Physiological indices of okra under organomineral fertilization and irrigated with salt water¹

Índices fisiológicos de quiabeiro irrigado com água salina sob adubação organomineral

HIGHLIGHTS

Salt water reduces gas exchange in the okra crop, but organomineral fertilization mitigates these effects.

The use of organic and mineral fertilization is viable in okra crops under salt stress.

Organic fertilizer (100% bovine biofertilizer) decreases internal CO₂ concentration.

Key words: Abelmoschus esculentus; physiology; plant nutrition

ABSTRACT

Proper management of brackish water can increase plant production in the Brazilian semiarid region. Organomineral fertilization contributes to minimizing the harmful effects of salinity. As such, the present study aimed to assess the physiological indices of okra crops grown under organomineral fertilization and irrigated with salt water. A completely randomized design was used, in a 6 × 2 factorial scheme with six repetitions, corresponding to six types of fertilization: T1 - mineral fertilization with NPK; T2 - bovine biofertilizer; T3 - fertilization with plant ash; T4 - mineral fertilizer (50%) + bovine biofertilizer (50%); T5 - mineral fertilizer (50%) + plant ash (50%); T6 - control; and two electrical conductivities of the irrigation water (0.5 and 5.0 dS m^-1). The physiological indices of okra plants were analyzed 30 and 60 days after transplanting (DAT). Although salt stress negatively affects the physiological indices of okra, organomineral fertilization partially mitigates these effects. Thus, organic and mineral fertilizers are recommended in okra crops under saline conditions.

Key words: Abelmoschus esculentus; physiology; plant nutrition

RESUMO

O manejo adequado de águas salobras pode aumentar a produção vegetal no Semiárido brasileiro. A fertilização organomineral contribui para a minimização dos efeitos deletérios da salinidade. Nessa perspectiva, objetivou-se avaliar os índices fisiológicos do quiabeiro cultivado sob adubação organomineral e irrigado com água salina. O experimento foi no delineamento experimental inteiramente casualizado no esquema fatorial 6 x 2, com seis repetições, referente a seis formas de adubação: T1 - Adubação mineral com NPK; T2 - Adubação com biofertilizante bovino; T3 - Adubação com cinza vegetal; T4 - Adubo mineral (50%) + biofertilizante bovino (50%); T5 - Adubo mineral (50%) + cinza vegetal (50%); T6 - Controle; e a duas condutividades elétricas da água de irrigação (0,5 e 5,0 dS m^-1). Aos 30 e 60 dias após o transplantio, foram analisados os índices fisiológicos do quiabeiro. O estresse salino afeta de forma negativa os indicies fisiológicos da cultura do quiabo, no entanto, a fertilização organomineral atenua parcialmente os efeitos dos sais sobre a fisiologia do quiabeiro. Desta forma, recomenda-se o uso da adubação orgânica e mineral no cultivo do quiabeiro em condições de salinidade.

Palavras-chave: Abelmoschus esculentus; fisiologia; nutrição vegetal

Introduction

Okra [Abelmoschus esculentus (L.) Moench], a flowering plant in the family Malvaceae, with African origins, is primarily used for human consumption and has recently attracted interest from the industrial sector for fiber production. It is grown in tropical and subtropical areas due to its hardiness and low production costs (Marin et al., 2017; Torres et al., 2014; Sales et al., 2019).

In regions with a hot dry climate, such as the Brazilian semiarid, which is subject to drought at certain times of the year, irrigation is essential in order to safeguard production; however, limitations such as low quality water persist (Ribeiro et al., 2016).

The accumulation of ions such as Na⁺ and/or Cl^- in chloroplasts causes several disturbances in plant biomolecular processes, resulting in osmotic effects, limiting water transport and restricting stomatal opening as well as the photochemical processes involved (Silveira et al., 2016).

There are several alternatives that can be used to mitigate the effects of salt stress on plants, including the use of organic liquid biofertilizers (Souza et al., 2019), nitrogen or potassium fertilization, or a combination of these in the form of organomineral fertilizers (Santos et al., 2019).

