Seed nanopriming with zinc oxide improves wheat growth and photosynthetic performance in wheat under drought stress

doi:10.21203/rs.3.rs-2353450/v1

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Seed nanopriming with zinc oxide improves wheat growth and photosynthetic performance in wheat under drought stress

https://doi.org/10.21203/rs.3.rs-2353450/v1

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Wheat is the most important cereal crop in the world. On the eve of climate and water scarcity, the use of different approaches such as the use of nutrients and organic or inorganic substances to increase drought tolerance and improve the yield in a wheat crop is necessary. The present study was conducted to cope with the problem of water deficit in wheat through ZnO nanoparticles (NPs). Wheat seeds (Ujala-16 and Zincol-16) were primed with different doses of ZnO NPs (40. 80, 120, and 160 ppm) under water deficit stress (No-stress and withholding water stress). Untreated seeds were also used as a control treatment. Results showed that drought stress decreased the shoot fresh (4.66 to 5.72 g) and dry weight (1.91g to 2.35g), shoot length (24.36 to 29.89 cm), root fresh (0.24 to 0.29 g) and dry weight (0.010 g) in both varieties of wheat. However, seed priming with ZnO at 80 and 120 ppm increased the fresh (8.07 to 10.09 g in Ujala-16 and 8.99 to 10.66 g in Zincole-16) and dry weight (3.31 to 4.14 g in Ujala-16 and 3.69 to 4.38 g in Zincole-16) of wheat plants. However, the maximum improvement in dry weight was observed under well-watered conditions (4.29 to 4.96 g in Ujala-16 and 4.62 to 5.45 g in Zincole-16). Similarly, ZnO NPs increased the chlorophyll a (1.73 mg/g FW in Ujala-16 and 1.75 mg/g FW in Zincole-16) b (0.70 mg/g FW in Ujala-16 and 0.71 mg/g FW in Zincole-16) and total chlorophyll content (2.43 mg/g FW in Ujala-16 and 2.46 mg/g FW in Zincole-16) in wheat by improving the activity of antioxidant and proline content of wheat. Similarly, plant nutrients such as Ca, Mg, Fe, N, P, K, and Zn contents increased in wheat plants after priming the seeds with ZnO NPs. Zincol-16 was responsive as compared to Ujala-16 however, ZnO NPs increase the growth and development of both wheat varieties under well-watered (control/No-stress) and withholding water stress. Thus, seed priming with ZnO NPs has the potential to alleviate the adverse effects of water deficits.

Seed priming

Morphology

Leaf Pigments

Antioxidant

Nutrient Analysis

zinc oxide

Drought stress

Wheat

Wheat (Triticum aestivum L.) is an important cereal crop and staple food for millions of people around the world (FAO, 2020). On the eve of climate change and the increasing food demand of the world’s population, an increase in wheat yield and productivity is compulsory (Hussain et al. 2014; Farooq et al. 2020). It is predicted that if the current changes in climate continue, then by 2100, wheat production will reduce by 5–50% (Bandara, and Cai, 2014; Aryal, et al. 2019). To address the climate challenges and to increase global food production, innovative techniques or approaches are very essential in modern agriculture. The use of nanotechnology in agriculture and its allied sciences is a rapidly increasing since the last decade. The application of nanomaterials or nanoparticles to enhance plant growth and yield in normal and stressful conditions is a relatively new practice (Zhao et al., 2020). It has been observed and further expected that nanotechnology and nanoparticles have the potential to revolutionize modern agriculture and can play a significant role in crop production and food security (Upadhyaya et al., 2017; Zhao et al., 2020). During the past several years, many products and patents comprising engineered nanoparticles such as nano fertilizers, nano pesticides, and nanosensors have been synthesized and used in agriculture to increase the sustainability and efficiency of agricultural practices (Shang et al., 2019). Recent research shows that nanoparticles have positive impacts on plant growth and yield (Zhao et al., 2020; Fincheira et al., 2021). Nanoparticles help to increase the nutrient use efficiency of plants because of their small size, nanoparticles cover more surface area and may directly involve in the physiological functions of plants (Usman et al., 2020). Various methods have been used to apply nanoparticles to plants such as seed coating, soil application, foliar spray, etc. The application of nanoparticles through seed priming is a new innovative technique to improve seed vigor, which is a prerequisite for better stand establishment under normal or even stressful environments (do Espirito Santo Pereira et al., 2021). In priming, seeds are soaked in water (hydropriming) and aerated solution (osmopriming) for a specific period that can trigger the metabolic processes generally activated during the early phase of germination (pre-germinative metabolism) and therefore increases the rate of germination and filed emergence (Hussain et al. 2014; Farooq et al. 2020). Different priming solutions (polyethylene glycol, hormones, nutrients, organic salts, etc.). these help the plant under the biotic stresses through their different properties and effectiveness. These help the plant to stand in stress. (Sytar et al., 2019; Farooq et al. 2020). Recently, many metal-based nanoparticles (NPs) such as gold (Au NPs), silver (Ag NPs), iron (Fe NPs), copper (Cu NPs), zinc oxide (ZnO NPs), zinc (Zn NPs), and carbon-based NPs fullerene and carbon nanotubes) have been used as seed pre-treatment agents in different crop species (Singla et al. 2019; Yao et al. 2021; Rajput et al. 2021). Among various studies using nanoparticles,

By the investigated data only a few researchers have used nanoparticles for seed priming (nanopriming) but these used different mechanisms from that of pre-sowing treatment. The studies of nano-priming on seed germination and early stand establishment and plant growth in wheat under normal and stressful conditions have not been elucidated so far. Zinc (Zn) is an essential micronutrient that is required for plant development, and growth and takes part or a component of > 300 proteins and plant enzymes (Ahmad et al. 2020; Hassan et al. 2020). Zn is needed for a variety of physiological functions such as pollination, growth regulation, antioxidant function, protein synthesis, photosynthesis, maintenance of biological membranes, and detoxify the toxic oxygen free radicals, and gene expression under normal and stressful conditions (Zhang et al. 2020; Suganya et al. 2020; Kaur and Garg, 2021).

