Research Article

Drought Stress Mitigation in Wheat (Triticum aestivum L.) through Physiological Enhancements

Safdar Hussain1, Muhammad Naeem Mushtaq5, Ali Bakhsh3, Muhammad Mudassar Maqbool1, Muhammad Sarwar1, Muhammad Jan4*, Muhammad Abdul Qayyum2 and Arif Husain2

1Department of Agronomy, Ghazi University, Dera Ghazi Khan, Pakistan; 2Department of Soil and Environmental Sciences, Ghazi University, Dera Ghazi Khan, Pakistan; 3Department of Plant Breeding and Genetics, Ghazi University, Dera Ghazi Khan, Pakistan; 4Centre of Excellence for Olive Research and Training, Barani Agricultural Research Institute (BARI), Chakwal, Pakistan; 5Department of Agronomy, University of Agriculture Faisalabad, Pakistan.

Received | November 29, 2020; Accepted | March 21, 2021; Published | May 31, 2021

*Correspondence | Muhammad Jan, Centre of Excellence for Olive Research and Training, Barani Agricultural Research Institute (BARI), Chakwal, Pakistan; Email: [email protected]

Citation | Hussain, S., M.N. Mushtaq, A. Bakhsh, M.M. Maqbool, M. Sarwar, M. Jan, M.A. Qayyum and A. Husain. 2021. Drought stress mitigation in wheat (Triticum aestivum L.) through physiological enhancements. Pakistan Journal of Agricultural Research, 34(2): 424-430.

DOI | http://dx.doi.org/10.17582/journal.pjar/2021/34.2.424.430

Keywords | Moringa leaf water extract, Mulberry leaf water extract, Salicylic acid, Abscisic acid, Drought

Introduction

There are about 1.2 billion poor who consume wheat as the main staple in their diet, and 2.5 billion wheat-consuming poor, living predominantly in Africa and Asia. Worldwide, more land is used to grow wheat than any other crop. Wheat is the second most important cereal for direct human consumption (rather than for livestock feed) and the most significant global source of non-animal protein. Around half of calories consumed in North Africa and West and Central Asia are from wheat. In order to meet future, demand the average annual increase in global wheat yield must jump from its current level of below 1 percent to at least 1.6 percent (Eskola et al., 2020). In Pakistan, wheat grain considered as main staple food (60% of caloric intake in daily diet) for a common person. It was cultivated on area of 9052,000 hectares, having production of about 25.75 million tonnes (Masood, 2015).

Wheat possesses a vital position in Pakistan’s financial system to reduce the gap between food productions and consumption, therefore crucial for national food security (Alam et al., 2008). Rainfed areas are included in the major wheat-producing regions of Pakistan. However, wheat production in rainfed areas is around 50% of the irrigated areas. One of the main targets of Pakistan’s national wheat breeding programs is an enhancement of drought resistance in wheat cultivars. Although breeders have successfully increased wheat yield at the national level, they have achieved limited success in agro-ecological zone where natural conditions are very uncertain and various stresses occur including drought, heat and salt (Agarwal et al., 2005). In case of wheat crop, genotypic performance evaluation is an important index for screening the drought tolerance under drought. Pre-anthesis and at anthesis stage, deficiency of water can cause a reduction in several spikes and quantity of grains per spike (Samarah et al., 2009; Chai et al., 2016). Among the growth parameters mostly effective yield attributes are grain weight and grain per spike. Wheat growth period from stem elongation to heading and heading to milking reported being more susceptible to a shortage of water stress (Gupta et al., 2002; Zhang et al., 2017).

Growth regulators like abscisic acid (ABA) play a key role in improving drought tolerance of field crops. Abscisic acid synthesizes under drought conditions and sent a signal to guard cell which results in the closure of stomata, which maintains the water balance of the cell, and improves the turgidity under stress conditions. ABA application under drought stress improved drought tolerance by conserving plant cell moisture and improving/maintaining plant growth (Hussain et al., 2010, 2012). Among the plant growth hormones, salicyclic acid is considered as an important hormone which promoted plant photosynthetic rates, production of plant biomass and crop leaf area (Fahad et al., 2017). It was noted that application of salicyclic acid increases the wheat resistance against osmotic stress caused by water deficit conditions (Fahad et al., 2015; Ahmad et al., 2019; Khan et al., 2019).

It was reported from the previous research that drought stress actually reduces cytokinin contents, which effect the produce yield and quality (Shahid et al., 2017). Leaf of moringa consist of different vitamins, growth regulators, anti-oxidants and essential nutrients (Foidl et al., 2002; Yasmeen et al., 2013). Abscissic acid, SA and MBLE are mostly being applied as growth stimulants used as foliar application as well as priming of seed of cereals. Biostimulants actually modify the plant growth by changing in metabolic process under different stresses (Yasmeen et al., 2013; Khan et al., 2017).

