Total Dry Mass Research Articles

Exogenous application of salicylic acid induces salinity tolerance in eggplant seedlings.

Under salt stress conditions, plant growth is reduced due to osmotic, nutritional and oxidative imbalance. However, salicylic acid acts in the mitigation of this abiotic stress by promoting an increase in growth, photosynthesis, nitrogen metabolism, synthesis of osmoregulators and antioxidant enzymes. In this context, the objective was to evaluate the effect of salicylic acid doses on the growth and physiological changes of eggplant seedlings under salt stress. The experiment was conducted in a greenhouse, where the treatments were distributed in randomized blocks using a central composite matrix Box with five levels of electrical conductivity of irrigation water (CEw) (0.50; 1.08; 2.50; 3.92 and 4.50 dS m-1), associated with five doses of salicylic acid (SA) (0.00; 0.22; 0.75; 1.28 and 1.50 mM), with four repetitions and each plot composed of three plants. At 40 days after sowing, plant height, stem diameter, number of leaves, leaf area, electrolyte leakage, relative water content, and total dry mass were determined. ECw and SA application influenced the growth and physiological changes of eggplant seedlings. Increasing the ECw reduced growth in the absence of SA. Membrane damage with the use of SA remained stable up to 3.9 dS m-1 of ECw. The relative water content independent of the CEw increased with 1.0 mM of SA. The use of SA at the concentration of 1.0 mM mitigated the deleterious effect of salinity on seedling growth up to 2.50 dS m-1 of ECw.

Regimes hídricos nas respostas morfofisiológicas e bioquímicas de Croton blanchetianus (Euphorbiaceae)

ABSTRACT Plant species occurring in the Caatinga biome, when subjected to different water fluctuations, may have their morphophysiological and metabolic performance altered. Depending on the level of stress, the production of quality seedlings is affected. Therefore, the objective of this study was to evaluate the responses to different water availability levels in the morphophysiological and biochemical development of Croton blanchetianus Baill. The experiment was carried out in a greenhouse, evaluating four water regimes: 25%, 50%, 75% and 100% of pot capacity, and conducted in a randomized block design, with a total 5 blocks. The variables analyzed were: branch height and branch diameter; leaf area, number of leaves, root volume; root dry mass, shoot dry mass, total dry mass and root/shoot ratio; relative water content, proline, total soluble proteins, malondialdehyde, hydrogen peroxide, and photo synthetic pigments (chlorophyll ɑ, chlorophyll b, and carotenoids). The species Croton blanchetianus Baill. shows drought tolerance mechanisms, demonstrated by the reductions of growth, leaf area, dry mass of seedlings and photo synthetic pigments. It adjusts osmotically with increments in the production of proline, which acts in osmoprotection when there is water deficit, and in the production of proteins under the lower and higher water regime. The species has full development of seedlings under water regimes between 75% and 80% and adapts to different water fluctuations.

Eficiência do sistema floating na produção de mudas de alface utilizando diferentes bandejas e concentrações de solução nutritiva

ABSTRACT The quality of seedlings is a determining factor to guarantee the greatest potential crop productivity. The aim of this study was to evaluate the quality of lettuce seedlings grown in floating system, in relation to cell volume and electrical conductivity of the nutrient solution. The experiment was carried out in a completely randomized design, in a 3 x 2 x 4 factorial scheme, with three replicates. Seedlings of three lettuce cultivars (Great Lakes 659, Elba and Creta) were produced in two types of trays (128 and 200 cells) and fertigated with nutrient solutions (four electrical conductivities of 1.0; 1.5; 2.0 and 2.5 dS/m). The variables evaluated were: height, number of leaves, length of the main root, stem diameter, leaf area, total dry mass and shoot dry mass/roots dry mass (MSPA/MSR) ratio. Great Lakes 659 showed more vigorous seedlings for most of the evaluated variables. The three cultivars produced higher quality seedlings when cultivated in trays with 128 cells, with the EC of the nutrient solution ranging from 1.8 to 2.0 dS/m.

