Dry Mass Production Research Articles

Improving zinc supply enhances cotton nutritional phosphorus efficiency

Phosphorus (P) and zinc (Zn) uptake and their physiological use in plants are interconnected and tightly controlled. However, the extent to which these nutrients contribute to plants nutritional homeostasis remains poorly understood, as well as there is conflicting information about the interaction of these two nutrients, requiring a better understanding of nutritional homeostasis in different cultivars of cotton plants. Thus, this study aimed to evaluate the effect of Zn supply on the efficiency of P uptake and use in different cotton (Gossypium hirsutum L.) cultivars (IMA 8001 WS; TMG 44B2RF; FM 966). Plants were grown in Hoagland nutrient solution containing different levels of P and Zn (low and adequate supply). Biomass and mineral nutrition were evaluated in plants receiving contrasting levels of P and Zn supply. A balanced P and Zn supply (4 mM P × 4 µM Zn) enabled the highest biomass accumulation, while an imbalanced supply of these nutrients reduced P and Zn accumulation in the shoots in all cultivars. The TMG and FM cultivars grown under low P (0.5 mM) supply showed higher dry mass production and efficiency of P use when cultivated with adequate Zn (4.0 µM) than with low Zn (0.5 µM). The IMA cultivar demonstrated no effect of Zn on efficiency of P use. However, Zn supply in cotton increased P uptake in all cultivars grown with an adequate P supply. These results suggest that agricultural management strategies should aim for balanced mineral nutrition by considering cultivars to optimize yields and resource-use efficiencies.

Produtividade e extração de nutrientes pelo capim paiaguás submetido a doses de nitrogênio em cultivo solteiro e consorciado com feijão guandu

ABSTRACT The objective of this work was to evaluate the productivity and extraction of macronutrients by Urochloa brizantha cv. BRS Paiaguás (Syn. Brachiaria brizantha cv. BRS Paiaguás) single and intercropped with pigeon pea (Cajanus cajan cv. BRS Mandarim), subjected to four doses of nitrogen applied in topdressing (0, 80, 160 and 240 kg ha-1). The experiment was carried out in São Luís de Montes Belos, GO, in soil classified as dystrophic red latosol, under Cerrado conditions. Plant height and dry mass of pigeon pea, plant height, number of tillers, dry mass, and macronutrient extraction by Paiaguás palisadegrass were evaluated. Higher mass production was observed in the pasture intercropped with the legume, requiring a lower amount of N. Based on the results exposed, the cultivation of Paiaguás palisadegrass reaches higher productivity when intercropped with a legume such as pigeon pea, in addition to providing greater efficiency in the use of nutrients such as N, P and K. Nitrogen fertilization has a negative influence on the production of dry mass and height of pigeon pea plants.

Hydroponic forage of corn and millet grown on different organic substrates

The objective of this study was to evaluate the production and nutritive value of the hydroponic forage of corn and pearl millet grown in different organic substrates. It was carried out in a completely randomized design in 2 x 3 factorial scheme with four replications. The grasses used were corn and pearl millet and sugarcane bagasse, chopped elephant grass and chopped Brachiaria grass as substrates. The harvest was carried out 15 days after sowing, with seed density of 2 kg/m², irrigated with water and commercial nutrient solution. The productive parameters and chemical composition of the hydroponic forage were evaluated. The use of sugarcane bagasse substrate resulted in a greater production of total dry mass for corn among the other treatments, which reflected in better efficiency in the production parameters. As for substrates composed of chopped grass, lower values ​​of neutral detergent fiber were identified in both corn and pearl millet. The substrates and grass species affect the evaluated parameters, in which the use of sugarcane bagasse resulted in greater total production of dry mass using corn. The substrates based on chopped grass reflected in biomass with reduced fiber content, high levels of digestible nutrients, in addition to high protein content.

Forage quality and physiological performance of mowed alfalfa (Medicago sativa L.) subjected to combined light quality and drought.

