scholarly journals Physiological Responses of Cowpea (Vigna unguiculata) Under Irrigation With Saline Water and Biostimulant Treatment

2018 ◽  
Vol 10 (12) ◽  
pp. 24
Author(s):  
Leonardo Vieira de Sousa ◽  
Rayanne Maria Paula Ribeiro ◽  
Manoel Galdino dos Santos ◽  
Fernando Sarmento de Oliveira ◽  
Hugo Ferreira ◽  
...  
Keyword(s):  
Vigna Unguiculata ◽  
Saline Water ◽  
Net Photosynthesis ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Saline Stress ◽  
Stress Effect ◽  
Negative Effects ◽  
Shoot Height ◽  
Cowpea Cultivars

Cowpea (Vigna unguiculata) is one of the world’s main crops, and it is a fundamental source of protein for semiarid regions population. In these regions, the use of high salts concentration water in irrigation systems is one of the major factors that contributes to reduced cowpea yield. One way to alleviate the negative effects of salinity is through the biostimulants application, which is a product that has beneficial substances to the plants metabolism. The aim of this study was to evaluate the application of biostimulant in cowpea cultivars under irrigation with saline water. The study was carried out in the Agrarian Sciences Center, of the Department of Agronomic and Forest Sciences of the Federal Rural University of the Semi-Arid, in the city of Mossoró, RN. The experimental design was completely randomized, with four replications. The treatments were arranged in 5 × 2 × 2 factorial scheme, with five doses of biostimulant (0, 15, 30, 45 and 60 mL L-1), two electrical conductivities of the irrigation water (0.5 and 5.0 dS m-1), and two cowpea cultivars (IPA-206 and BRS Guariba). The evaluated characteristics were: chlorophyll content index, stomatal conductance, net photosynthesis, internal CO2 concentration, transpiration rate, shoot height, stem diameter and shoot dry mass. The biostimulant application was not efficient in attenuating the salinity stress effect on the development of cowpea cultivars. The higher biostimulant concentrations along with the use of saline water increased the negative effects of salinity on the cowpea plants physiology. There was no difference between the cultivars regarding the tolerance to saline stress and the application of biostimulant.

scholarly journals Plant development, gas exchanges and pigments of Mesosphaerum suaveolens submitted to osmoconditioning and saline stress

2020 ◽  
Vol 80 (1) ◽  
Author(s):  
Francisco Romário Andrade Figueiredo ◽  
Jackson Silva Nóbrega ◽  
Reynaldo Teodoro de Fátima ◽  
Toshik Iarley da Silva ◽  
Rodrigo Garcia da Silva Nascimento ◽  
...  
Keyword(s):  
Irrigation Water ◽  
Saline Water ◽  
Block Design ◽  
Statistical Design ◽  
Saline Stress ◽  
Negative Effects ◽  
Gas Exchanges ◽  
Chlorophyll Pigments ◽  
Randomized Block Design ◽  
Dry Biomass

Salinity is one of the main plant abiotic stresses which affects the establishment and development crops. Hence, the search for technologies that minimize the damage caused by salinity is essential. The aim of the present work was to evaluate the effect of salinity stress and osmotic conditioning of seeds on the biomass, gas exchanges and chlorophyll pigments in Mesosphaerum suaveolens (L.) Kuntze. The statistical design adopted was a randomized block design, combined according to the Central Composite Design, referring to electrical conductivities of irrigation water and osmotic potentials, with minimum (- α) and maximum (α) values of 0.5 and 10.0 dS m-1 and 0.0 and -1.0 MPa, respectively, totaling nine combinations. The characteristics of dry biomass, gas exchange and chlorophyll indices were evaluated at 45 days after irrigation with saline water started. The salinity of irrigation water severely affected the dry biomass and the gas exchanges of M. suaveolens. Irrigation water of electrical conductivity above 3.2 dS m-1 caused reductions in chlorophyll a, b and total contents in M. suaveolens plants. Seed osmoconditioning did not attenuate the negative effects of saline stress on M. suaveolens plants.

scholarly journals IRRIGAÇÃO COM ÁGUA SALINA E USO DE SUBSTRATOS NA CULTURA DO FEIJÃO-CAUPI