Crescimento da linhaça oleaginosa descrito por modelo não linear logístico

ABSTRACT Knowledge on plant-atmosphere interactions is essential to understand the growth and development of agricultural crops. Thus, fitting growth curves is an important methodology to model plant growth and phenological stages. The study aimed to describe the growth of four oilseed flax materials cultivated in six agricultural years and with different sowing dates through the nonlinear logistic model. Nine experiments were carried out in Curitibanos, SC, Brazil, between 2014 and 2020, considering different sowing dates. Throughout the crop cycle, the number of leaves, number of secondary stems, plant height and total dry mass were measured. Nonlinear logistic model was fitted to the data, with the growth variables as the dependent variables and the accumulated thermal sum as the independent variable. Model fit and parameter estimation were obtained by ordinary least method, using a Gauss-Newton algorithm. The goodness of fit was measured by intrinsic and parametric nonlinearity, adjusted coefficient of determination, random standard error, standard deviation of fit, Akaike information criterion, and Bayesian information criterion. The performance of the nonlinear logistic model differed between the varieties and cultivars studied, in different years and sowing times. However, the use of the nonlinear logistic model improves inferences about the growth of oilseed flax, and the estimates of its parameters and critical points allow a biological and practical interpretation to assist in crop planning. Furthermore, the study suggests that the oilseed flax cycle is directly related to genotype × environment interactions, and when sown at later times, the materials tend to shorten their cycle.

Crescimento e atributos fisiológicos de mudas de mirtileiro inoculadas com fungos micorrízicosarbusculares

ABSTRACT: High-quality seedlings are one of the key factors in achieving high yield and precocity of blueberries. The inoculation of arbuscular mycorrhizal fungi (AMF) can enhance the development of seedlings in the nursery, ensuring more vigorous seedlings in a shorter time. This study evaluated the effect of inoculation of arbuscular mycorrhizal fungi on the development of ‘PowderBlue’blueberryseedlings. The treatments were arranged in a 4 x 2 factorial scheme, in which the first factor was the arbuscular mycorrhizal fungi Gigaspora rosea, Glomus clarum, G. rosea + G. clarum, and a control level without mycorrhizae, while the second factor consisted of usingindole-3-butyric acid(IBA) and a control level without IBA. Semi-hardwood cuttings were planted in pots containing sterilized soil and kept in a greenhouse for 660 days. The percentage of rooted cuttings, plant height, root system length, shoot dry mass, root dry mass, total dry mass, peroxidase (POD) and superoxide dismutase (SOD) enzyme activities, SPAD index, mycorrhizal efficiency and dependence, number of spores, and soil basal respiration were evaluated. Plants inoculated with G. clarum without IBA and inoculated with G. rosea with IBA showed higher dry matter and SOD and POD enzyme activities, but the use of IBA had a negative effect on the fungus. The inoculation of blueberry cuttings with G. clarummay help seedlingdevelopment, thus improving biometric and biochemical parameters. Furthermore, the plant regulator IBAwas essential in establishing the symbiosis between blueberry and the AMF G. rosea.

Impact of Soil Type and Placement of Xyway LFR Fungicide on Germination and Growth of Corn Seedlings Under a Controlled Setting

Xyway LFR was released for use in corn as an in-furrow fungicide during 2020. Producers have raised concerns of reduced emergence and growth in corn plantings. Here, I assessed the impact of Xyway LFR placement in relation to the seed for impacts on seedling emergence and growth in two contrasting soil types (sand versus topsoil) under controlled conditions. Soil was added to containers, and five corn seeds were placed in a row in a furrow within each container. Xyway LFR was applied in a band at labelled rates at 0 (directly on seed), 1.27, 2.54, or 5.08 cm away from the seed. Containers were maintained under a light bank, and germination over time, as well as seedling biomass, was assessed. Statistical analysis indicated that plants in topsoil had greater germination rates and dry masses than plants in sand. Total plant dry masses were reduced relative to controls when Xyway LFR was placed 0 cm from the seed. However, when placed 2.54 or 5.08 cm from the seed, this impact was not evident. Potential phytotoxic effects may be mitigated by placing the product in a band at least 2.54 cm from the seed furrow.