Alfalfa (Medicago sativa) can dwell in water-deficient habitats, where it is difficult to predict dry mass (DM) production and forage quality due to understory transmittance. Mowing is a recommended practice for alfalfa populations under drought, but its effect on forested land receives less attention. In a controlled indoor experiment, we found that drought better reduces shoot DM weight and crude fiber content (CFi) in blue light (33.7% red, 48.5% green, and 17.8% blue lights) than red light (71.7% red, 13.7% green, and 14.6% blue lights). Mowing decreases carbon (C) isotope signature (δ13C), CFi, and total C content in shoots but increases their accumulations in DM, nonstructural carbohydrates, and crude fat content (CFa). The results also demonstrated that mown alfalfa has higher starch content when exposed to green light (26.2% red, 56.4% green, and 17.4% blue lights) compared to the other two spectra. Multiple factorial regression indicated that higher soluble sugar content accounted for the increase of CFa and DM weight for CFi. Overall, mowing in blue-light-enriched understory stands is recommended and produces high-forage-quality alfalfa, which can be used as a lowered crude fiber component.

Results of estimating adaptability of sainfoin varieties in the south of the Rostov region

The purpose of the study was to estimate such adaptability parameters, as a linear regression coefficient, stress resistance, genetic flexibility and stability coefficient, according to the traits “green mass productivity” and “dry matter productivity”. The objects of the study were 6 sainfoin varieties developed by the ARC “Donskoy”. The variety ‘Zernogradsky 2’ was taken as the standard one. Sowing was carried out in the spring with the SSFC-7 seeder in its pure form, without a cover crop. A seeding rate was 5 million germinated seeds per 1 ha. The area of the plot was 20 m2, with fourfold repetition. The estimation according to the indicators of ecological adaptability was performed according to the S. A. Eberchart and W. A. Russel (1966) as presented by V. A. Zykina et al. (2011), calculation of stress resistance and genetic flexibility was established according to A.A. Goncharenko (2005). The results of the analysis of variance have shown a significant influence of factor B (conditions) both on the variability of productivity of green mass (79.12 %) and dry matter (75.38 %). All the studied sainfoin varieties according to the years and sowing significantly exceeded the indicators of the standard variety. The most productive of them, the new variety ‘Atamansky 20’, formed on average 30.9 t/ha of green mass and 8.3 t/ha of dry mass, with fluctuations over the years, respectively, 24.8–44.9 t/ha and 6.4 –12.1 t/ha. The sainfoin varieties differ in the response of green and dry mass productivity to changing environmental conditions. The varieties ‘Zernogradsky 2’, ‘Atamansky’ and ‘Atamansky 20’ demand to improve conditions when cultivated for green feed and hay (bi > 1), while the varieties ‘Veles’, ‘Sudar’ and ‘Shuravi’ respond less well to improved environmental conditions and are more adaptable (bi < 1). The varieties ‘Veles’, ‘Sudar’ and ‘Shuravi’ are highly resistant to stress, while the varieties Zernogradsky 2’, ‘Atamansky’ and ‘Atamansky 20’ have a narrower range of adaptive capabilities of stress resistance. A higher correspondence between a genotype and environmental factors and high genetic flexibility were found in the variety ‘Atamansky 20’.

Roles of Calcium Signaling in Gene Expression and Photosynthetic Acclimatization of Solanum lycopersicum Micro-Tom (MT) after Mechanical Damage.

A momentary increase in cytoplasmic Ca2+ generates an oscillation responsible for the activation of proteins, such as calmodulin and kinases, which interact with reactive oxygen species (ROS) for the transmission of a stress signal. This study investigated the influence of variations in calcium concentrations on plant defense signaling and photosynthetic acclimatization after mechanical damage. Solanum lycopersicum Micro-Tom was grown with 0, 2 and 4 mM Ca2+, with and without mechanical damage. The expression of stress genes was evaluated, along with levels of antioxidant enzymes, hydrogen peroxide, lipid peroxidation, histochemistry, photosynthesis and dry mass of organs. The ROS production generated by mechanical damage was further enhanced by calcium-free conditions due to the inactivation of the oxygen evolution complex, contributing to an increase in reactive species. The results indicated that ROS affected mechanical damage signaling because calcium-free plants exhibited high levels of H2O2 and enhanced expression of kinase and RBOH1 genes, necessary conditions for an efficient response to stress. We conclude that the plants without calcium supply recognized mechanical damage but did not survive. The highest expression of the RBOH1 gene and the accumulation of H2O2 in these plants signaled cell death. Plants grown in the presence of calcium showed higher expression of SlCaM2 and control of H2O2 concentration, thus overcoming the stress caused by mechanical damage, with photosynthetic acclimatization and without damage to dry mass production.