Several sources have been studied and applied to soil under salt water irrigation, as reported by Sousa et al. (2020), who used organic bovine biofertilizer in okra plants, Guedes Filho et al. (2015), who fertilized sunflowers with urea, and Prazeres et al. (2015), who applied potassium chloride to cowpea.

In light of the above, the present study aimed to assess the physiological indices of okra plants under organomineral fertilization irrigated with salt water.

Material and Methods

The experiment was conducted from September to December 2018, in the Professor Luiz Antônio da Silva Teaching Garden of the University of International Integration of the Afro-Brazilian Lusophony (UNILAB), in Redenção, Ceará state (CE), Brazil. Climate in the region is classified as tropical wet, with rain predominantly occurring in summer and fall (Köppen, 1923).

The substrate used was obtained by mixing so-called arisco sand, sand and bovine manure at a ratio of 4:2:1, respectively. The chemical analysis results are presented in Table 1.

Table 1
Chemical characteristics of the substrate used in okra cultivation

OM	N	Ca2+	K+	Mg2+	Na+	H+ + Al3+	ECse	SB	P (mg kg-1)	CEC	V
(g kg-1)		cmolc kg-1					(dS m-1)			(%)
9.15	0.54	2.0	3.31	2.0	1.31	0.83	0.5	9.43	59	6.7	91

• OM - Organic matter; ECse - Electrical conductivity of the saturated extract of the substrate; SB - Sum of bases (Ca²⁺ + Mg²⁺ + Na⁺ + K⁺); CEC - Cation exchange capacity - [Ca²⁺ + Mg²⁺ + Na⁺ + K⁺ + (H⁺ + Al³⁺)]; V - Base saturation - (Ca²⁺ + Mg²⁺ + Na⁺ + K⁺/ CTC) x 100

A completely randomized design was used, in a 6 x 2 factorial scheme with six repetitions, in which the first factor corresponds to different types of fertilization: T1 - mineral fertilization with NPK (100% of the recommended dose); T2 - bovine biofertilizer (100%); T3 - fertilization with plant ash (100%); T4 - mineral fertilizer (50%) + bovine biofertilizer (50%); T5 - mineral fertilizer (50%) + plant ash (50%); T6 - control (no fertilization); and the second to two electrical conductivities of the irrigation water - ECw (0.5 and 5.0 dS m^-1).

Okra seeds (‘Santa Cruz 47’ cultivar) were sown in seed trays and transplanted to plastic pots containing 23 kg of substrate 15 days after seedling establishment, under full sun conditions.

Percolation lysimeters were prepared by drilling a hole into the bottom of each pot and attaching a hose to drain the water. To prevent leaks, the hoses were connected to 1 L PET bottles sealed with glue, which received the water drained each day.

Irrigation began 22 days after transplanting (DAT) and was performed daily using the percolation lysimeter method, supplying enough water every 24 hours to maintain the substrate at field capacity.

The salt water applied in irrigation was obtained in accordance with the methodology of Rhoades et al. (2000), whereby the amount of NaCl, CaCl₂.2H₂O and MgCl₂.6H₂O used to prepare the irrigation water was determined to obtain the desired ECw at a ratio of 7:2:1, from water used to supply the experimental area, which represents the control treatment (0.5 dS m^-1).

The mineral fertilization recommendations of Trani (2013) for okra, consisting of 80 kg ha^-1 of N, 100 kg ha^-1 of P₂O₅ and 60 kg ha^-1 of K₂O, were adopted.

The biofertilizer was prepared using fresh bovine manure via aerobic fermentation, with the addition of nonsaline water (0.5 dS m^-1) at a ratio of 1:1, for 30 days. Plant ash (from sugarcane burning) was added in treatments T3 (1.0 kg) and T5 (500 g).

Table 2 shows the mineral concentrations of the bovine biofertilizer and plant ash.