ZnO and Zn Sulfate are used as fertilizer. The ZnO and Zn- sulfates are commonly applied to fulfill the deficiency of Zn in plants. the main problem is the availability of zinc to plants due to the lack of Zn solubility in soil (Barman et al. 2018; He et al. 2021). On the other hand, ZnO NPs can overcome this problem due to their high solubility, availability, and reactivity to plants (Rai-Kalal and Jajoo, 2021). zinc oxide nanoparticles among metal oxide nanoparticles have drawn the attention of researchers owing to their unique photo-oxidizing, physiological and biochemical capacity, and their unique functions in plant physiology (Ali, 2020; Rai-Kalal and Jajoo, 2021). Seed priming with NPs of ZnO was shown to increase the Zn content in the primed seeds thereby improving seedling vigor, growth, and final crop yields (Itroutwar et al. 2020; Rai-Kalal and Jajoo, 2021). Studies by Tului et al. (2021) The application of nanoparticles of ZnO had positive effects on the growth of chickpeas (Cicer arientinum), mung bean (Vigna radiata) (Manivannan et al. 2021), cucumber (Ghani et al. 2022), alfalfa (Tabande et al. 2022) and tomato (Hosseinpour et al. 2020). Thus, keeping in view the applications of ZnO nanoparticles (NPs), the present study was planned where wheat seeds (Triticum asetivum) were primed with ZnO NPs to observe the effect of ZnO NPs on seed germination, grain yield, and plant growth as well as biochemicals parameters and photosynthetic parameters in wheat plants.

Wheat seeds Zincol-16 (fortified) and Ujala-16 (non-fortified) were used to investigate the impact of ZnO NPs on the germination of seed, physiology, and growth of the wheat plant. Characterization of ZnO NPs was done by the manufacturer using UV–Visible spectroscopy, Transmission electron microscopy (TEM), and X-Ray Diffraction (XRD). The purity of obtained ZnO NPs was 99.99%. For seed priming, ZnO NPs solutions such as 40, 80, 120, and 160 ppm were prepared and then seeds of both wheat varieties were primed for 12 hours (h) at 25^oC. Unprimed seeds (control treatment) were used as control. After 12 h of priming, seeds were dipped in distilled water washed three times (three min for each), and shifted to the dry place for drying back to the original moisture content. The seed was pickup and added into the bag for preserved and stored at room temperature at a safe place until further use in the experiment. An experiment was conducted in pots at a wirehouse, Islamia University, Bahawalpur. Pots were separated into two groups, 1 group was kept at well-watered conditions (control plants) while the other group was given withholding water stress four weeks after the sowing. In each pot, 10 seeds were sown but after seedling establishment, 5 healthy plants were kept in pots. Fertilizers such as nitrogen (N), phosphorus (P), and potash (P) were used at 120-90-60 kg N, P, K ha^− 1. A whole quantity of potash fertilizer and phosphorus fertilizer and half a dose of N were mixed with soil and then filled with the pots. The remaining nitrogen was added during one sit of tillering. No herbicide was used and weeds germinated in pots were removed with hands. The data of the following parameters were recorded during the research.

2.1 Agronomic and growth parameters

Growth and Agronomic parameters such as shoot and root length, fresh weight, and dry weight were noted by selecting random plants from each treatment. The roots and shoot were placed into the oven at 80^o until a constant weight was obtained. These are placed after measuring the fresh-weight roots and shoots one by one through sensitive-digital balance. Plant height was measured through meter rot. Similarly, the leaf area per plant was noted through the leaf area meter.

2.2 Physiological and biochemical parameters

The youngest and most mature plant leaf (2nd top leaf) was to determine the leaf water potential from each treatment. The solander-type pressure chamber is used to determine the potential between 8:00 to 10:00 a.m. In case of relative water content, the flag leaf of wheat plants was detached and weighed using a digital electrical balance (Choy, MK-500C) and then the leaves were dipped in the test tube containing distilled water for 24 hr. After 24 hr, leaves were taken out and wiped with tissue paper, and their turgid weight (TW) was noted. Then the leaves were dried at 70^oC for 72 hr to record their dry weight (DW). Due to this formula, the relative water content was noted as

RWC = [(FW-DW) / (RW-DW)] x 100 (Pieczynski et al. 2013)

For investigation of chlorophyll a, b, and total chlorophyll, the sample of 100 mg leaves from treated and untreated plants from each treatment was taken and placed in 20 mL of chilled acetone (80% v/v). At 663 and 645 nm, the absorption was measured using a spectrophotometer (AA-7000, SHIMADZU). The chlorophyll a, b, content and total Chl content were determined using the following equations (Arnon,1949)

Chlorophyll a (mg/g FW) = 12.7 (A₆₆₃) − 2.69 (A₆₄₅)] × V} ÷ (1000 × W)

Chlorophyll b (mg/g FW) = 22.9 (A₆₄₅) − 4.68 (A₆₆₃)] × V} ÷ (1000 × W)

Total chlorophyll (mg/g FW) = 20.2 (A₆₄₅) + 8.02 (A₆₆₃)] × V} ÷ (1000 × W)

For total proline content, 0.5 g fresh leaf material was grounded and mixed in 10 mL of 3% sulfosalicylic acid (Bates et al. 1973), and then filtered through Whatman No. 40 filter paper. The filtrate material of 2 mL was taken in a 25 mL test tube and left for reaction. Then added 2 mL of acid ninhydrin solution and 2 mL of glacial acetic acid were and the test tubes were heated at 100'C. After completing all the reactions, its absorbance was measured at 520 nm through a spectrophotometer (AA-7000, SHIMADZU). The proline concentration was calculated from the standard curve and determined on a fresh weight basis as follows

Proline (µmoles g^− 1 FW) = [(µg proline/mL)×mL toluene)/115.5 µg/µmole]/[(g sample)/5]

Antioxidant enzymes activities such as peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase were noted through spectrophotometer (AA-7000, SHIMADZU). Leaves were homogenized in a medium composed of 50 mM phosphate buffer with 7.0 pH and 1 mM dithiothreitol as described by Cakmak (2000) and Dixit et al. (2001).

