm (2.8 plants m-2). At 7 and 9WAT, plants were topped at 2nd and 4th nodes respectively. The 3x2x2 factorial in Randomised Complete Block design in three replications was adopted. Some parameter collected were; 1. Morphometrics such as plant height, girth, leaf number and chlorophyll content, days to 50% flowering and fruit set 2. Yield components and fruit quality such as fruit number, marketable yield, yield per area, yield per hectare, percent blossom end rot, fruit TSS, TA, TSS/TA ratio and 3. Dry matter partitioning at last harvest, 11WAT. Results showed that blossom end rot reduced the yields of Jaguar and Lindo almost by 50% while Lebombo recorded less than 1%. Lebombo produced significantly the highest plant dry mass of 125g of which 57.7% was converted to vegetative growth compared to the Jaguar. For Jaguar however, 53.7% of total plant dry mass was allocated to fruits. This in effect was translated to the highest yield of 93tons ha-1 year-1 for Jaguar plants that were pinched at 4th truss in high density planting of 4.2 plant m-2.