CARACTERIZAÇÃO AGRONÔMICA DE GENÓTIPOS DE BATATA-DOCE OBTIDOS POR MEIO DE POLICRUZAMENTOS

ABSTRACT The average national sweet potato yield of Brazil falls below the productive potential of the crop because of the cultivation of local and unimproved varieties. To improve this, more productive cultivars must be adopted along with adequate culture treatments. This study was conducted between January and May 2019 in Selvíria, Mato Grosso do Sul, Brazil, to characterize sweet potato genotypes obtained through crossbreeding. The experimental design consisted of randomized blocks containing 264 genotypes, the control (‘Beauregard’), and two replicates. Plant harvesting began 127 d after planting. After harvesting, the roots were washed and dried in a covered area ready for evaluation. The total, commercial, and non-commercial yield; total, commercial, and non-commercial root number; root dry matter content; and dry matter productivity were evaluated. The genotypes CERAT16-20, CERAT31-1, and CERAT21-2 are promising in terms of root production for household consumption because of their high productivity of commercial roots. In contrast, genotypes CERAT16-20, CERAT31-1, CERAT25-17, CERAT25-12, CERAT21-2, CERAT29-26, CERAT34- 4, CERAT31-11, and CERAT24-8 are promising for industry because of the high production of dry mass per hectare. The main components, total number of commercial roots, production of non-commercial roots, mass of commercial roots, total production of dry mass of roots, mass of roots, and total production of roots have a low contribution to the discrimination of the genotypes; therefore, their analysis can be discarded in future studies, under the same soil and climate conditions, thus reducing workload, expense, and time.

EVALUATION OF ADVANCED TOMATO MUTANTS BASED ON GROWTH, YIELD ATTRIBUTES AND YIELD

Field experiment was conducted during November 2009 to March 2010, to investigate growth and yield attributes of advanced tomato mutants (TM-110 and TM-219) along with three cultivars (BARI tomato-3, BARI tomato-14 and BINA tomato-5) following randomized complete block design with three replications. There were significant genotypic differences in respect of morpho-physiological characters (plant height, branch and leaf area, total dry mass, absolute growth rate and relative growth rate), biochemical parameter (nitrate reductase), reproductive characters (number of effective and non-effective flower cluster, number of flowers and reproductive efficiency), phenological characters (days to flowering start, days to first harvest and harvesting duration), yield attributes and fruit yield. In general high yielding genotypes showed superior performance in plant height, branch number, leaf area, total dry mass production, absolute growth rate, nitrate reductase activity and fruit size compared to low yielding ones. Relative growth rate,chlorophyll, photosynthesis, reproductive characters and fruit number had no relationship with fruit yield in tomato. The variety BARI tomato-14 showed the highest fruit yield (77.7 t ha-1) due to its superiority in respect of morpho-physiological, biochemical and larger fruit sizes. In contrast, the mutant TM-110 and the variety BINA tomato-5 produced the lower fruit yield (average 51.2 t ha -1) due to poor performance in growth characters and smaller size of fruits. However, TM-110 matured 4-15 days earlier than the other mutant/varieties. Further, harvesting duration was higher in high yielding genotypes than low yielding ones. The highest harvesting duration was recorded in BARI tomato-14 (28 days) followed by BARI tomato-3 (26 days). This information may be implicated in future plant breeding programme.

Silicon modifies C:N:P stoichiometry and improves the physiological efficiency and dry matter mass production of sorghum grown under nutritional sufficiency