Table 2
Nutritional composition of the bovine biofertilizer and plant ash

Organic fertilizer	N	P	K+	Ca2+	Mg2+	Fe	Cu	Zn	Mn
	(g L-1)					(mg L-1)
Biofertilizer	0.82	1.40	1.0	2.5	0.75	141.60	1.92	68.2	14.72
Plant ash	0.40	1.13	54.4	28.7	13.9	7819.1	10.5	37.8	240.8

At 30 and 60 DAT, the following physiological indices were analyzed: photosynthesis (A), transpiration (E), stomatal conductance (g_s), internal CO₂ concentration (C_i) and leaf temperature (TL), using an infrared gas analyzer (LI 6400 XT, LICOR) in an open system, with an air flow rate of 300 mL min^-1; measurements were taken between 10 a.m. and 12 p.m. on fully expanded leaves. Instantaneous water use efficiency (WUEi) was calculated as the ratio between the net photosynthetic rate (An) and transpiration rate (E).

The data were submitted to analysis of variance and Tukey’s test, using Assistat 7.7 Beta software (Silva & Azevedo, 2016).

Results and Discussion

Analysis of variance demonstrated significant interaction between fertilization and salinity for the variable transpiration (E) at 30 and 60 DAT (Table 3).

Table 3
Analysis of variance summary for the variables photosynthesis (A), transpiration (E), stomatal conductance (gs), internal CO₂ concentration (Ci), leaf temperature (LT) and instantaneous water use efficiency (WUEi) in okra plants grown under organomineral fertilization with high and low salinity irrigation at 30 and 60 days after transplanting (DAT)

SV	DF	Mean squares
		A	E	gs	Ci	LT	WUEi
		30 DAT
Fertilization (F)	5	21.45ns	7.82**	8.91×10-3ns	713.09*	7.12**	0.77**
Salinity (S)	1	412.75**	23.83**	0.19ns	24110.41**	38.45**	0.36*
F x S	5	18.80ns	3.85**	8.81×10-3ns	524.40ns	5.88**	0.82**
Treatments	11	57.92**	7.47**	0.02**	2754.35**	9.40**	0.76**
Residue	36	8.55	0.81	1.96×10-3	249.02	0.12	0.05
CV (%)		15.43	11.81	14.68	7.46	1.07	6.71
		60 DAT
Fertilization (F)	5	10.19ns	1.39ns	0.01ns	1877.85ns	2.28ns	0.86ns
Salinity (S)	1	374.30**	8.82**	0.14**	90.97ns	19.13ns	10.21**
F x S	5	14.13ns	1.96*	0.01ns	1351.37ns	2.21ns	1.65ns
Treatments	11	45.08**	2.32**	0.02**	1476.09ns	3.78*	2.07ns
Residue	36	6.29	0.58	7.52×10-3	757.81	0.25	1.05
CV (%)		24.93	21.97	22.88	10.41	1.46	34.74

• SV - Sources of variation; DF - Degrees of freedom; *; ** and ^{ns -} Significant according to F test at p ≤ 0.05, p ≤ 0.01 and not significant, respectively; CV - Coefficient of variation

Additionally, this interaction significantly influenced leaf temperature (LT) and instantaneous water use efficiency (WUEi) at 30 DAT. Salinity was significant for photosynthesis (A) at 30 and 60 DAT, and for stomatal conductance (gs) and WUEi at 60 DAT. Finally, at 30 DAT, internal CO₂ concentration (Ci) showed significant results for fertilization and salinity.

Figure 1 shows that the photosynthetic rate declined at 30 and 60 DAT (Figures 1A and B, respectively), when plants were irrigated with highly saline water (5.0 dS m^-1).

Figure 1
Mean photosynthesis values of okra plants irrigated under high and low salinity, at 30 (A) and 60 (B) days after transplanting (DAT)

The lower photosynthetic rates due to salt stress can be attributed to the decline in cell expansion that precedes photosynthesis inhibition, causing partial stomatal closing and thereby reducing the CO2 available to leaves (Gomes et al., 2015). This result can be justified by decreased stomatal conductance in the present study (Figure 2). Nascimento et al. (2012) found that salt stress causes an imbalance between the production and removal of reactive oxygen species (ROS). This increases ROS levels and triggers oxidative stress, with a series of negative implications for metabolic mechanisms associated with photosynthesis.