2.3 Plant nutrient analysis

For plant nutrients analysis, firstly taken 0.5 g of dried ground material was in digestion tubes, and added 5 ml of concentrated H₂SO₄ to each test tube (Wolf, 1982). All the tubes were placed in an incubator at room temperature and 0.5mL of H₂O₂ (35%) was taken poured down on the sides of the tube called the digestion tube, and heated at 350C temperature continuously for another 30 min after ported the tubes in digestion block heat until fumes were produced. After heating the tube was removed from the block and stayed for the cooling process. Then add 0.5 ml of H₂O₂. The H₂O_{2 was} added slowly and the tube was placed again into the digestion block. These steps are repeated till the material is cooled and colorless. In the Volumetric flask, the extract was maintained up to 50ml. after this, the filtration process was formed to determine the Ca, Mg, Zn, P, D, Fe, and Zn. (Hossain et al. 2016) through a flame atomic absorption spectrophotometer (AA-7000, SHIMADZU). Nitrogen was measured through the Kjeldahl method which permits the available nitrogen in the plants (Gallaher et al. 1976).

2.4 Statistical Analysis

Data collected by the experiment were analyzed by Statistical software named Statistix. and the statistical significance was measured by the P value ≤ 0.05, and the means of treatments were compared with the least significant difference test (Steel et al. 1997).

Results showed that water stress reduced the morphological parameters such as shoot and root length in both the wheat varieties however the ZnO NPs seed priming significantly enhanced the morphological parameters such as shoot and root length when compared with untreated seeds. Seed priming with ZnO NPs significantly increased the shoot and root length (Table 1). Maximum shoot (69.34 cm) and root length (23.56 cm) were measured in Zincol-16 when the seed was primed with ZnO NPs at 120 ppm and grown under well-watered (100% FC) condition as compared to 160 ppm of ZnO NPs (64.05 cm shoot length and 21.76 cm root length) during seed priming. Similarly, seeds of Ujala-16 primed with 120 ppm of ZnO NPs and grown under 100% FC showed higher shoot (63.20 cm) and root length (21.47 cm) as compared to 160 ppm of ZnO NPs (58.95 cm shoot length and 20.04 cm root length). Zincol-16 was more responsive to ZnO NPs as compared to Ujala-16 whether grown under well-watered (100% FC) or water-stressed (50% FC) conditions. Wheat plants from untreated seeds resulted in a minimum shoot of 24.36 to 29.89 cm and root length of 8.27 to 10.15 cm in Ujala-16 and Zincole-16, respectively. Similarly, shoot and root fresh and dry weight increased significantly after seed priming with ZnO NPs. All the ZnO NPs treatments increased shoot and root dry weight as compared to untreated seeds. Maximum shoot fresh (13.26 g) and dry weight (5.45 g) was recorded in Zincol-16 when primed with ZnO NPs at 120 ppm and grown under well 100% FC followed by the same wheat variety at 160 ppm and Ujala-16 primed with 120 ppm of ZnO NPs. Water stress decreased the shoot fresh and dry weight but the maximum reduction in shoot fresh (4.66 g) and root dry weight (1.91 g) however was observed in Ujala-16 grown without seed treatment.

Table 1

Effect of ZnO NPs on shoot, root length, and shoot fresh and dry weight of wheat plants
Wheat varieties	Drought stress	ZnO levels	Shoot length (cm)	Root length (cm)	Shoot fresh weight (g)	Shoot dry weight (g)
Ujala-16	50% FC	Control	24.36 j	8.27 j	4.66 j	1.91 j
		40 ppm	35.74 h	12.14 h	6.83 h	2.80 h
		80 ppm	42.21 g	14.34 g	8.07 g	3.31 g
		120 ppm	52.77 e	17.93 e	10.09 e	4.14 e
		160 ppm	47.97 f	16.30 f	9.17 f	3.77 f
	100% FC	Control	40.69 g	13.83 g	7.78 g	3.19 g
		40 ppm	53.78 de	18.27 de	10.29 de	4.22 de
		80 ppm	54.67 de	18.57 de	10.46 de	4.29 de
		120 ppm	63.20 b	21.47 b	12.09 b	4.96 b
		160 ppm	58.98 c	20.04 c	11.28 c	4.63 c
Zincole-16	50% FC	Control	29.89 i	10.15 i	5.72 i	2.35 i
		40 ppm	40.39 g	13.73 g	7.73 g	3.17 g
		80 ppm	47.02 f	15.98 f	8.99 f	3.69 f
		120 ppm	55.74 d	18.94 d	10.66 d	4.38 d
		160 ppm	54.15 de	18.40 de	10.36 de	4.25 de
	100% FC	Control	46.88 f	15.93 f	8.97 f	3.68 f
		40 ppm	52.93 e	17.99 e	10.12 e	4.16 e
		80 ppm	58.84 c	19.99 c	11.26 c	4.62 c
		120 ppm	69.34 a	23.56 a	13.26 a	5.45 a
		160 ppm	64.05 b	21.76 b	12.25 b	5.03 b
LSD value at 5% probability level			2.25	0.76	0.43	0.17
Fc = Field capacity