Produção de grãos verdes de feijão-caupi fertirrigado por gotejamento contínuo e pulsado

Abstract The objective of this work was to evaluate the production of green cowpea beans under conventional fertilization, different fertigation depths, and replacement of crop evapotranspiration (ETc) through continuous and pulse drip irrigation. The experimental design was a randomized complete block with 12 treatments distributed in a 5x2+2 factorial arrangement, with five ETc replacement irrigation depths (40, 60, 80, 100, and 120%), combined with two types of fertigation application (pulse and continuous) plus two additional treatments with pulse (control 1) and continuous (control 2) irrigation at 100% of ETc under conventional fertilization. The analyzed variables were: number of pods, number of grains, fresh and dry mass of pods and grains, and total shoot fresh and dry mass. Cowpea showed a better productive performance at the fertigation depths between 80 and 100% of ETc. Moreover, pulse fertigation promotes higher yields for all production variables analyzed. Regardless of the type of application (pulse or continuous), the productive variables show better results at the fertigation depths estimated for maximum physical efficiency than in the treatments with conventional fertilization and irrigation with a depth of 100% of ETc.

Evaluation of a Process to Separate Ensiled Corn Grain and Stover for Improved Utilization as a Biomass Feedstock

Highlights An experimental machine that combined air classification and mechanical screening was investigated to separate corn grain and stover. Important variables included stover:grain ratio, air velocity, and throughput. As much as 99.4% of the grain could be separated from the stover with less than 1% foreign matter in the grain. Abstract. Corn grain and chopped stover were stored anaerobically at 37% to 50% (w.b.) aggregate moisture content to create a unique biomass feedstock. However, after storage, the two fractions must be separated to accommodate different conversion pathways. In this work, a modified cleaning system from a grain combine harvester was evaluated to investigate its effectiveness in separating the grain from the stover. While this system has been purposefully built for this task, there is no previous literature on separating grain at high material other than grain (MOG) to grain ratios. Using this system, material was separated into four fractions: Grain, Tailings, Heavy MOG, and Light MOG. Subsamples were collected, oven dried, and then hydrodynamically separated to quantify the grain content in the four fractions. Several different configurations of air velocities, mass flow rate, material MOG: grain ratios, and sieve types and openings were investigated. Grain capture was defined as the fraction of the total grain dry mass collected in the grain and tailings fractions. In five experiments, the grain capture effectiveness varied from 89.2% to 99.4% on a dry basis. The dry basis foreign matter (FM) in the clean grain was 0.6% to 10.8%. The use of a modified combine cleaning system has the potential to be one step in a system to fractionate corn grain from stover (i.e., MOG) in a biorefinery that uses both starch and cellulose as biomass feedstocks. Keywords: Air classification, Anatomical fractionation, Cleaning shoe, Corn stover, Mechanical sieving.

Effect of biochar on biochemical properties of saline soil and growth of rice

To amend physical properties of coastal saline soil for rice production, six biochar treatments (0, 0.5, 1, 2, 4 and 6 kg biochar per m2 soil) were set up as CK, T1, T2, T3, T4 and T5, respectively and their effect on the biochemical properties of coastal saline soil and rice growth characteristics were evaluated in a barrel planting experiment. The results showed that compared with CK (with no biochar added), the soil EC of T1 and T2-T5 was reduced by 11.5 %, but increased by 8.8–62.9 %, respectively. The available potassium and organic matter contents of T1-T5 increased ranging from 3.7-10.2 % to 8.0–46.8 %, respectively. With the increase of the biochar amount, the urease activity of soil in the 0–10 cm deep soil showed an increasing trend by 194.8–744.6 % with T1-T5, compared with that of the CK treatment. The activity of alkaline phosphatase in soil increased first and then decreased, and its increment with T1-T5 was between 28.2 and 64.8 % in comparison with that of CK. With more biochar added to soil, the leaf dry weight, root dry weight, total dry matter mass, total root length, single panicle quality and weight per 100 grains showed a trend of increase first and then decrease. The highest incremental values of all measurements were obtained with T1 by 21.8 %, 23.9 %, 13.8 %, 33.9 %, 30.8 % and 11.6 % respectively, compared with those with CK. However, adding biochar in soil demonstrated insignificant effect on the weight of single panicle, panicle length, stem thickness, tillers, setting rate, soil hydrolyzable nitrogen, available phosphorus content, rice protein, amylose, and taste quality among all treatments. In summary, the application of 0.5 kg m−2 biochar can improve the biochemical properties of saline soil and therefore increase rice yield.