Similar results were reported by Sousa et al. (2020) for okra plants irrigated at an ECw of 2.0; 3.0; 4.0 and 5.0 dS m^-1 when compared to controls (1.0 dS m^-1), and by Pereira Filho et al. (2019) in fava bean.

At 30 DAT, salt stress reduced the transpiration rate of okra (Table 4) by 31.7; 29.1 and 19.4% in treatments T1, T4 and T6, respectively, whereas the rise in ECw from 0.5 to 5.0 dS m^-1 resulted in declines of 34.2, 49.0, 37.1 and 28.5% in T1, T2, T3 and T5, respectively (Table 4).

Table 4
Mean transpiration values (E) in okra plants grown under organomineral fertilization and irrigated with salt water, at 30 and 60 days after transplanting (DAT)

Fertilizers	E (mmol m2 s-1)
	30 DAT		60 DAT
	Electrical conductivity (dS m-1)
	0.5	5.0	0.5	5.0
T1	8.52 abA	5.82 bB	3.88 aA	2.55 bB
T2	6.43 bA	5.84 bA	3.98 aA	2.03 bB
T3	7.75 bA	6.72 abA	3.80 aA	2.39 bB
T4	10.43 aA	7.39 abB	3.77 aA	4.26 aA
T5	7.73 bA	8.42 aA	4.24 aA	3.03 bB
T6	9.18 abA	7.40 abB	3.69 aA	3.95 abA

• Means followed by the same lowercase letter in the column and uppercase letter in the row do not differ according to Tukey’s test at p ≤ 0.05; T1 - 100% mineral fertilization; T2 - 100% bovine biofertilizer; T3 - 100% plant ash; T4 - 50% mineral + 50% bovine; T5 - 50% mineral + 50% ash and T6 - Control

The effect of T1 for both assessments may have been due to the positive effect of photosynthesis in treatments involving irrigation with low saline water (0.5 dS m^-1). However, highly saline water (5.0 dS m^-1) decreased the transpiration rate (partial stomatal closure), reducing CO₂ absorption (Prazeres et al., 2015).

In order to adapt to excess salt, plants lower leaf water potential (by reducing the transpiration rate) in order to maintain a gradient that favors water absorption and flow in the soil-root-stem system, which typically increases the expenditure of metabolic energy (Taiz et al., 2017).

Similar data were reported by Sousa et al. (2020) in okra, whereby the use of a bovine biofertilizer as low saline levels (1.0 and 2.0 dS m^-1) positively affected the transpiration rate. Additionally, Prazeres et al. (2015) found that mineral fertilization increased transpiration in bean plants only when low salinity water was used (0.7 dS m^-1).

As shown in Figure 2, the salinity of irrigation water exhibited an isolated effect on stomatal conductance at 60 DAT.

Figure 2
Mean stomatal conductance (gs) values of okra plants irrigated under high and low salinity, at 60 days after transplanting (DAT)

Stomatal closure declines in plants under salt stress, reducing CO₂ assimilation in the leaf mesophyll and directly affecting internal CO₂ concentration as well as photosynthesis (Taiz et al., 2017).

Since sodium in the soil occurs primarily as cations (Na⁺), it competes for absorption sites in the roots with other minerals such as potassium, (K⁺), resulting in possible potassium deficiency.

Melo et al. (2014) found that K accumulation in plants favors an osmotic gradient that facilitates water movement, regulating stomatal opening and playing a vital role in cell turgidity. However, these functions are significantly compromised in saline environments due to increased stomatal resistance and, consequently, lower gs.

Similar results were obtained by Sousa et al. (2020), who observed decreased stomatal conductance in okra plants irrigated with salt water. Souza et al. (2019) observed that an increase in salinity from 0.5 to 4.5 dS m^-1 lowered stomatal conductance in fava beans.

In the present study, analysis of the effect of fertilization (Figure 3) on internal CO₂ concentration in okra at 30 DAT indicated that mineral fertilizer (T1) produced the greatest internal accumulation of this compound (222.71 µmol CO₂ mol^-¹).