Priming of wheat seed with ZnO NPs resulted in a higher leaf area of plants as compared to untreated seeds (Table 2). Water stress decreased the leaf area however; seed priming with ZnO NPs enhanced the leaf area. Zincol-16 wheat variety exhibited maximum leaf area (417 cm²) when seeds were primed with ZnO NPs (120 ppm) and sown under 100% FC as compared to Ujala-16 (318 cm²). After measuring leaf potential these represent a useful index of soil water stress by the wheat plant and provide insights into plant-water relationships. Data showed that wheat plants under drought stress showed higher leaf water potential. Plants grown from untreated seeds showed higher water potential. In plant leaf water potential, the improvement was shown after the treatment of ZnO NPs, and minimum leaf water potential (-24.00 bars) was recorded for Ujala-16 grown under well-watered conditions after seed priming with ZnO NPs at 160 ppm followed by Zincol-16 (-31.66 bars). Alike, relative water content (RWC) increased after seed priming with ZnO NPs (Table 2). Maximum RWC was observed for Zincol-16 (82.66%) after seed priming with ZnO NPs at 120 ppm and grown under well water conditions (100% FC) that was at par with Ujala-16 treated seeds with ZnO NPs at 160 ppm (82.00%). Both wheat varieties showed minimum RWC when seeds were not primed and grown in water stress conditions (50% FC) however the lowest RWC (62.66%) was noted for Zincol-16. Wheat plants showed higher content of Chl a, b, and total Chl content when seeds were primed with ZnO NPs. All the treatments of ZnO NPs improved Chl a, b, and total Chl over the plants grown from untreated seeds (Table 3). Water-stressed (50% FC) conditions reduced the Chl a, b, and total Chl as compared to well-watered conditions (100% FC). Maximum Chl a (1.69 mg/g FW), b (0.71 mg/g FW), and total Chl (2.46 mg/g FW) content was recorded for Zincol-16 when seeds were treated with ZnO NPs at 120 ppm and then planted under 100% FC (well watered) that was at par with Ujala-16 primed with ZnO NPs at 160 ppm. The lowest Chl a (1.33 mg/g FW), b (0.43 mg/g FW), and total Chl (1.76 mg/g FW) content was recorded for Zincol-16 when seeds were sown under drought-stressed conditions without ZnO treatment followed by Ujala-16. Untreated seeds of Ujala-16 planted under water stress conditions showed higher proline content however seed treatment with ZnO NPs also increased the proline content of wheat. Maximum proline content (5.13 µmoles g^− 1 FW) was recorded for Zincol-16 when seeds were primed with ZnO NPs at 120 ppm and grown under 50% FC level followed by Zincol-16 at 120 ppm (4.74 µmoles g^− 1 FW) and Ujala-16 seed treatment with ZnO NPs at 120 ppm (4.68 µmoles g^− 1 FW)grown under 50% FC. Alike, an antioxidant such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) ‎ascorbate peroxidase (APX) activity increased in plants when grown under drought stress conditions, and application of ZnO NPs also increased the antioxidants in wheat plants. However, maximum CAT (446.68 Units m^− 1 g^− 1 FW), SOD (617.08 Units m^− 1 g^− 1 FW), APX (2.68 ABA digested g^− 1 FW h^− 1), and GPx (165.66 Units m^− 1 g^− 1 FW) activity was recorded for Ujala-16 when grown with untreated under water stress conditions that were equal to Zincol-16 under the same set of experimental conditions. Seed treatment with ZnO NPs at 40 ppm showed higher antioxidant activity as compared to the higher doses of ZnO NPs. Similarly, water stress affected the nutrient concentration in wheat plants (Tables 5 and 6). Drought stress reduced the uptake of N, P, K, Ca, Mg, Zn, and Fe in plants when compared with well-watered plants. However, seed treatment with ZnO NPs significantly enhanced the uptake of N, K, and Zn while having less impact on P, Ca, Mg, and Fe. The Maximum concentrations of P (5.82 g kg^− 1 FW), K (16.31 g kg^− 1 FW), N (7.50 g kg^− 1 FW) Ca (19.39 mg kg^− 1 FW), Mg (2.80 mg kg^− 1 FW), Zn (25.32 mg kg^− 1 FW) and Fe (0.15 mg kg^− 1 FW) was recorded for Zincol-16 when seeded under well-watered conditions (100% FC) with 120 ppm ZnO NPs followed by Zincol-16 and Ujala-16 when seeds were primed with ZnO NPs at 160 and 120 ppm, respectively. In wheat seeds treated with a high concentration of ZnO NPs (160 ppm) the uptake of P, K, Ca, Mg, Zn and Fe decreased when compared with 120 ppm of ZnO NPs. Zincol-16 was found to be more responsive as compared to Ujala-16.

Table 2

Effect of ZnO NPs on root fresh and dry weight, leaf area and leaf water potential of wheat plants
Wheat varieties	Drought stress	ZnO levels	Root fresh weight (g)	Root dry weight (g)	Leaf area per plant (cm²)	Leaf water potential (bars)
Ujala-16	50% FC	Control	0.24 j	0.010 d	146 j	-77.66 b
		40 ppm	0.35 h	0.020 c	215 h	-72.00 c
		80 ppm	0.42 g	0.020 c	254 g	-68.33 d
		120 ppm	0.52 e	0.020 c	318 e	-62.33 g
		160 ppm	0.47 f	0.020 c	289 f	-46.66 ij
	100% FC	Control	0.40 g	0.020 c	245 g	-63.33 fg
		40 ppm	0.53 de	0.023 bc	323 de	-57.00 h
		80 ppm	0.54 de	0.026 ab	329 de	-48.66 i
		120 ppm	0.62 b	0.030 a	380 b	-40.00 k
		160 ppm	0.58 c	0.030 a	355 c	-24.00 m
Zincole-16	50% FC	Control	0.29 i	0.010 d	180 i	-86.33 a
		40 ppm	0.40 g	0.020 c	243 g	-79.00 b
		80 ppm	0.46 f	0.020 c	283 f	-71.66 c
		120 ppm	0.55 d	0.030 a	335 d	-63.66 fg
		160 ppm	0.53 de	0.026 ab	326 de	-55.00 h
	100% FC	Control	0.46 f	0.020 c	282 f	-67.33 de
		40 ppm	0.52 e	0.023 bc	319 e	-65.33 ef
		80 ppm	0.58 c	0.030 a	354 c	-55.33 h
		120 ppm	0.69 a	0.030 a	417 a	-46.00 j
		160 ppm	0.63 b	0.030 a	386 b	-31.66 l
LSD value at 5% probability level			0.023	0.004	13.60	2.48
Fc = Field capacity