Nativa ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 86-91
Author(s):  
Bruno Eduardo Lopes Sousa ◽  
Geocleber Gomes de Sousa ◽  
Andreza de Melo Mendonça ◽  
Max Ferreira dos Santos ◽  
Francisco Barroso da Silva Junior ◽  
...  
Keyword(s):  
Rice Husk ◽  
Vigna Unguiculata ◽  
Saline Water ◽  
Saline Stress ◽  
Initial Growth ◽  
Mineral Fertilization ◽  
High Salinity Water ◽  
Salinity Water ◽  
Number Of Leaves ◽  
Bean Crop

Objetivou-se avaliar a interação entre diferentes níveis salinos e substratos sob o crescimento inicial, o acúmulo de biomassa e as trocas gasosas da cultura do feijão-caupi. O experimento foi conduzido na área experimental da Universidade Federal do Ceará, Fortaleza, Ceará. O delineamento utilizado foi inteiramente casualizado em esquema fatorial (5 x 2), com quatro repetições. Os tratamentos foram constituídos por substratos inseridos ao solo (T1- biocarvão + solo na proporção 1:1; T2- solo (testemunha); T3- adubação mineral; T4- casca de arroz carbonizada + carnaúba + solo na proporção 2:1:1 e S5- casca de arroz carbonizada + solo na proporção 1:1), e duas águas de irrigação (1,0 e 4,0 dS m-1). Aos 40 dias após a semeadura (DAS) foram avaliados: número de folhas (NF), altura de planta (AP), diâmetro do caule (DC), área foliar (AF), massa seca da parte aérea (MSPA) e total (MST), fotossíntese (A), transpiração (E) e condutância estomática (gs). A água de alta salinidade afetou negativamente a AP, DC, MSPA e a gs das plantas. Os tratamentos T4 e T5 promoveram maior NF e A quando combinado com água não salina. Os tratamentos T4 e T5 proporcionaram maiores valores de gs e E. Palavras-chave: Vigna unguiculata L. Walp; salinidade; adubação.   Influence of saline stress and fertilizers on caupi bean crop   ABSTRACT: The objective was to evaluate the effects of salt stress on the initial growth, on the accumulation of biomass and on the gas exchange of the cowpea culture submitted to different substrates. The experiment was conducted in the experimental area of the Federal University of Ceará, Fortaleza, Ceará. The design used was completely randomized in a factorial scheme (5 x 2), with four replications. The treatments consisted of substrates inserted in the soil (T1- biochar + soil in the proportion 1: 1; T2- soil (control); T3- mineral fertilization; T4- carbonized rice husk + carnauba + soil in the proportion 2: 1: 1 and S5- carbonized rice husk + soil in a 1: 1 ratio), and two irrigation waters (1.0 and 4.0 dS m-1). At 40 days after sowing (DAS), the following were evaluated: number of leaves (NF), plant height (AP), stem diameter (DC), leaf area (AF), shoot dry matter (MSPA) and total (MST), photosynthesis (A), transpiration (E) and stomatal conductance (gs). High salinity water negatively affected AP, DC, MSPA and plant gas. The treatments T4 and T5 promoted greater NF and A when combined with non-saline water. The treatments T4 and T5 provided higher values of gs and E. Keywords: Vigna unguiculata L. Walp; salinity; fertilization.

scholarly journals Uso da subirrigação para imposição de estresse hídrico em sistema semi-contínuo para medição de CO2

2015 ◽  
Vol 21 (2) ◽  
pp. 235 ◽  
Author(s):  
Rhuanito Soranz Ferrarezi ◽  
Marc W. Van Iersel ◽  
Roberto Testezlaf
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Growth ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Co2 Exchange ◽  
Carbon Gain ◽  
Growth Responses ◽  
Shoot Height ◽  
Soil Moisture Sensors