Figure 3
Mean internal CO₂ concentration in okra plants under organomineral fertilization

The high internal carbon concentration observed may be related to greater stomatal opening, evident in stomatal conductance at 30 DAT (Figure 2). In general, greater stomatal opening favors the entry of CO₂ from atmosphere into the leaf mesophyll, increasing its concentration in the substomatal cavity (Prazeres et al., 2015).

According to Figure 4, at 30 DAT the increase in salinity reduced internal CO₂ concentration (189.04 µmol mol^-¹) when compared to plants irrigated with water at 0.5 dS m^-¹ (233.86 µmol mol^-¹).

Figure 4
Mean internal CO₂ concentration (Ci) in okra plants irrigated under high and low salinity, at 30 days after transplanting (DAT)

This response can be attributed to the fact that higher salt concentrations trigger soil osmotic pressure, restricting gs and CO₂ assimilation (Ribeiro et al., 2016). The proportional reductions in A (Figure 1) and gs (Figure 2) caused by salt stress indicate that the decline in Ci may be related to osmotic effects, which limit the entry of CO₂for assimilation.

Silva et al. (2019) reported contrasting results, whereby a one unit increase in the electrical conductivity of irrigation water (0.5; 2.5; 5.0; 7.5 and 10.0 dS m^-1) raised the internal CO₂ concentration of sorghum.

With respect to the leaf temperature of okra (Table 5), a significant interaction was observed at 30 DAT. Temperature increased as the electrical conductivity of irrigation water rose. The highest LT values were recorded in plants fertilized with plant ash (35.58 °C), followed by 50% mineral fertilizer + 50% bovine biofertilizer (35.47 °C).

Table 5
Mean leaf temperature values (LT) in okra plants grown under organomineral fertilization and irrigated with salt water, at 30 days after transplantig (DAT)

Fertilizers	LT (°C)
	Electrical conductivity (dS m-1)
	0.5	5.0
T1	30.94 dB	33.24 dA
T2	31.57 dB	35.31 abA
T3	32.43 cB	35.58 aA
T4	34.37 aA	35.47 aA
T5	32.80 bcA	34.27 cA
T6	33.53 bB	34.72 bcA

• Means followed by the same lowercase letter in the column and uppercase letter in the row do not differ according to Tukey’s test at p ≤ 0.05; T1 - 100% mineral fertilization; T2 - 100% bovine biofertilizer; T3 - 100% plant ash; T4 - 50% mineral + 50% bovine; T5 - 50% mineral + 50% ash and T6 - Control

Leaf temperature is inversely proportional to transpiration rate, that is, as transpiration decreased with increased salinity (Table 5), leaf water content declined and leaf temperature rose.

Lacerda et al. (2011) reported contrasting results, whereby salt water irrigation increased the solar radiation intercepted by the basal leaves of cowpea plants, improving the photosynthesis rate and leaf temperature.

In regard to WUEi, the addition of salt to irrigation water did not expose plants to stress at 30 DAT, demonstrating that okra is resistant to salt water up to this developmental stage (Table 6).

Table 6
Mean instantaneous water use efficiency values (WUEi) in okra plants grown under organomineral fertilization and irrigated with salt water, at 30 days after transplantig (DAT)

Fertilizers	WUEi (mmol m-2 s-1 (mol H2O m-2 s-1)-1)
	Electrical conductivity (dS m-1)
	0.5	5.0
T1	3.48 bcB	4.20 aA
T2	4.35 aA	3.74 abB
T3	3.84 bA	3.44 bB
T4	2.72 dB	3.76 abA
T5	3.50 bcA	3.47 bA
T6	3.15 cdA	3.48 bA

• Means followed by the same lowercase letter in the column and uppercase letter in the row do not differ according to Tukey’s test at p ≤ 0.05; T1 - 100% mineral fertilization; T2 - 100% bovine biofertilizer; T3 - 100% plant ash; T4 - 50% mineral + 50% bovine; T5 - 50% mineral + 50% ash and T6 - Control