Cost estimation for launch vehicle families considering uncertain market scenarios

When optimizing the staging of a launch vehicle, usually a reference mission with a fixed payload mass is used to determine the specific launch cost (or a surrogate thereof, e.g. total mass or dry mass). While this approach neglects suboptimal loading, it delivers sufficiently good results for the evaluation of an individual launcher if the design mission is well known. However, this approach does not capture the full range of payloads that a launch vehicle is expected to launch during its operational lifetime. In order to estimate the cost and subsequently optimize the staging of such launch vehicle families, a full launch scenario has to be considered. The cost of an individual launch vehicle loses importance and the deciding factor is the total cost associated with launching the specified scenario. However, estimates of the future market inevitably include large uncertainties. These uncertainties and their impact are ideally considered and quantified when assessing the specific recurring cost of a single launch vehicle. The consideration of a whole launch market scenario is especially relevant when evaluating a family of launch vehicles, an option currently being discussed for future European launchers. In this case, the distribution of the payloads onto the different members of the launch vehicle family has to be optimized in order to reach the lowest possible cost. Within this manuscript, a method that allows the determination of the recurring cost of such a launcher family based on a launch market scenario including uncertainties is proposed. Based on the launch numbers derived from the combinatorial optimization, parametric cost models for recurring and non-recurring cost are adapted and applied to three possible future launch vehicle families.

Corn plant dry mass accumulation considering the previous crop by non-linear models

Corn is the most produced cereal in the world, used both in human and animal nutrition. This study aimed to compare the fit of the Logistic, Gompertz, and von Bertalanffy non-linear models to data on the accumulation of total dry mass, dry mass of stems, leaves, and ears in corn plants grown with straw mulch from common bean, millet, and Brachiaria brizantha in relation to the days after plant emergence. The assumptions of normality, homoscedasticity, and independence of residuals were checked by Shapiro-Wilk, Breusch-Pagan, and Durbin-Watson tests, respectively. The models were adjusted by the least squares method using the Gauss-Newton algorithm in the R software. The quality of the fit was evaluated based on the values of the coefficient of determination (R2), the residual standard deviation (RSD), the Akaike Information Criterion (AIC), and Bates and Watts curvature measures. The Logistic model presented the best fit for the dry mass of stems and ears, and the Gompertz model for the dry mass of leaves and total dry mass, based on the quality evaluators used.

Evaluating the Productivity of Radish Fertilized with a Mixture of Hairy Woodrose (Merremia aegyptia L.) and Carnauba Straw (Copernicia prunifera)”

Aims: The use of spontaneous species present in agricultural areas is of utmost importance for farmers who cultivate in the agroecological system.
 Place of Study: The experiment was conducted from June to August 2023 at the Rafael Fernandes experimental farm, in the district of Alagoinha (5º03'37 "S, 37º23'50" W), northwest of Mossoró, State of Rio Grande do Norte, Brazil, with the aim of evaluating the In study the productivity of radish fertilized with a mixture of hairy woodrose (Merremia aegyptia L.) and carnauba straw (Copernicia prunifera).
 Study Design and Methodology: The treatments consisted of five amounts of a mixture of hairy woodrose with carnauba straw (0.0; 1.2; 2.4; 3.6 and 4.8 kg m-2 of area). The spacing used was 0.2 x 0.1 m, with a pit-1 plant. The total area of the plot was 1.1 x 0.6 m, corresponding to 0.66 m-2, with a useful area of 0.42 m-2, consisting of twenty plants.
 Agronomic characteristics of Radish (Raphanus sativus L.): Plant height; root diameter; productivity of the area plus root; root weight and total dry mass and root dry mass.
 Conclusion: The amount of 4.5 kg m-2 of the mixture of hairy woodrose plus carnauba straw was what promoted the greatest increase with a maximum value of 1626.66 g m-2 for the aerial part plus root characteristic. The use of a mixture of fertilizers of plant origin is promising for the development of radish in the Mossoró-RN region, Brazil.