The objectives of this work were to evaluate the effects of distinct moisture contents to trigger subirrigation on salvia photosynthesis and plant growth, and to verify the feasibility of subirrigation use in water stress imposition research in this crop. We evaluated two substrate volumetric water contents (VWC) as treatments (0.2 and 0.4 m3 m-3) to trigger subirrigation, with 4 replications. Each replication was composed of 10 plants. An automated semi-continuous multi-chamber crop CO2-exchange system was used, with capacitance soil moisture sensors for continuous moisture monitoring. Manual subirrigation with nutrient solution was performed when VWC dropped below the thresholds. In both treatments, the values of net photosynthesis, daily carbon gain and carbon use efficiency reduced over time, from 2 to 1.1 μmol s-1 from 2.2 to 1 μmol d-1 from 0.7 to 0.45 mol mol-1, respectively, in both soil moisture treatments. Total shoot dry mass (p=0.0129), shoot height in the tip of the highest flower (p<0.0001) and total leaf area (p=0.0007) were statistically higher at 0.4 m3 m-3 treatment. The subirrigation system was not efficient to impose water stress, due to excessive variation on VWC values after each irrigation event in both treatments. Higher soil moisture promoted positive plant growth responses in salvia cultivated by subirrigation.

scholarly journals Saline Water, Pit Coating and Calcium Fertilization on Chlorophyll, Fluorescence, Gas Exchange and Production in Passion Fruit

2019 ◽  
Vol 11 (2) ◽  
pp. 319
Author(s):  
Marlene A. F. Bezerra ◽  
Lourival F. Cavalcante ◽  
Francisco T. C. Bezerra ◽  
Aldeir R. Silva ◽  
Flaviano F. Oliveira ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Saline Water ◽  
Net Photosynthesis ◽  
Fruit Production ◽  
Passion Fruit ◽  
Plant Production ◽  
Water Salinity ◽  
Saline Stress ◽  
Leaf Chlorophyll ◽  
Calcium Fertilization

In plants sensitive to salinity, such as passion fruit, irrigation with saline water can cause physiological disturbances and reduce fruit production, necessitating the use of cultural practices that mitigate saline stress. The objective of this study was to evaluate the effects of water salinity, pit coating with high-strength polyethylene film, and calcium fertilization on the physiological and productive aspects of passion fruit ‘BRS Gigante Amarelo’. The treatments were arranged in split plot in the scheme 2WS × (2LP × 5DC), corresponding to water salinity (0.3 and 4.0 dS m-1) as the main plot, side coating of pits (without and with) doses of calcium (0; 30; 60; 90 and 120 kg ha-1). During the flowering phase, we evaluated leaf chlorophyll indices, fluorescence kinetics, and gas exchange. The increase in calcium doses up to 60 kg ha-1 increased leaf chlorophyll and quantum efficiency. The stomata did not restrict gas exchange, but salinity resulted in reduced net photosynthesis and plant production. The lateral coating of the pits intensified the reduction in salinity-promoted production, while calcium mitigated the effects of the salts. Entisol cultivated with passion fruit should not be irrigated with saline water of 4.0 dS m-1; lateral pit coating is not advised. In an Entisol with an initial calcium level of 1.92 cmolc dm-3, the recommended application dose is 60 kg ha-1 for passion fruit cultivation.

scholarly journals ESTRESSE SALINO E BIORREGULADOR VEGETAL EM FEIJÃO CAUPI

Irriga ◽  
2017 ◽  
Vol 22 (2) ◽  
pp. 314-329 ◽  
Author(s):  
Francisco De Assis de Oliveira ◽  
Mychelle Karla Teixeira de Oliveira ◽  
Luan Alves Lima ◽  
Rita De Cássia Alves ◽  
Lúcia Regina de Lima Régis ◽  
...  
Keyword(s):  
Vigna Unguiculata ◽  
Saline Water ◽  
Dry Mass ◽  
Commercial Plant ◽  
Severe Effect ◽  
Irrigation Water Salinity ◽  
Number Of Leaves ◽  
Four Levels ◽  
High Doses ◽  
E Mail