Table 3

Effect of ZnO NPs on relative water content, chlorophyll a, b and total chlorophyll of wheat plants
Wheat varieties	Drought stress	ZnO levels	Relative water content (%)	Chlorophyll a (mg/g FW)	Chlorophyll b (mg/g FW)	Total chlorophyll (mg/g FW)
Ujala-16	50% FC	Control	63.66 g	1.35 g	0.44 f	1.79 i
		40 ppm	64.00 g	1.36 g	0.55 e	1.91 h
		80 ppm	77.66 e	1.65 e	0.66 c	2.31 d
		120 ppm	79.66 c	1.69 c	0.68 b	2.37 c
		160 ppm	79.66 c	1.69 c	0.68 b	2.37 c
	100% FC	Control	78.66 d	1.67 d	0.57 d	2.24 f
		40 ppm	79.66 c	1.69 c	0.68 b	2.37 c
		80 ppm	81.66 b	1.73 b	0.70 ab	2.43 b
		120 ppm	81.66 b	1.73 b	0.70 ab	2.43 b
		160 ppm	82.00 ab	1.74 ab	0.71 a	2.45 ab
Zincole-16	50% FC	Control	62.66 h	1.33 h	0.43 f	1.76 j
		40 ppm	68.66 f	1.46 f	0.59 d	2.04 g
		80 ppm	78.66 d	1.67 d	0.66 c	2.33 d
		120 ppm	78.66 d	1.67 d	0.65 c	2.32 d
		160 ppm	78.66 d	1.67 d	0.66 c	2.33 d
	100% FC	Control	79.66 c	1.69 c	0.58 d	2.27 e
		40 ppm	79.66 c	1.69 c	0.68 b	2.37 c
		80 ppm	79.66 c	1.69 c	0.68 b	2.37 c
		120 ppm	82.66 a	1.75 a	0.71 a	2.46 a
		160 ppm	79.66 c	1.69 c	0.68 b	2.37 c
LSD value at 5% probability level			0.74	0.014	0.019	0.029
Fc = Field capacity

Table 4

Effect of ZnO NPs on proline content and antioxidant activity of wheat plants
Wheat varieties	Drought stress	ZnO levels	Proline (µmoles g^− 1 FW)	CAT (Units m^− 1 g^− 1 FW)	SOD (Units m^− 1 g^− 1 FW)	APX (ABA digested g^− 1 FW h^− 1)
Ujala-16	50% FC	Control	1.80 j	446.68 a	617.08 a	2.68 a
		40 ppm	3.98 de	419.95 b	580.15 b	2.52 b
		80 ppm	4.05 de	382.47 c	528.38 c	2.29 c
		120 ppm	4.68 b	356.74 d	492.83 d	2.14 d
		160 ppm	4.37 c	197.59 n	272.97 n	1.18 n
	100% FC	Control	2.01 1	217.43 m	300.37 m	1.30 m
		40 ppm	2.64 h	229.32 l	316.80 l	1.37 l
		80 ppm	3.13 g	278.32 i	384.50 i	1.67 i
		120 ppm	3.91 e	301.31 g	416.26 g	1.81 g
		160 ppm	3.55 f	269.96 jk	372.95 jk	1.62 jk
Zincole-16	50% FC	Control	2.21 i	444.71 a	614.36 a	2.67 a
		40 ppm	3.92 e	418.93 b	578.74 b	2.51 b
		80 ppm	4.36 c	383.77 c	530.17 c	2.30 c
		120 ppm	5.13 a	346.81 e	479.11 e	2.08 e
		160 ppm	4.74 b	289.30 h	399.66 h	1.73 h
	100% FC	Control	3.47 f	212.43 m	293.47 m	1.27 m
		40 ppm	2.99 g	234.09 l	323.39 l	1.40 l
		80 ppm	3.48 f	268.57 k	371.03 k	1.61 k
		120 ppm	4.13 d	309.89 f	428.12 f	1.86 f
		160 ppm	4.01 de	276.56 ij	382.06 ij	1.66 ij
LSD value at 5% probability level			0.167	7.10	9.81	0.042
Fc = Field capacity

Table 5

Effect of ZnO NPs on glutathione peroxidase activity, nitrogen, phosphorus and potassium concentration in wheat plants
Wheat varieties	Drought stress	ZnO levels	Glutathione peroxidase (Units m^− 1 g^− 1 FW)	Nitrogen (g kg^− 1 FW)	Phosphorus (g kg^− 1 FW)	Potassium (g kg^− 1 FW)
Ujala-16	50% FC	Control	165.66 a	2.63 j	1.75 j	5.73 j
		40 ppm	155.74 b	3.86 h	2.03 h	8.41 h
		80 ppm	141.85 c	4.56 g	2.76 g	9.93 g
		120 ppm	132.30 d	5.71 e	3.96 e	12.42 e
		160 ppm	73.28 n	5.19 f	3.41 f	11.29 f
	100% FC	Control	80.64 m	4.40 g	2.59 g	9.58 g
		40 ppm	85.05 l	5.82 de	4.07 de	12.65 de
		80 ppm	103.22 i	5.91 de	4.17 de	12.86 de
		120 ppm	111.75 g	6.84 b	5.13 b	14.87 b
		160 ppm	100.12 jk	6.38 c	4.66 c	13.88 c
Zincole-16	50% FC	Control	164.93 a	3.23 i	1.37 i	7.03 i
		40 ppm	155.37 b	4.37 g	2.56 g	9.50 g
		80 ppm	142.33 c	5.09 f	3.31 f	11.06 f
		120 ppm	128.62 e	6.03 d	4.29 d	13.11 d
		160 ppm	107.29 h	5.86 de	4.11 de	12.74 de
	100% FC	Control	78.78 m	5.07 f	3.29 f	11.03 f
		40 ppm	86.81 l	5.73 e	3.97 e	12.45 e
		80 ppm	99.60 k	6.37 c	4.64 c	13.85 c
		120 ppm	114.93 f	7.50 a	5.82 a	16.31 a
		160 ppm	102.57 ij	6.93 b	5.22 b	15.07 b
LSD value at 5% probability level			2.63	0.24	0.25	0.53
Fc = Field capacity