By contrast, Nobre et al. (2014) studied the growth, water consumption and use efficiency of castor bean plants under salt and nitrogen stress and found a decline in efficiency when the EC of water increased. However, in the present study, analysis of the effect of water at 0.5 dS m^-¹ demonstrated that the combined action of 50% mineral fertilizer + 50% bovine biofertilizer exposed okra plants to stress (2.72 µmol m^-2 s^-1 (mol H₂O m^-2 s^-1)^-1). The highest WUEi was obtained under 100% bovine fertilization (4.35 µmol m^-2 s^-1 (mol H₂O m^-2 s^-1)^-1). The superior performance of this input in terms of WUEi may be associated with the gradual availability of N, P and K, with adequate amounts favoring better plant-water relations.

Plants responded positively to treatments involving irrigation with saline water at 5.0 dS m^-¹ and fertilization, followed by the control. Additionally, the greatest efficiency was obtained with mineral fertilization, with 4.20 (µmol m^-2 s^-1 (mol H₂O m^-2 s^-1)^-1). The chemical attributes of this fertilizer may have promoted osmotic adjustment in the roots, ensuring better water absorption.

The WUEi of okra plants at 60 DAT was negatively affected by increased electrical conductivity. As shown in Figure 5, plants irrigated with 0.5 dS m^-¹ water exhibited higher WUEi (µmol m^-2 s^-1 (mol H₂O m^-2 s^-1)^-1) when compared to 5.0 dS m^-¹ (µmol m^-2 s^-1 (mol H₂O m^-2 s^-1)^-1).

Figure 5
Mean instantaneous water use efficiency (WUEi) in okra plants irrigated under high and low salinity, at 60 days after transplantig (DAT)

Dias et al. (2016) reported that a higher salt concentration in irrigation water lowers soil osmotic and water potential, preventing the crop from absorbing the available water. Similar results were found by Lima et al. (2018), who observed reduced instantaneous water use efficiency at high saline levels in cotton, with a linear decrease of 8.17% per unit increase in ECw.

Conclusions

1. Although salt stress negatively affects the physiological indices of okra, organomineral fertilization partially mitigates these effects.