ESTRESSE SALINO E BIORREGULADOR VEGETAL EM FEIJÃO CAUPI  FRANCISCO DE ASSIS DE OLIVEIRA1; MYCHELLE KARLA TEIXEIRA DE OLIVEIRA1; LUAN ALVES LIMA1; RITA DE CÁSSIA ALVES1; LÚCIA REGINA DE LIMA RÉGIS1 E SANDY THOMAZ DOS SANTOS1 ¹ Departamento de Ciências Ambientais e Tecnológicas, UFERSA; Avenida Francisco Mota, 572, 59625-900, Bairro Costa e Silva, Mossoró, RN, Brasil, e-mail: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]  1 RESUMO O uso de água salina para a irrigação depende da adoção de tecnologias que reduzam o efeito da salinidade nas plantas. O presente trabalho foi desenvolvido em Universidade Federal Rural do Semi-Árido, em Mossoró, RN, com o objetivo de avaliar o efeito de bioestimulante sobre o feijão caupi irrigado com águas salinizadas. Utilizou-se o delineamento em blocos casualizado, em esquema fatorial 4 x 4, com quatro repetições, sendo quatro níveis de salinidade da água de irrigação (S1-0,5; S2-2,0; S3-3,5 e S4-5,0 dS m-1) e quatro doses de bioestimulante via pulverização foliar [B1-0 (água destilada), B2-5, B3-10 e B4-15 mL L-1], utilizando o fitorregulador comercial Stimulate®. Foram avaliadas as seguintes variáveis: número de folhas, área foliar, diâmetro do caule, massa seca de folhas, caule, vagens e massa seca total. Houve efeito significativo da interação entre os fatores em todas as variáveis analisadas. O uso de água com condutividade acima de 3,5 dS m-1 reduz o crescimento e a produção de grãos do feijão caupi, com efeito mais severo em doses elevadas de bioestimulante. O uso de bioestimulante favorece o crescimento e produção de biomassa, mas só é eficiente na ausência do estresse salino. O uso de Stimulate® não reduziu o efeito deletério da salinidade na cultura do feijão caupi, e quando utilizado em doses elevadas potencializou o efeito da salinidade. Palavras-chave: Vigna unguiculata L., salinidade, fitorreguladores  OLIVEIRA,F. A.; OLIVEIRA, M. K. T.; LIMA, L. A.; ALVES, R. C.; RÉGIS, L. R. L.; SANTOS, S. T.SALT STRESS AND PLANT BIOREGULATORS IN COWPEA CROP  2 ABSTRACT The use of saline water for irrigation depends on the adoption of technologies to reduce the effect of salinity in the plants. This study was conducted in Mossoró, RN/Brazil, in order to evaluate the effect of plant growth regulator application on cowpea irrigated with salted water. The study design was randomized blocks in a factorial 4 x 4, with four replications, with four levels of irrigation water salinity (S1-0.5, S2-2.0, S3-3.5 and S4-5.0 dS m-1) and four levels of foliar biostimulant spray [B1-0 (distilled water), B2-5, B3-10 and B4-5 mL L-1] using the commercial plant regulator Stimulate®. the following variables were evaluated: Number of leaves, leaf area, diameter stem, dry mass of leaves, stem, pods and total dry mass There was a significant interaction between the factors in all variables. The use of water with a conductivity of above 3.5 dS m-1 reduces the growth and production of cowpea grains with more severe effect in high doses of biostimulant. The use of biostimulant favors the growth and biomass, but is only efficient in the absence of salt stress. The use of Stimulate®  does not reduce the deleterious effect of salinity on the cowpea culture, and when used in high doses potentiated the effect of salinity. Keywords: Vigna unguiculata L., salinity, plant regulators

scholarly journals Morphophysiology of yellow passion fruit seedlings under application of nitrogen and potassium and irrigation with high-salinity water

2020 ◽  
pp. 1897-1908
Author(s):  
Francisco Romário Andrade Figueiredo ◽  
Jackson Silva Nóbrega ◽  
Reynaldo Teodoro de Fátima ◽  
Jean Telvio Andrade Ferreira ◽  
Micaela Benigna Pereira ◽  
...  
Keyword(s):  
Salt Water ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Passion Fruit ◽  
Saline Stress ◽  
Negative Effects ◽  
High Salinity Water ◽  
Nutritional Conditions ◽  
Electrical Conductivities ◽  
Yellow Passion Fruit