Table 6

Effect of ZnO NPs on calcium, magnesium, iron and zinc concentration in wheat plants
Wheat varieties	Drought stress	ZnO levels	Ca (mg kg^− 1 FW)	Mg (mg kg^− 1 FW)	Fe (mg kg^− 1 FW)	Zn (mg kg^− 1 FW)
Ujala-16	50% FC	Control	6.81 j	0.98 j	0.21 a	8.90 j
		40 ppm	9.99 h	1.44 h	0.20 b	13.05 h
		80 ppm	11.80 g	1.70 g	0.18 c	15.42 g
		120 ppm	14.75 e	2.13 e	0.17 d	19.27 e
		160 ppm	13.41 f	1.93 f	0.09 k	17.52 f
	100% FC	Control	11.38 g	1.64 g	0.10 j	14.86 g
		40 ppm	15.04 de	2.17 de	0.11 i	19.64 de
		80 ppm	15.29 de	2.21 de	0.13 h	19.96 de
		120 ppm	17.67 b	2.55 b	0.14 g	23.08 b
		160 ppm	16.49 c	2.38 c	0.13 h	21.54 c
Zincole-16	50% FC	Control	8.36 i	1.20 i	0.21 a	10.92 i
		40 ppm	11.29 g	1.63 g	0.20 b	14.75 g
		80 ppm	13.15 f	1.89 f	0.18 c	17.17 f
		120 ppm	15.59 d	2.25 d	0.16 e	20.36 d
		160 ppm	15.14 de	2.19 de	0.13 g	19.78 de
	100% FC	Control	13.11 f	1.89 f	0.10 j	17.12 f
		40 ppm	14.80 e	2.14 e	0.11 i	19.33 e
		80 ppm	16.45 c	2.37 c	0.13 h	21.49 c
		120 ppm	19.39 a	2.80 a	0.15 f	25.32 a
		160 ppm	17.91 b	2.59 b	0.13 h	23.39 b
LSD value at 5% probability level			0.63	0.092	0.0031	0.82
Fc = Field capacity

Results showed that drought stress decreased the plant performance while seed priming with ZnO NPs enhanced the performance of plants not only in well water conditions but also under water stress conditions. This increase in shoot and root length, shoot and root fresh and dry seeds, and leaf area of plants grown from the seeds primed with ZnO NPs can be attributed due to the physiological and biochemical role of ZnO NPs in seed during priming and after germination (Samad et al., 2014; Hussain et al., 2014). However, When used as seed priming agents, ZnO NPs have varying effects on plant growth depending on the NP concentrations at which they are effective. (Elizabath et al., 2017). ZnO NPs can be more effective and correlate with the fact that in the biosynthesis of endogenous hormones the Zn shows a vital role. When the seed is primed with nanoparticles the hormones gibberellin and auxin increase the growth.

(Cakmak, 2008; Prasad et al., 2012). After the priming of seeds with ZnO NPs, better results show in seed synchronized germination and seedling establishment. (Broadley et al., 2007). It is possible to improve plant growth in the early stages of development by involving the Zn. (Ozturk et al., 2006). The result of this research suggested that show that the Zn Nanoparticles also showed an impact on plant physiology and growth because the seeds absorbed a greater capacity of NPs. The increase in plant shoots and root lengths, their fresh weight, and leaf area in plants grown from ZnO NPs primed seeds are presumably increased chlorophyll contents due to zinc involvement acting as a catalytic, structural component of proteins and enzyme, Co-factor for various developmental pigments biosynthesis process. (Hassan et al. 2020). Our results are to previous data by Tolay (2021) and Imtiaz et al. (2003). who documented that the application of Zn increased the plant's fresh, dry weight and height due to an increase in chlorophyll content and nutrient acquisition traits under normal. In Increasing the dry weight in wheat seedlings, the Zn shows an Effective role. Untreated seeds resulted in lower plant biomass and dry weight might be due to Zn deficiency. The result is similar to the research of Yilmaz et al. (1987) the plants treated with a low concentration of Zn can also show lower growth and seedling vigor. When increasing the Zn. The plant's growth also increased and they show improvement in the root and shoot growth. So, the seeds priming with ZnO also improve the quality and growth of the seeds with higher vigor.

Drought stress affected the leaf water potential and relative water content of wheat however seed treatment with ZnO NPs improved this parameter might be due to Zn helping the plants in a different physiological process. Such as stomatal regulation, photosynthesis and water use efficiency, cell membrane stability, and osmolyte accumulation. Thu the result is significant and shows better plant performance under the stress of water or well water condition (Hassan et al. 2020). The uptake of water by the plant's roots is reduced by the impact of drought stress due to this reduction in the crop production shown. The crop production is reduced by reducing the gas exchange rates, uptake of water, and leaf water status. (Farooq et al. 2017). Under drought stress relative water content (RWC) is reduced. Similar findings are depicted by Shemi et al. (2021) who documented that drought stress decreased the relative water content in maize leaves however, Zn application increased the RWC significantly. Reductions of leaf water potential are due to lower RWC reflect substantial, that cause stomata closing (Farooq et al. 2017; Hassan et al. 2020). Drought stress causes a significant reduction in chlorophyll content in wheat plants might be due to a reduction in reduced leaf, premature leaf senescence, increased leaf temperature, and impaired photosynthetic machinery (Bhargava and Sawant, 2013). However, ZnO NPs priming increased the chlorophyll content.

The result recorded showed that in the wheat plant the chlorophyll content increased from primed seed with ZnO NPs. That increases water uptake and nutrient uptake by the application of ZnO NPs due to this the growth of the leaf tends to be better and shows a positive effect in leaf area growth. The ZnO NPs increase the physiological performance and photosynthesis process. (Garcia-Gomez et al., 2017). The ZnO NPs show a vital role in the biosynthesis of chlorophyll by protecting the sulfhydryl group of the chlorophyll. (Cakmak, 2008). The ZnO NPs increase the chlorophyll content by participating in chloroplast development and functions in the repairing procedure of II Photosystem by a special protein called recycling damaged D1 protein. (Hansch and Mendel, 2009). The overall photosynthesis process and total chlorophyll content increase by the ZnO NPs. The overall biomass of plants is increased by the application of NPs of ZnO. (Latef et al., 2016). The above results are in agreement with the findings of Laware and Raskar (2014).