Silicon (Si) may be involved in the modification of C:N:P stoichiometry and in physiological processes, increasing sorghum growth and grain production. The objective was to evaluate the effect of Si supply on C:N:P:Si stoichiometry, physiological response, growth, and grain production of sorghum. The experiment was carried out in pots with four concentrations of Si: 0; 1.2; 2.4; and 3.6 mmol L−1 in a completely randomized design, with six replicates. Physiological attributes and dark green color index were measured and grain and biomass production were determined. Posteriorly, the plant material was ground to determine silicon (Si), carbon (C), nitrogen (N), and phosphorus (P) contents in order to analyze C:N:P:Si stoichiometry. C:Si and C:N ratios decreased at all Si concentrations applied (1.2, 2.4, and 3.6 mmol L−1) and in all plant parts studied, being lower at 3.6 mmol L−1. The lowest C:P ratios of leaves and roots were observed at 3.6 mmol L−1 Si and the lowest C:P ratio of stems was observed at 1.2 mmol L−1 Si. Si concentrations were not significant for the N:P ratio of leaves. The highest N:P ratio of stems was observed at 3.6 mmol L−1, while the lowest N:P ratio of roots was observed at 2.4 and 3.6 mmol L−1. Regardless of photosynthetic parameters, the application of 1.2 mmol L−1 Si enhanced photosynthetic rate. The application of 2.4 and 3.6 mmol L−1 enhanced stomatal conductance and dark green color index. The mass of 1000 grains was not influenced by Si applications, while Si applications at all concentrations studied (1.2, 2.4, and 3.6 mmol L−1) enhanced shoot and total dry matter, not affecting root dry matter and grain production. In conclusion, Si supply modifies C:N:P:Si stoichiometry and increases physiologic parameters, growth, development, and grain production in sorghum.

Energy potential of wood from clones of Eucalyptus and Corymbia in different spacings

This study aimed to determine the influence of spacing and different genetic materials of Eucalyptus and Corymbia on wood production for energy purposes. At 24 months, two Eucalyptus clones (C1 and C2) and two Corymbia clones (C3 and C4) implanted in three different spacings (3.0 × 3.0, 3.0 × 1.5, and 3.0 × 1.0 m) were evaluated, totaling 12 treatments. In each treatment, 4 trees were selected, and 5 disks were removed from each tree, which were used to determine the basic density, the higher calorific value and to quantify the elemental carbon in the wood. Based on these characteristics, it was possible to estimate the dry mass, the carbon mass, and the amount of energy per hectare. It was observed that there was an effect of spacing, clone and interaction for the basic density of wood, being observed in clone C3 (C. citriodora × C. torelliana) the highest values of this property. As for the higher calorific value and the carbon content, no significant effect was found. It was also verified that the production of dry mass, carbon mass, and the amount of energy available per hectare increased with the densification of the spacings for all clones studied. The highest values of the amount of energy per hectare, in the different spacings, were attributed to clones C2 and C3 (3.0 × 3.0 m), clone C3 (3.0 × 1.5 m), and clones C1 and C3 (3.0 × 1.0 m). The C3 clone (Corymbia hybrid) can be a good alternative for energy use, due to its wood quality and productivity similar, or even superior, to Eucalyptus clones already used for this purpose.

FOLIAR APPLICATION OF BIOSTIMULANT DOSES IN TWO PHENOLOGICAL STAGES IN COMMON BEAN CULTURE

Salinity is one of the environmental stresses that most affects plants' vital processes, especially germination. Brassinosteroids, including 24-epibrassinolide (EBL), have multiple actions in essential processes in plants. Thus, this research's objective was to evaluate the effects of EBL on tomato seeds' physiological conditioning on germination, growth, and production of dry seedling mass under salinity conditions. The experiment was carried out in a 2x5 factorial scheme, as follows: two concentrations of EBL (0 and 10-6 M) and five levels of salinity (0.5 control; 1.5; 3.0; 4.5 and 6.0 dS m-1), consisting of ten treatments, with four replications of 50 seeds. In isolation, the salt stress reduced the percentage of germination and germination speed index from four to 14 days, besides all the plants' growth traits. In turn, the EBL increased the percentage of germination, germination speed index, seedling length, and radicle dry matter. The application of 10-6 M of EBL in seed immersion no effect on the seed germination of IPA 6 tomato cultivar under salt stress but increases the root length and the dry matter of the seedlings.

Effect of organic and mineral fertilizers applications in pasture and no-tillage system on crop yield, fractions and contaminant potential of Cu and Zn