2. Organic and mineral fertilizers are recommended in okra crops under saline conditions.

3. Irrigation with water at 5.0 dS m^-1 increases the leaf temperature of okra plants.

Literature Cited

• Dias, N. da S.; Blanco, F. F.; Souza, E. R. de; Ferreira, J. F. da S.; Sousa Neto, O. N. de; Queiroz, I. S. R. de. Efeitos dos sais na planta e tolerância das culturas à salinidade. In: Gheyi, H. R.; Dias, N. da S.; Lacerda, C. F. de; Gomes Filho, E. Manejo da salinidade na agricultura: Estudos básicos e aplicados. 2.ed. Fortaleza: Byte Systems - Soluções Digitais, 2016. Cap. 11. p.151-161.
• Gomes, K. R.; Sousa, G. G. de; Lima, F. A.; Viana, T. D. de A.; Azevedo, B. D. de; Silva, G. D. da. Irrigação com água salina na cultura do girassol (Helianthus annuus L.) em solo com biofertilizante bovino. Irriga, v.20, p.680-693, 2015. https://doi.org/10.15809/irriga.2015v20n4p680
  » https://doi.org/10.15809/irriga.2015v20n4p680
• Guedes Filho, D. H.; Santos, J. B. dos; Greyi, H. R.; Cavalcante, L. F.; Santos Junior, J. A. Componentes de produção e rendimento do girassol sob irrigação com águas salinas e adubação nitrogenada. Irriga, v.20, p.514-527, 2015. https://doi.org/10.15809/irriga.2015v20n3p514
  » https://doi.org/10.15809/irriga.2015v20n3p514
• Köppen, W. P. Die klimate der erde: Grundriss der klimakunde. Berlin: Walter de Gruyter & So. 1923. 369p. https://doi.org/10.1515/9783111491530
  » https://doi.org/10.1515/9783111491530
• Lacerda, C. F. de; Silva, F. B. da; Neves, A. L. R.; Silva, F. L. B. da; Gheyi, H. R.; Ness, R. L. L.; Gomes Filho, E. Influence of plant spacing and irrigation water quality on a cowpea-maize cropping system. International Research Journal of Agricultural Science and Soil Science, v.1, p.163-167, 2011.
• Lima, G. S. de; Dias, A. S.; Gheyi, H. R.; Soares, L. A. dos A.; Andrade, E. M. G. Irrigação com águas salinas e adubação nitrogenada no cultivo do algodoeiro de fibra colorida. Revista Caatinga, v.31, p.151-160, 2018. https://doi.org/10.1590/1983-21252018v31n118rc
  » https://doi.org/10.1590/1983-21252018v31n118rc
• Marin, M. V.; Santos, L. S.; Gaion, L. A.; Rabelo, H. O.; Franco, C. A.; Diniz, G. M.; Braz, L. T. Selection of resistant rootstocks to Meloidogyne enterolobii and M. incognita for okra (Abelmoschus esculentus L. Moench). Chilean Journal of Agricultural Research, v.77, p.58-64, 2017. https://doi.org/10.4067/S0718-58392017000100007
  » https://doi.org/10.4067/S0718-58392017000100007
• Melo, A. S. de; Silva Júnior, C. D.; Fernandes, P. D.; Brito, M. E. B.; Sobral, L. F.; Suassuna, A. F.; Viégas, P. R. A.; Ferraz, R. L. S. Teor de clorofila e macronutrientes no tecido foliar de Musa sp ‘Prata-Anã’ sob fertirrigação. African Journal of Agricultural Research, v.9, p.1714-1720, 2014.
• Nascimento, R.; Nascimento, D.; Silva, D. A.; Alves, A. G. Índice SPAD e partição de biomassa em plantas de feijão-caupi submetidas ao estresse salino. Revista Educação Agrícola Superior, v.27, p.128-132, 2012. https://doi.org/10.12722/0101-756X.v27n02a09
  » https://doi.org/10.12722/0101-756X.v27n02a09
• Nobre, R. G.; Lima, G. S. de; Gheyi, H. R.; Soares, L. A. dos A.; Silva, A. O. da. Crescimento, consumo e eficiência do uso da água pela mamoneira sob estresse salino e nitrogênio. Revista Caatinga , v.27, p.148-158, 2014.
• Pereira Filho, J. V.; Viana, T. V. de A.; Sousa, G. G. de; Chagas, K. L.; Azevedo, B. M. de; Pereira, C. C. M. de S. Physiological responses of lima bean subjected to salt and water stresses. Revista Brasileira de Engenharia Agrícola e Ambiental, v.23, p.959-965, 2019. https://doi.org/10.1590/1807-1929/agriambi.v23n12p959-965
  » https://doi.org/10.1590/1807-1929/agriambi.v23n12p959-965
• Prazeres, S. S.; Lacerda, C. F. de; Barbosa, F. E. L.; Amorim, A. V.; Araujo, I. C. da S.; Cavalcante, L. F. Crescimento e trocas gasosas de plantas de feijão-caupi sob irrigação salina e doses de potássio. Revista Agro@mbiente, v.9, p.111-118, 2015. https://doi.org/10.18227/1982-8470ragro.v9i2.2161