Salinity is one of the most problematic abiotic stresses in agriculture globally, especially in semi-arid regions. Thus, the application of nutrients, such as nitrogen and potassium to improve plant nutritional conditions may be a viable alternative to minimize the negative effects of saline stress. Therefore, the aim of this study was to evaluate the morphophysiological behavior of yellow passion fruit seedlings under varying nitrogen and potassium doses and irrigation with salt water. The experimental design was a randomized complete block with a 5 x 5 incomplete factorial scheme, generated from the Central Composite Design with five electrical conductivities of irrigation water (0.5, 0.98, 2.15, 3.32, and 3. 80 dS m-1) and five increasing doses of nitrogen and potassium (0.0, 29.08, 100.0, 170.92, and 200.0%). Leaf, stem, and root dry phytomass and gas exchange were evaluated 75 days after sowing. The increase in salinity had negative effects on the morphological and physiological characteristics of yellow passion fruit seedlings. The application of nitrogen and potassium positively influenced photosynthetic rate and leaf and root dry phytomasses. The application of nitrogen and potassium increased intercellular CO2 concentration and transpiration in yellow passion fruit seedlings under saline stress.

scholarly journals Physiological Indicators in Two Lettuce Cultivars Under Saline Stress

2021 ◽  
Vol 13 (4) ◽  
pp. 52
Author(s):  
Marcos Antonio Dantas de Oliveira ◽  
Paulo Torres Carneiro ◽  
Maria Claudjane Jerônimo Leite Alves ◽  
Thayse Valéria e Silva ◽  
Gilberto da Cruz Gouveia Neto ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Saline Water ◽  
Net Photosynthesis ◽  
Water Salinity ◽  
Saline Stress ◽  
Physiological Indicators ◽  
Osmotic Effect ◽  
Randomized Design ◽  
Salinity Levels ◽  
Green Index

Lettuce (Lactuca sativa L.) is considered as the main leafy vegetable in Brazil. In the last decades, there had been many changes in the predominant varietal types in the country, however, issues regarding the use of saline water inhibit the growth by the osmotic effect. The aim of this study is avaliate the effect of water salinity on physiological in lettuce cultivars. The experiment was carried out at the Alagoas Federal University, Arapiraca Campus, in a completely randomized design and with a 5 × 2 factorial scheme, with six replications. Five treatments of water salinity levels were analyzed (ECw: 0.14, 1.54, 2.94, 4.34, and 5.74 dS m-1 at 25 °C) in two types of lettuce crops (Saia Véia and Vitoria Verdinha). Stomatal conductance, net photosynthesis, transpiration rate, water use efficiency, leaf temperature, and green index were assessed at 10, 20, and 30 days after the application of the treatments. The saline stress caused by the increase in saline concentrations decreased the photosynthesis and transpiration rates, which were associated with the reduction of stomatal conductance in both cultivars. Nevertheless, Saia Véia cultivar was higher tolerance in all tested saline levels compared to Vitória Verdinha. The green index for Vitoria Verdinha was seven times higher when compared to Saia Véia from the lowest to the highest saline levels. The cultivars differ in salt sensitivity, which could be useful for producers to choose the cultivar that is most adapted to the region and breeders regarding improvement prospects for adaptation of the lettuce under saline stress. In addition to osmotic stress, which is the first to happen, there are others.

scholarly journals Auxin Applications Affect Posttransplant CO2 Exchange Rate and Growth of Bare-rooted Vinca [Catharanthus roseus (L.) G. Don] Seedlings

1999 ◽  
Vol 124 (3) ◽  
pp. 234-238 ◽  
Author(s):  
Marc van Iersel
Keyword(s):  
Exchange Rate ◽  
Catharanthus Roseus ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Co2 Exchange ◽  
Naphthaleneacetic Acid ◽  
Negative Effects ◽  
Transplant Shock ◽  
Whole Plant

Uprooting and transplanting seedlings can cause root damage, which may reduce water and nutrient uptake. Initiation of new roots and rapid elongation of existing roots may help minimize the negative effects of transplant shock. In this study, seedlings with four true leaves were transplanted into diatomaceous earth and the plants were transferred to a growth chamber, where they were treated with NAA (0, 0.025, 0.25, and 2.5 mg·L-1; 36 mL/plant). The effects of drenches with various amounts of 1-naphthaleneacetic acid (NAA) on the posttransplant CO2 exchange rate of vinca [Catharanthus roseus (L.) G. Don] were quantified. Whole-plant CO2 exchange rate of the plants was measured once every 20 minutes for a 28 day period. Seedlings treated with 0.025 or 0.25 mg·L-1 recovered from transplant shock more quickly than plants in the 0 and 2.5 mg·L-1 treatments. Naphthaleneacetic acid drenches containing 0.025 or 0.25 mg·L-1 increased whole-plant net photosynthesis (Pnet) from 10 days, dark respiration (Rdark) from 12 days, and carbon use efficiency (CUE) from 11 days after transplanting until the end of the experiment. The increase in CUE seems to have been the result of the larger size of the plants in these two treatments, and thus an indirect effect of the NAA applications. These differences in CO2 metabolism among the treatments resulted in a 46% dry mass increase in the 0.025 mg·L-1 treatment compared to the control, but shoot-root ratio was not affected. The highest rate of NAA (2.5 mg·L-1) was slightly phytotoxic and reduced the growth rate of the plants.