Organic wastes, fertilizers, organominerals, and minerals contain nutrients essential to crops and contribute to increase productivity. However their use can also lead to the accumulation of copper and zinc, which changes the distribution of their fractions and enhances the risk of toxicity to plants and the environment, thereby working against the sustainable development goals. However, the effect of manure applications on clayey soils and the effects of increasing Cu and Zn contents over the years on crop productivity remain unknown. This study aimed to evaluate the distribution and the potential for contamination of heavy metals in clayey soil with a history of the application of different types and amounts of fertilizers under Cynodon spp. grazing and no-tillage system for soybeans. In Experiment 1, Cynodon spp. were cultivated for hay production and submitted to applications of the following treatments: 0, 200, and 400 kg ha−1 of total-N in the form of pig slurry and urea. In experiment 2, the soybean was grown and subjected to the following treatments: control, pig slurry, commercial granulated solid organic fertilizer, organomineral fertilizer blended with granules, and mineral fertilizer blended with granules. The dose of each nutrient source was determined based on the soil analysis and the recommendations of the liming and fertilization manual. The experiments were conducted for four agricultural crops where soil samples were collected in the layer of 0.00–0.10 m layer and submitted to chemical fractionation of Cu and Zn. The use of pig manure increased the availability of Cu and Zn in the soil, causing an increase in the distribution of copper organic (40.73% and 57.64% for PS200 and PS400 treatments, respectively, in Experiment 1; 67.33% for PS treatment, in Experiment 2) and residual fractions (10.01% and 7.60% for PS200 and PS400 treatments, respectively, in Experiment 1; 9.80% for PS treatment, in Experiment 2), while zinc was predominant in clay-mineral (61.04% and 92.01% for PS200 and PS400 treatments, respectively, in experiment 1; 278.90% for PS treatment, in Experiment 2) and residual fractions (2.36% for PS200 treatment in experiment 1; 9.90% for PS treatment, in Experiment 2). Additionally, the use of swine manure increased the Cu and Zn contents in the exchangeable fraction, which may potentiate the toxicity to plants and increase the potential for contamination of subsoil water. However, the increased bioavailability of Cu and Zn did not caused a loss of crop productivity but instead increased dry mass production and crop yield.

Impact of Water Deficit Condition on Osmoregulation of the Brassica Species

Oilseed rape and mustard are mostly grown on conserved soil water in the Indian sub-continent. These crops generally suffer from water stress at reproductive period of development. Thus, to obtain higher stable yields of Brassica species under routine stress conditions, it is essential to identify and understand the interactions of different morpho-physiological traits responsible for drought resistance. To explicate interaction of traits related to biochemical, physio-morphological factors for sustaining drought resistance in Brassica species. Dry mass production and partition in a plant is important when increased yield are sought. A osmometer like plant cell which allows only selective solutes to pass through elastic membrane, cell wall and the thin layer of cytoplasm and a vacuole containing an aqueous solution. To express drought tolerance turgidity of cells maintained by osmotic adjustments.

Effects of the soil compaction on root growth of cover crops in the western Amazon

The intensification of agriculture has increased the traffic of heavy machines, which can cause soil compaction, becoming a limiting factor for plant growth and development. The aim of this work was to evaluate the effects of machine traffic on soil physical attributes, root growth and dry mass production of legumes and grasses cultivated as cover. The experiment was carried in Rolim de Moura (RO). The experimental design was randomized blocks, in a split-plot scheme, with three replications. The treatments in the plots consisted of four induced soil compaction states: 0, 1, 4, 7 passes of an agricultural tractor, and in the subplots four cover crops species: Crotalaria, Stylosanthes, Millet and Palisadegrass. After two days of intense rainfall, compaction was carried out by passing the wheelsets of a New Holland-TL85E agricultural tractor, with 88hp of power, 4x2 TDA, standard tires 7.5x16 and 18.4x34, with blowing pressure of 110 kPa and 124 kPa, with a total mass of 3.16 Mg. Density, microporosity, macroporosity and total porosity were evaluated, surface area, root length and diameter and dry mass were also evaluated. During the period of full flowering of each crop, trenches were opened in each subplot for root evaluation and deformed soil and shoot dry mass samples were collected for evaluation. Significant discrepancies were observed for the physical attributes evaluated, surface area, length and root diameter of grasses in relation to legumes. After a tractor pass, there is an increase in soil density, and reductions in macroporosity and total porosity.