  » https://doi.org/10.18227/1982-8470ragro.v9i2.2161
• Rhoades, J. P.; Kandiah, A.; Mashali, A. M. Uso de águas salinas para a produção agrícola. Estudos FAO 48, 2000. 117p.
• Ribeiro, M. R.; Ribeiro Filho, M. R.; Jacomine, P. K. T. Origem e classificação dos solos afetados por sais. In: Gheyi, H. R.; Dias, N. da S.; Lacerda, C. F. de; Gomes Filho, E. Manejo da salinidade na agricultura: Estudos básicos e aplicados. 2.ed. Byte Systems - Soluções Digitais, 2016. Cap. 2. p.9-15.
• Sales, J. R. da S.; Sousa, G. G. de; Cavalcante, F.; Moraes, J. G. L.; Leite, K. N.; Viana, T. V. de A. Production and quality of okra fruits submitted to doses and types of biofertilizers. Journal of Agricultural Science, v.11, p.507-514, 2019. https://doi.org/10.5539/jas.v11n4p507
  » https://doi.org/10.5539/jas.v11n4p507
• Santos, S. S.; Fernandes, P. D.; Queiroz, M. F. de; Arriel, N. H. C.; Ribeiro, V. H. de A.; Fernandes, J. D. Physiology and production of sesame genotypes BRS-Seda and Preto under organomineral fertilization. Revista Brasileira de Engenharia Agrícola e Ambiental , v.23, p.914-918, 2019. https://doi.org/10.1590/1807-1929/agriambi.v23n12p914-918
  » https://doi.org/10.1590/1807-1929/agriambi.v23n12p914-918
• Silva, F. de A. S. e; Azevedo, C. A. V. de. The Assistat Software Version 7.7 and its use in the analysis of experimental data. African Journal of Agricultural Research , v.11, p.3733-3740, 2016. https://doi.org/10.5897/AJAR2016.11522
  » https://doi.org/10.5897/AJAR2016.11522
• Silva, M. L. dos S.; Sousa, H. G. de; Silva, M. L. dos S.; Lacerda, C. F. de; Gomes-Filho, E. Growth and photosynthetic parameters of saccharine sorghum plants subjected to salinity. Acta Scientiarum.Agronomy, v.41, p.1-9, 2019. https://doi.org/10.4025/actasciagron.v41i1.42607
  » https://doi.org/10.4025/actasciagron.v41i1.42607
• Silveira, J. A. G.; Silva, S. L. F.; Silva, E. N. Mecanismo biomoleculares envolvidos com a resistência ao estresse salino em plantas. In: Gheyi, H. R.; Dias, N. S.; Lacerda, C. F.; Gomes-Filho, E. Manejo da Salinidade na Agricultura: Estudos Básicos e Aplicados. 2. ed. Byte Systems - Soluções Digitais, 2016. Cap. 13. p. 181-197.
• Sousa, G. G. de; Mendonça, A. de M.; Sales, J. R. da S.; Silva Júnior, F. B. da; Moraes, J. G. L.; Souza, J. T. M. de. Morphophysiological characteristics of okra plants submitted to saline stress in soil with organic fertilizer. Comunicata Scientiae, v.11, p.1-8, 2020. https://doi.org/10.14295/cs.v11i0.3241
  » https://doi.org/10.14295/cs.v11i0.3241
• Souza, M. V. P.; Sousa, G. G. de; Sales, J. R. da S.; Freire, M. H. C. da; Silva, G. L.; Viana, T. V. de A. Saline water and biofertilizer from bovine and goat manure in the Lima bean crop. Revista Brasileira de Ciências Agrárias, v.14, p.1-8, 2019. https://doi.org/10.5039/agraria.v14i3a5672
  » https://doi.org/10.5039/agraria.v14i3a5672
• Taiz, L.; Zeiger, E.; Møller, I. M.; Murphy, A. Fisiologia e desenvolvimento vegetal. Artmed Editora, 2017.
• Torres, S. B.; Silva, F. G. D.; Gomes, M. D. D. A.; Benedito, C. P.; Pereira, F. E. C. B.; Silva, E. C. D. Differentiation of seeds lots of okra by accelerated aging test. Ciência Rural, v.44, p.2103-2110, 2014. https://doi.org/10.1590/0103-8478cr20120886
  » https://doi.org/10.1590/0103-8478cr20120886
• Trani, P. E.; Passos, F. A.; Teodoro, M. C. C. L.; Santos, V. J. dos; Frare, P. Calagem e Adubação para a Cultura do Quiabo. Instituto Agronômico de Campinas, 2013.

• ¹ Research developed at Universidade da Integração Internacional da Lusofonia Afro-Brasileira, Redenção, CE, Brazil

Edited by

• Edited by: Hans Raj Gheyi

Publication Dates

• Publication in this collection
  09 Apr 2021
• Date of issue
  July 2021

History

• Received
  06 Dec 2019
• Accepted
  06 Mar 2021
• Published
  26 Mar 2021