Proline content and antioxidants such as ‎ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD), activity increased in the plants grown under the drought stress conditions when compared with well-watered conditions.

However, under the well-watered and drought condition, the increases in proline and antioxidant content were noted by the seed priming with ZnO NPs. These are due to the Zn finger proteins. (Luo et al. 2012). ROS scavenging is enhanced by the C₂H₂ Zn finger protein. The C₂H₂ Zn finger protein boosts drought tolerance in plants. scavenging the ROS owing to increased activities of SOD and POD in rice by ZFP245 Zn finger protein. These reduced the drought stress in rice (Huang et al. 2009). In plat, the drought stress increased by C₂H₂ Zn finger protein. These protein increase and boost drought tolerance in the plant by using the signaling process and the hormone ABA. (Huang et al. 2009). Therefore, the increase in the expression of Zn finger proteins counters the effects of drought by increasing the accretion of compatible solutes, scavenging ROS, and affecting the signaling pathways. Drought stress decreased the uptake of N, P, K, Ca, Mg, Zn, and Fe in plants when compared with well-watered. Seed treatment with ZnO NPs considerably increased the uptake of N, K, and Zn as compared to P, Ca, Mg, and Fe might be due to the negative interaction because of interference of Mg, Fe, P, and Ca, in the Zn absorption on the surface of the root and its translocation from root to shoot in plants (Prasad et al., 2016). In short, drought stress decreased the wheat growth, and morphological parameters such as fresh and dry weight, chlorophyll content, and nutrients while seed priming with ZnO NPs improved the plant performance under both well-watered and drought stress.

The current study was performed to enhance the drought tolerance in both wheat varieties through seed priming with ZnO nanoparticles. Results showed that the leaf pigments decrease under drought stress conditions while improvements were observed where seed priming with ZnO nanoparticles was applied at the rate of 120ppm as compared to all their treatments. Similarly, the antioxidant activities, as well as the nutrient contents of wheat, were increased where ZnO nanoparticles were applied and showed better improvement under drought as well as normal conditions. Both wheat varieties showed better performance while the maximum improvement was noted in Zincole-16 as compared to Ujala-16 under normal as well as drought stress conditions where ZnO nanoparticles were primed. So the ZnO nanoparticles seed priming is useful tact for improving the performance as well as enhancing drought tolerance in wheat.

Author Contributions Conception and design were proposed by SFA and MAB and collected the data. SFA and ZA assembled the data and prepared the first draft of the manuscript. MASR and GHA finalized the final draft of the manuscript.

Funding No funding is available

Data Availability I declare that this article has not been submitted to any other journal and all the authors have agreed to submit the manuscript to ‘Acta Physiologiae Plantarum.’

Conflict of interest Authors has no conflict of interest in this article.

Consent for Publication I give my consent for the publication in ‘Acta Physiologiae Plantarum.’