Container volume and doses of maximum technical efficiency of controlled-release fertilizer on the morphological quality of Cordia alliodora seedlings in Roraima

The objective of this study was to determine the correlation between the morphological characteristics of Cordia alliodora seedlings produced as a function of container volume and controlled-release fertilizer (CRF) doses under nursery conditions in Northern Amazon. The experimental design was a 2 x 6 factorial scheme, corresponding to two container volumes (1.8 and 2.2 L) and six doses of Forth Cote® (0, 1, 2, 4, 8, and 12 g L-1 in medium sand), with five replicates. The evaluations were: height (H), stem diameter (SD), shoot dry mass (SDM), root dry mass (RDM), total dry mass, increment in stem diameter (ΔSD) and increment in height (ΔH) obtained from the data collected every fifteen days, from transplanting, encompassing the period of plant growth until the end of the experiment (three months), in addition to Dickson quality index (DQI). Container volume of 2.2 L is suitable for the formation of good-quality Cordia alliodora seedlings at 90 days after transplanting. Controlled-release fertilizer doses from 8.0 g L-1 are not indicated to obtain seedlings of this species in the northern region of Brazil, with quality, regardless of the container volume.

Protein biomarkers for root length and root dry mass on chromosomes 4A and 7A in wheat

Improving the wheat (Triticum aestivum L.) root system is important for enhancing grain yield and climate resilience. Total root length (RL) and root dry mass (RM) significantly contribute to water and nutrient acquisition directly impacting grain yield and stress tolerance. This study used label-free quantitative proteomics to identify proteins associated with RL and RM in wheat near-isogenic lines (NILs). NIL pair 6 had 113 and NIL pair 9 had 30 differentially abundant proteins (DAPs). Three of identified DAPs located within the targeted genomic regions (GRs) of NIL pairs 6 (qDT.4A.1) and 9 (QHtscc.ksu-7A), showed consistent gene expressions at the protein and mRNA transcription (qRT-PCR) levels for asparagine synthetase (TraesCS4A02G109900), signal recognition particle 19 kDa protein (TraesCS7A02G333600) and 3,4-dihydroxy-2-butanone 4-phosphate synthase (TraesCS7A02G415600). This study discovered, for the first time, the involvement of these proteins as candidate biomarkers for increased RL and RM in wheat. However, further functional validation is required to ascertain their practical applicability in wheat root breeding. Significance of the studyClimate change has impacted global demand for wheat (Triticum aestivum L.). Root traits such as total root length (RL) and root dry mass (RM) are crucial for water and nutrient uptake and tolerance to abiotic stresses such as drought, salinity, and nutrient imbalance in wheat. Improving RL and RM could significantly enhance wheat grain yield and climate resilience. However, breeding for these traits has been limited by lack of appropriate root phenotyping methods, advanced genotypes, and the complex nature of the wheat genome. In this study, we used a semi-hydroponic root phenotyping system to collect accurate root data, near-isogenic lines (NILs; isolines with similar genetic backgrounds but contrasting target genomic regions (GRs)) and label-free quantitative proteomics to explore the molecular mechanisms underlying high RL and RM in wheat. We identified differentially abundant proteins (DAPs) and their molecular pathways in NIL pairs 6 (GR: qDT.4A.1) and 9 (GR: QHtscc.ksu-7A), providing a foundation for further molecular investigations. Furthermore, we identified three DAPs within the target GRs of the NIL pairs with differential expression at the transcript level, as confirmed by qRT-PCR analysis which could serve as candidate protein biomarkers for RL and RM improvement.