scholarly journals Initial Development of Safflower Submitted to Irrigation Water Salinity Levels

2018 ◽  
Vol 11 (1) ◽  
pp. 200
Author(s):  
William Fenner ◽  
Edna Maria Bonfim-Silva ◽  
Tonny José Araújo da Silva ◽  
Túlio Santos Martinez ◽  
Thiago Henrique Ferreira Matos Castañon ◽  
...  
Keyword(s):  
Irrigation Water ◽  
Saline Water ◽  
Dry Mass ◽  
Water Salinity ◽  
Saline Stress ◽  
Root Volume ◽  
Initial Development ◽  
Irrigation Water Salinity ◽  
Salinity Levels ◽  
Plant Emergence

Safflower cultivation is an alternative to tropical cropping systems, with a good rusticity and some tolerance to saline stress in some cultivars. With the increase of irrigated areas around the world, salinization of the soil is an inherent concern, being the management of irrigation and cultivated species fundamental. The objective of this study was to evaluate the growth and initial development of safflower culture submitted to irrigation water salinity levels. The experiment was carried out in a greenhouse in a completely randomized design consisting of five irrigation water salinity levels (0, 2, 4, 6 and 8 dS m-1) and six replications. The saline solution was prepared using NaCl and measured with a conductivity meter. Plant height, number of leaves and stem diameter at 26 and 41 days after emergence, and shoot dry weight were evaluated; root volume; root dry mass; total dry mass and dry root/shoot mass ratio at 41 days after plant emergence. There was no visual influence of salinity levels in the evaluations at 26 days after plant emergence. However, 41 days after plant emergence, the increase in salinity levels promoted a decrease in all analyzed variables, except for root volume. Safflower does not tolerate irrigation with saline water. The damages occur from 2 dS m-1, but the largest reductions in the initial development of safflower occur from 6 to 8 dS m-1.

scholarly journals Morphological and physiological changes in papaya seedlings irrigated with saline water and application of humic substances

2020 ◽  
Vol 11 ◽  
pp. e3290
Author(s):  
Thiago Jardelino Dias ◽  
Marcia Paloma Da Silva Leal ◽  
Everaldo Silva Do Nascimento ◽  
Mario Leno Martins Veras ◽  
Toshik Iarley da Silva ◽  
...  
Keyword(s):  
Salt Stress ◽  
Humic Substances ◽  
Saline Water ◽  
Salt Content ◽  
Net Photosynthesis ◽  
Co2 Concentration ◽  
Semiarid Region ◽  
Randomized Design ◽  
High Salt Content ◽  
Use Efficiency

In the northeast semiarid region water with high salt content is very common, which may negatively affect crops growth and development. Thus using possible salt stress attenuators is extremely important because it allows the use of saline waters for agricultural purposes. Among the possible attenuators of salt stress, humic substances stand out. This work was driven in order to evaluate the effect of the application of humic substances as a possible attenuator of salt stress from papaya seedlings irrigation. The experiment was conducted under entirely randomized design with five replications in a 4 x 4 factorial, regarding the four doses of humic substances (5, 10, 15 and 20g), and the electrical conductivity of the irrigation water (ECw 1.5; 3.0; 4.5 and 6 dS m-1). When it irrigates the papaya seedlings with water of 6.0 dS m-1 is recommended dose of 20 g of humic substances, which provided growth. Irrigation of papaya seedlings with high salinity (3.0 and 4.5 dS m-1) allied with application of 20 g of humic substances provide increased CO2 concentration, transpiration rate, instantaneous water use efficiency, carboxylation efficiency and chlorophyll b content, however, stomatal conductance, net photosynthesis and chlorophyll a content are reduced with increase of the ECw.

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