THERMAL POTENTIAL OF THE MACROPHYTES Eichhornia crassipes (WATER HYACINTH) AND Pistia stratiotes (WATER LETTUCE)

Most of the world energy consumption comes from non-renewable sources, which are being depleted, so alternative sources are necessary. The purpose of this work was to evaluate the thermal energy potential of macrophytes Eichhornia crassipes (water hyacinth) and Pistia stratiotes (water lettuce). These macrophytes were evaluated by gravimetric analysis, growth temporal determination, immediate analysis, and determination of the calorific value, under Cfb climate, Campos Gerais Region of Paraná, Brazil. The upper calorific value of macrophytes ranged from 11,459 kJ kg-1 for water lettuce to 14,158 kJ kg-1 for water hyacinth, lower than the wood used (around 18,000 kJ kg 1). As for the dry mass productivity, the macrophytes varied from 6,889 kg ha-1 for water lettuce to 9,947 kg ha-1 for water hyacinth, also lower than the commonly used woods. The water hyacinth showed a higher potential than water lettuce. The values determined are lower, however, macrophytes are considered invasive in lakes have a high cost for maintenance, therefore, according to logistics, they can be an option as thermal energy.

Nitrogen metabolism of two tropical forage grass species: nitrogen availability × cultivars

The understanding about N metabolism in roots and/or shoots of forage grasses should help determine how some cultivars use N more efficiently. This study was designed to determine whether two Brachiaria brizantha cultivars and two Panicum maximum cultivars differ in their N metabolism. Two cultivars of Panicum maximum and two cultivars of Brachiaria brizantha were investigated under the supply of low and high nitrogen rates in a greenhouse experiment. Some characteristics such as dry mass production, total nitrogen, nitrate and ammonium concentrations and contents; nitrate reductase (NR) and glutamine synthetase (GS) activities; and total free amino acid concentrations in shoots and roots were measured. The results showed that Panicum cultivars showed higher NR activity and GS activity in diagnostic leaves (DL) than Brachiaria cultivars. Brachiaria cultivars showed the highest ammonium concentrations in roots at low N supply and Panicum cultivars at high N supply. The total amino acid concentrations in DL were highest in Panicum and root total amino acid concentrations were highest in Brachiaria. Panicum and Brachiaria cultivars differed in their nitrogen metabolism with varying N supply. The results indicate that at low nitrogen supply to the pasture, Brachiaria brizantha cultivar Piatã may be an option to use in less intensive production environments, instead of high dry mass production. For those pastures with high nitrogen availability, the cultivars Mombaça and Aruana of Panicum maximum were clearly superior to Piatã, which suggests priority in the selection of these cultivars to be used in more intensive production systems that apply more nitrogen

Impact of Si on C, N, and P stoichiometric homeostasis favors nutrition and stem dry mass accumulation in sugarcane cultivated in tropical soils with different water regimes.

Studies with silicon (Si) in sugarcane indicate a greater response in productivity in plants under stress, and the underlying mechanisms of Si in the crop are poorly reported. In this context, the benefits of Si in the crop’s stem production are expected to occur at the C:N:P stoichiometry level in plant tissues, benefiting plants with and without stress. However, the extension of this response may vary in different soils. Thus, this research aimed to evaluate if fertigation with Si modifies the C:N:P stoichiometry and if it can increase sugarcane’s nutritional efficiency and vegetative and productive parameters. Therefore, three experiments were installed using pre-sprouted seedlings to cultivate sugarcane in tropical soils belonging to the Quartzarenic Neosol, Eutrophic Red Latosol, and Dystrophic Red Latosol classes. The treatments comprised a 2 × 2 factorial scheme in each soil. The first factor was composed without water restriction (water retention = 70%; AWD) and with water restriction (water retention = 35%; PWD). The second factor presented Si concentrations (0 mM and 1.8 mM) arranged in randomized blocks with five replications. Fertigation with Si increases the Si and P concentration, the C and N efficiency, the C:N ratio, and the dry mass production. However, it decreases the C and N concentration and the C:P, C:Si, and N:P ratios in sugarcane leaves and stems regardless of the water regime adopted in the three tropical soils. Cluster and principal components analysis indicated that the intensity of the beneficial effects of Si fertigation on sugarcane plants varies depending on the cultivation soil and water conditions. We found that Si can be used in sugarcane with and without water stress. It changes the C:N:P homeostasis enough to improve the nutritional efficiency of C, P, N, and, consequently, the dry mass accumulation on the stems, with variation in the different cultivated soils.