Fertilização com zinco melhora o crescimento e desempenho fotossintético de mudas de coqueiro anão verde

ABSTRACT Zinc is an essential micronutrient for plant metabolism and has been studied in several crops of economic interest. However, there is no evidence of its use in coconut crops. The objective of this study was to evaluate the influence of foliar zinc fertilization with doses of zinc on dwarf green coconut seedlings based on their nutritional status, growth attributes, and gas exchange. The experimental design consisted of randomized blocks, and the treatments consisted of different zinc doses (0, 5, 10, 15, 20, and 25 g per plant) with five replicates. Seedlings were positively influenced by zinc dose, mainly in terms of growth variables and gas exchange. Zinc fertilization reduced iron and manganese content and increased zinc concentrations in the leaf tissue. Zinc fertilization promoted an increase in leaf area, height, shoot dry mass, and total dry mass. Furthermore, zinc fertilization improved photosynthesis, transpiration, stomatal conductance, internal CO2 concentration, instantaneous water use efficiency, and intrinsic water use efficiency. The improvement in these growth indices and gas exchange, in most variables, was up to an estimated dose of approximately 16 g of zinc per plant and decreased with increasing doses.

Influence of herbicides and water stress levels on the initial establishment of Amaranthus deflexus

The objective was to evaluate the influence of water deficit on the growth and development of Amaranthus deflexus L. after the application of herbicides with different mechanisms of action. The experimental design used was completely randomized with a double factorial arrangement and split plots over time. Analysis of variance was performed using the mixed model methodology. For total dry mass, plant height, stem diameter, relative water content and chlorophyll content, weeds were subjected to three factors: products (water, glyphosate, diuron, nicosulfuron and 2.4-D), and water conditions (100, 60 and 30% of the tray capacity), applied in different times after the application of the product (0, 2, 4, 6 and 8 days) nested in the subplots. To evaluate the phytotoxicity scale, analyses were carried out from the second to the eighth day after herbicide application. At the end of the trial, there was a reduction in the magnitude of quantitative plant growth traits of A. deflexus L. due to the application of herbicides associated with water stress conditions. For the random variation resulting from the nested effect of time in the subplots, a decreasing trend was observed for the characters plant height, stem diameter, total dry mass, total chlorophyll content and relative water content, as well as an increase in plant phytotoxicity weeds until the eighth day after herbicide application, with an increase in the length of the evaluation subintervals.

Kinetic and stoichiometric parameters in the fed-batch bioreactor production of poly(3-hydroxybutyrate) by Bacillus megaterium using different carbon sources.

This study investigates the effects of different strategies on poly(3-hydroxybutyrate)-P(3HB) production in a fed-batch bioreactor by Bacillus megaterium using candy industry effluent (CIE), sucrose, and rice parboiled water (RPW) as carbon sources. In biosynthesis, kinetic and stoichiometric parameters of substrate conversion into products and/or cells, productivity, instantaneous, and specific conversion rates were evaluated. The maximum concentration of P(3HB) was 4.00g.L-1 (77% of the total dry mass) in 42h of cultivation in minimal medium/RPW added with a carbon source based on CIE, demonstrating that the fed-batch provided an increase of approximately 22% in the polymer concentration and 32% in the overall productivity in relation to medium based on commercial sucrose. Fed-batch cultivation also had the advantage of avoiding the extra time required for inoculum preparation and sterilization of the bioreactor during the batch, which thereby increased the overall industrial importance of the process. Effluents from the candy, confectionery, and/or rice parboiling industries can be used as alternative substrates for P(3HB) production at a low cost.

Growth, Dry Mass and Organics Solutes Accumulation in Cnidoscollus phyllacanthus (M. Arg) Pax & Hoffm.) Seedlings Under Salinity

Theoretical framework: The areas affected by salinity have increased in recent years, becoming a limiting factor for plants, negatively interfering with their growth and development. As a result of these effects, knowing species that tolerate this adverse salinity condition is fundamental, both from an environmental aspect and from a scientific point of view. Objective: This research aimed to verify the effects of salinity on the growth and accumulation of organic solutes of Cnidoscolus quercifolius seedlings. Method: The treatments consisted of five levels of NaCl (0, 50, 100, 200 and 400 mM), distributed in entirely randomized design, with four replications. The seedlings grew in ‘Leonard’ pots, containing washed sand and nutrient solution, kept under saline conditions for 60 days. The parameters analyzed were height; stem diameter; roots, stem, leaves, shoot, and total dry mass; and amino acids, proteins and total soluble sugars content. Results and discussion: Salinity reduced linearly all parameters evaluated, especially at the highest levels of salt in the medium, indicating that the C. quercifolius seedlings were intolerant to the imposed salinity, not being able to adjust osmotically. Research implications: Possibility of revegetation of areas with saline soil problems, reintegrating them into the production system. Originality/value: To know the forest species capable of surviving in areas affected by salinization, enabling the adoption of recovery techniques and practices.