Ahmad P, Alyemeni MN, Al-Huqail AA, Alqahtani MA, Wijaya L, Ashraf M, Bajguz A (2020) Zinc oxide nanoparticles application alleviates arsenic (As) toxicity in soybean plants by restricting the uptake of as and modulating key biochemical attributes, antioxidant enzymes, ascorbate-glutathione cycle, and glyoxalase system. Plants 9(7):825
Ali U (2020) Green Synthesis, Characterization & Therapeutic Evaluation of ZnO Nanoparticles Prepared Using Extract of Nigella sativa Seeds (Doctoral dissertation, CAPITAL UNIVERSITY)
Arnon DI (1949) Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta vulgaris. Plant Physiol 24(1):1
Barman H, Das SK, Roy A (2018) Zinc in soil environment for plant health and management strategy. Univers J Agric Res 6(5):149–154
Bates LS, Waldren RP, Teare ID (1973) Rapid determination of free proline for water-stress studies. Plant Soil 39(1):205–207
Bhargava S, Sawant K (2013) Drought stress adaptation: Metabolic adjustment and regulation of gene expression. Plant Breed 132:21–32
Cakmak I (2000) Tansley Review No. 111 Possible roles of zinc in protecting plant cells from damage by reactive oxygen species. New Phytol 146(2):185–205
Dixit V, Pandey V, Shyam R (2001) Differential antioxidative responses to cadmium in roots and leaves of pea (Pisum sativum L. cv. Azad). J Exp Bot 52(358):1101–1109
do Pereira ES, Caixeta Oliveira A, Fraceto HFernandes, Santaella C (2021) Nanotechnology potential in seed priming for sustainable agriculture. Nanomaterials 11(2):267
Farooq M, Hussain M, Habib MM, Khan MS, Ahmad I, Farooq S, Siddique KH (2020) Influence of seed priming techniques on grain yield and economic returns of bread wheat planted at different spacings. Crop and Pasture Science 71(8):725–738
Fincheira P, Tortella G, Seabra AB, Quiroz A, Diez MC, Rubilar O (2021) Nanotechnology advances for sustainable agriculture: current knowledge and prospects in plant growth modulation and nutrition. Planta 254(4):1–25
Gallaher RN, Weldon CO, Boswell FC (1976) A semiautomated procedure for total nitrogen in plant and soil samples. Soil Sci Soc Am J 40(6):887–889
Ghani MI, Saleem S, Rather SA, Rehmani MS, Alamri S, Rajput VD, Liu M (2022) Foliar application of zinc oxide nanoparticles: An effective strategy to mitigate drought stress in cucumber seedling by modulating antioxidant defense system and osmolytes accumulation. Chemosphere 289:133202
Hassan MU, Aamer M, Umer Chattha M, Haiying T, Shahzad B, Barbanti L, Guoqin H (2020) The critical role of zinc in plants facing the drought stress. Agriculture 10(9):396
He H, Wu M, Su R, Zhang Z, Chang C, Peng Q, Lambers H (2021) Strong phosphorus (P)-zinc (Zn) interactions in a calcareous soil-alfalfa system suggest that rational P fertilization should be considered for Zn biofortification on Zn-deficient soils and phytoremediation of Zn-contaminated soils. Plant Soil 461(1):119–134
Hossain SJ, Iftekharuzzaman M, Haque MA, Saha B, Moniruzzaman M, Rahman MM, Hossain H (2016) Nutrient compositions, antioxidant activity, and common phenolics of Sonneratia apetala (Buch.-Ham.) fruit. Int J Food Prop 19(5):1080–1092
Hosseinpour A, Haliloglu K, Tolga Cinisli K, Ozkan G, Ozturk HI, Pour-Aboughadareh A, Poczai P (2020) Application of zinc oxide nanoparticles and plant growth promoting bacteria reduces genetic impairment under salt stress in tomato (Solanum lycopersicum L.‘Linda’). Agriculture 10(11):521
Huang XY, Chao DY, Gao JP, Zhu MZ, Shi M, Lin HX (2009) A previously unknown zinc finger protein, DST, regulates drought and salt tolerance in rice via stomatal aperture control. Genes Dev 23:1805–1817
Itroutwar PD, Govindaraju K, Tamilselvan S, Kannan M, Raja K, Subramanian KS (2020) Seaweed-based biogenic ZnO nanoparticles for improving agro-morphological characteristics of rice (Oryza sativa L.). J Plant Growth Regul 39(2):717–728
Kaur H, Garg N (2021) Zinc toxicity in plants: a review. Planta 253(6):1–28
Luo X, Bai X, Zhu D, Li Y, Ji W, Cai H, Zhu Y (2012) GsZFP1, a new Cys2/His2-type zinc-finger protein, is a positive regulator of plant tolerance to cold and drought stress. Planta 235:1141–1155
Manivannan N, Aswathy S, Malaikozhundan B, Boopathi T (2021) Nano-zinc oxide synthesized using diazotrophic Azospirillum improves the growth of mung bean, Vigna radiata. Int Nano Lett 11(4):405–415
Pieczynski M, Marczewski W, Hennig J, Dolata J, Bielewicz D, Piontek P, Szweykowska-Kulinska Z (2013) Down‐regulation of CBP 80 gene expression as a strategy to engineer a drought‐tolerant potato. Plant Biotechnol J 11(4):459–469
Prasad R, Shivay YS, Kumar D (2016) Interactions of zinc with other nutrients in soils and plants-A Review. Indian J Fertilisers 12(5):16–26
Rai-Kalal P, Jajoo A (2021) Priming with zinc oxide nanoparticles improve germination and photosynthetic performance in wheat. Plant Physiol Biochem 160:341–351
Rajput VD, Singh A, Singh VK, Minkina TM, Sushkova S (2021) Impact of nanoparticles on soil resource. Nanomaterials for Soil Remediation. Elsevier, pp 65–85
Shang Y, Hasan MK, Ahammed GJ, Li M, Yin H, Zhou J (2019) Applications of nanotechnology in plant growth and crop protection: a review. Molecules 24(14):2558
Singla R, Kumari A, Yadav SK (2019) Impact of nanomaterials on plant physiology and functions. Nanomaterials and plant potential. Springer, Cham, pp 349–377
Steel RP, Rentsch JR (1997) The dispositional model of job attitudes revisited: Findings of a 10-year study. J Appl Psychol 82(6):873
Suganya A, Saravanan A, Manivannan N (2020) Role of zinc nutrition for increasing zinc availability, uptake, yield, and quality of maize (Zea mays L.) grains: An overview. Commun Soil Sci Plant Anal 51(15):2001–2021
Tabande L, Sepehri M, Yasrebi J, Zarei M, Ghasemi-Fasaei R, Khatabi B (2022) A comparison between the function of Serendipita indica and Sinorhizobium meliloti in modulating the toxicity of zinc oxide nanoparticles in alfalfa (Medicago sativa L.). Environ Sci Pollut Res 29(6):8790–8803
Tului V, Janmohammadi M, Abbasi A, Vahdati-Khajeh S, Nouraein M (2021) Influence of iron, zinc and bimetallic Zn-Fe nanoparticles on growth and biochemical characteristics in chickpea (Cicer arietinum) cultivars. Poljoprivreda i Sumarstvo 67(2):179–193
Usman M, Farooq M, Wakeel A, Nawaz A, Cheema SA, Rehman H, Sanaullah M (2020) Nanotechnology in agriculture: Current status, challenges and future opportunities. Science of the Total Environment, 721, 137778
Yao Y, Zhang T, Tang M (2022) A critical review of advances in reproductive toxicity of common nanomaterials to Caenorhabditis elegans and influencing factors.Environmental Pollution,119270
Zhang H, Xu Z, Guo K, Huo Y, He G, Sun H, Sun G (2020) Toxic effects of heavy metal Cd and Zn on chlorophyll, carotenoid metabolism and photosynthetic function in tobacco leaves revealed by physiological and proteomics analysis. Ecotoxicol Environ Saf 202:110856
Zhao L, Lu L, Wang A, Zhang H, Huang M, Wu H, Ji R (2020) Nano-biotechnology in agriculture: use of nanomaterials to promote plant growth and stress tolerance. J Agric Food Chem 68(7):1935–1947
Hassan U, Muhammad M, Aamer MU, Chattha T, Haiying B, Shahzad L, Barbanti M, Nawaz et al (2020) "The Crit role zinc plants facing drought stress " Agric 10(9):396
Tolay I (2021) The impact of different Zinc (Zn) levels on growth and nutrient uptake of Basil (Ocimum basilicum L.) grown under salinity stress.PLoS One, 16(2), e0246493
Shemi R, Wang R, Gheith ES, Hussain HA, Hussain S, Irfan M, Wang L (2021) Effects of salicylic acid, zinc and glycine betaine on morpho-physiological growth and yield of maize under drought stress. Sci Rep 11(1):1–14

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Seed nanopriming with zinc oxide improves wheat growth and photosynthetic performance in wheat under drought stress

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Abstract

1. Introduction

2. Materials And Methods

2.1 Agronomic and growth parameters

2.2 Physiological and biochemical parameters

2.3 Plant nutrient analysis

2.4 Statistical Analysis

3. Results

4. Discussion

Conclusion

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