TaMPK2B, a member of the MAPK family in T. aestivum, enhances plant low-Pi stress tolerance through modulating physiological processes associated with phosphorus starvation defensiveness

The mitogen-activated protein kinase (MAPK) cascades are present in plant species and modulate plant growth and stress responses. This study characterizes TaMPK2B, a MAPK family gene in T. aestivum that regulates plant adaptation to low-Pi stress. TaMPK2B harbors the conserved domains involving protein phosphorylation and protein-protein interaction. A yeast two-hybrid assay reveals an interaction between TaMPK2B and TaMPKK2 and between the latter and TaMPKKK;A, suggesting that all comprise a MAPK signaling cascade TaMPKKK;A-TaMPKK2-TaMPK2B. TaMPK2B expression levels were elevated in roots and leaves under a Pi starvation (PS) condition. Additionally, the induced TaMPK2B transcripts under PS in tissues were gradually restored following the Pi normal recovery condition. TaMPK2B overexpression conferred on plants improved PS adaptation; the tobacco lines with TaMPK2B overexpression enhanced the plant’s dry mass production, Pi uptake capacity, root system architecture (RSA) establishment, and ROS homeostasis relative to wild type under PS treatment. Moreover, the transcripts of genes in phosphate transporter (PT), PIN-FORMED, and antioxidant enzyme (AE) families, including NtPT3 and NtPT4, NtPIN9, and NtMnSOD1 and NtPOD1;7, were elevated in Pi-deprived lines overexpressing TaMPK2B. Transgene analyses validated their functions in regulating Pi uptake, RSA establishment, and AE activities of plants treated by PS. These results suggest that TaMPK2B-mediated plant PS adaptation is correlated with the modified transcription of distinct PT, PIN, and AE genes. Our investigation suggests that TaMPK2B is one of the crucial regulators in plant low-Pi adaptation by improving Pi uptake, RSA formation, and ROS homeostasis via transcriptionally regulating genes associated with the above physiological processes.

Productivity and grain size of coffee grown in different weed management systems

Intensive weed management is one of the most common practices in coffee cultivation areas. Consequently, some problems, such as soil degradation and the selection of herbicide resistant weed, have increased over time, but, if properly managed, weeds at coffee planting inter-rows can offer benefits of erosion control, nutrient recycling and crop sustainability. The aim of this study is to evaluate the effect of different weed management strategies on the productivity and coffee grain size, i.e., quality. The experiment is installed onto a resprouting Coffea arabica L. site, four years after it was established. Treatments are implanted at planting inter-row Urochloa ruziziensis, Pueraria phaseoloides, and spontaneous vegetation maintained by mowing, herbicides, and weeding. To measure dry matter accumulation, samples are taken with a 0.25 m2 square template at plots maintained by mowing and herbicide application. To evaluate the yield and granulometry, coffee fruits are harvested, processed and classified in a set of 14 sieves (grouped in flat or “moca” shapes). The methods of controlling herbicide and weeding show significance in relation to grain production, with the production of grains having a higher market value standing out, when compared with the other treatments. The accumulation of dry matter above soil, in treatments with herbicides and spontaneous vegetation positively influenced the early coffee productivity (2018), and with U. ruziziensis and spontaneous vegetation, positively influenced the productivity of late harvest (2019). The accumulation of dry matter on the soil tends to be positively linked to coffee productivity, especially in periods when there is a shortage of rain in the region under study; however, it cannot be stated that this influence relationship (causality) has a direct positive effect between dry matter mass production and productivity of future coffee plantations.

Brassinosteroid application increases tomato tolerance to salinity by changing the effects of stress on membrane integrity and gas exchange

Salinity is one of the environmental stresses that most cause losses in agricultural systems, including tomato production. Brassinosteroids, such as epibrassinolide (EBL), have multiple actions in essential processes in plants. Thus, the objective of this study was to evaluate the contributions of EBL to the growth, physiology, and production of tomato plants under salinity. The experiment was conducted in a factorial scheme, with five levels of water salinity (0.5 [the control], 1.5, 3.0, 4.5, and 6.0 dS m-1) and two concentrations of EBL (0 and 10-6 M). Salt stress reduced tomato growth, relative water content, membrane integrity, gas exchange, and fruit production. However, the exogenous application of EBL attenuated the adverse effects, partially improving these characteristics at all salinity levels. EBL reduced electrolyte leakage and increased membrane integrity and relative water content in control and stressed plants. Additionally, it increased the content of photosynthetic pigments, stomatal conductance, transpiration, and photosynthesis, which led to higher leaf dry mass production, fruit transverse diameter, and production per plant. Therefore, our results confirmed that foliar application of EBL improved the characteristics of stressed and non-stressed tomato plants.