Appropriate water and fertilizer supply can increase yield by promoting growth while ensuring the soil ecological environment in melon production

Water and fertilizer management in sustainable agricultural development needs to balance crop yield, quality, and soil ecological environment. Therefore, we conducted trials with nine treatments over two growing seasons in 2020 and 2021. The treatments included the three irrigation levels W1 (75% Ep), W2 (100% Ep), and W3 (125% Ep) and the three fertilization levels F1 (758.44 kg/hm2), F2 (948.05 kg/hm2), and F3 (1137.66 kg/hm2) with a N/P/K ratio of 2:1:3. The net photosynthetic rate (Pn) gradually decreased with the plant growing period, and was significantly (*) affected by fertilization at the flowering and fruiting stages. The chlorophyll content increased by 43.75% from the vine to flowering and fruiting stages and decreased by 12.50% in the mature stage, reaching a maximum following W1 application. W2F2 was the most effective in promoting total dry mass (TDM) during the vine and mature stages. Irrigation, fertilization and the interaction exerted a highly significant effect on the fruit quality and yield. Soluble solids performed best under W1F1, while free amino acid reached a maximum under W3F2. Moreover, water use efficiency increased with the fertilization amount, and was maximized in W1F3. At the same fertilizer level, soil nitrate N and available P content exhibited an increasing then decreasing trend with the increasing irrigation amount, while soil available K content increased with irrigation at all growth stages. Structural equation models of yield and quality formation were then established based on the co-occurrence analysis. Pn indirectly regulated the melon growth by TDM (0.87) (***), while growth was identified as the most important direct factor affecting the yield and quality of melon. Furthermore, soil residues indirectly affected yield and quality composition through efficiency. This study indicates that the sustainable practices for water and fertilizer management are essential to improve melon yield and quality in arid and semi-arid regions, and contribute to reducing the risk of soil contamination from agricultural production.

AVALIAÇÃO DE PARÂMETROS RELACIONADOS A FIXAÇÃO BIOLÓGICA DE NITROGÊNIO EM SOJA cv. TMG 2165 IPRO PRÉ-COINOCULADA EM DIFERENTES MOMENTOS ANTES DA SEMEADURA

The objective was to evaluate parameters of biological nitrogen fixation in soybean subjected to different treatments: T1 - control without the use of commercial inoculant; T2 - chemical nitrogen fertilization; T3 - commercial inoculant based Bradyrhizobium applied to the seeds on the sowing day; use of commercial inoculant containing Bradyrhizobium and Azospirillum bacteria applied at 0, 7 and 15 days before sowing (DBS), treatments T4, T5 e T6, respectively. In R2, the following parameters were evaluated: number of nodules and dry mass in the main root, secondary roots and total; shoot and total dry mass and nitrogen content in the soot (NCS). In R8, the accumulated nitrogen content in the grains (NCG) was measured. From the results obtained, it can be noted that for the nodulation parameters (nodular number and dry mass) the treatments that stood out were related to co-inoculation (T4, T5 e T6) without statistical difference regarding the period of application of the inoculant. With regard to NCS, there was a greater increase in treatments T4 and T2, which did not differ from each other and presented mean values of 33.84 and 33.23 kg ha-1, respectively. For NCG, T4 stood out with 58.43 kg ha-1, despite having statistical similarity to treatments that used the same inoculant applied to 7 (T5) and (T6) DBS, as well as T2 and T3. It can be concluded that the parameters to biological nitrogen fixation did not suffer a negative influence due to the application of early co-inoculation up to 15 days before soybean sowing.