Application of plant water extracts like rice, wheat, sorghum, mulberry and moringa in low concentration under drought stress can also improve the drought tolerance in wheat genotypes. The leaf sap of moringa is a source of hormones and nutrients especially like zeatin and ascorbate, K+, Ca+ and Fe+ (Makkar and Becker, 1996). It increased yield as it is enhances roots and enhance productivity upto 20-35% (Fuglie, 2001). Leaf extract of Mulberry is a rich source of anti-oxidant enzymes which prevent, stabilize and terminate the reactive oxygen species (ROS) production and protect cell from higher photo transpiration in chloroplast under abiotic stresses like salinity and drought stress (Haq et al., 2010). From the above positive and beneficial response of ABA, SA, moringa leaf extracts and mulberry leaf extracts it is imperative to investigate the drought stress impact on agronomic and yield attributes of wheat genotypes and compare the response of plant growth regulators on wheat growth under drought stress.

Materials and Methods

The research trial was held at research area of Ghazi University, Dera Ghazi Khan, Pakistan. Wheat genotypes were sown in line at 22 cm at field capacity after preparing the seedbed with one plowing and two cultivation and each cultivation followed by planking. One bag of urea, Di ammonium Phosphate (DAP) and Sulphate of Potash (SOP) were applied. All DAP, SOP and one bag of urea per acre were applied at first irrigation (25 days after sowing). After the first irrigation 250 g Logron extra per acre was applied to control the broad leaf weeds. Wheat genotypes (Triple dwarf-1, Aas-2011, and Faisalabad- 2008) were exposed to critical drought stage i.e. skipping irrigation at terminal stage (grain filling). The plants were exposed to normal irrigation, skipping irrigation with 2µM ABA, 10 mM SA, 15% MLE and 10% MBLE were applied at grain filling stage but skipping irrigation. The trial was designed accordingly to randomized complete block design (RCBD) with the factorial arrangement. Each treatment was repeated thrice. The growth and yield attributes of different genotypes were studied statistically by using RCBD factorial. The grain protein contents (mg/g) were estimated by the Kjeldahl method (Magomya et al., 2014). Water use efficiency (WUE) and Relative leaf water content (RWC) was computed by the formula given by (Sairam et al., 2002).

WUE%= grain yield (kg ha1) / water use (mm)

RWC%= Fresh weight – dry weight/turgid weight - dry weight × 100

Soil moisture contents (%) measured after an interval of seven days treatments application. Data regarding studied parameters were statistically analyzed. Treatment means were compared at 5% level of significance.

Results and Discussion

Plant population is a single utmost factor contributing to the final crop yield. The impact of treatments and wheat genotypes was statistically non-significant on several plants m-2 (Table 1). There was a significant differences among treatments and genotypes means regarding yield related attributes such as number of plant m-2, spike length (cm), plant height (cm), number of tillers, spike, yield parameters, harvest index (%) and biological yield (Tables 1 and 2). Data for varieties showed, Aas-2011 performed well for yield related parameters as compared to other wheat cultivar Faisalaabad-2008 and TD-1. The maximum value for yield attributes were noted in T1 (full irrigations) followed by T2, T3 and T4 while minimum was noted in T5 where 10% MBLE was applied to three wheat genotypes at grain filling stage after skipping irrigation. Moreover, maximum grain yield (5873.33kg ha-1) and biological yield (16525.14 kg ha-1) were noted in T1 and minimum grain yield (5130.34kg ha-1) and minimum biological yield (16177.13 kg ha-1) were found in T5. Maximum harvest index of 35.35 % was noted in T1 and minimum (31.93 %) was calculated in T5 (Table 2).

Spikelet’s spike-1 contributed positively to grain yield. The spike with more spikelet’s contributed more for the grain yield. So, the cultivar selection having more spikelet’s spike-1 ultimately results into better yielding lines (Tables 1 and 2). Thousand grain weight, length and reduced under drought stress while by applying ABA, SA and MLWE counter the impact of water shortage by improving yield and yield contributing parameters (Tables 1 and 2).

ABA application partially closes the stomata and conserves the plant moisture which ultimately improved the performance of wheat genotypes (Haq et al., 2010; Ahmad et al., 2014). The salicylic acid application also improved leaf area, rate of photosynthesis and production of plant dry matter. Moreover, it also induced plant security against pathogens (Ahmad et al., 2014). Salicyclic acid results into closure of stomata, chlorophyll contents and

 

Table 1: Impact of drought management strategies on growth and yield of wheat genotypes.

Treatments	Plants m-2	Plant height (cm)	Tillers m-2	Spikes m-2	Spikelets spike-1		Grains spike-1	Spike length (cm)	1000-grain weight (g)
Drought management strategies
T1=full irrigations, no ABA, SA, MLE and MBLE	98.68 A	90.44 A	297.81 A	287.72 A	20.07 A	57.55 A		13.36 A	43.55 A
T2=2µM ABA (- GF)	95.55 A	88.77 B	287.17AB	284.83 B	18.56 B	55.21 B		12.38 B	40.95 B
T3=10mM SA (- GF)	93.38 A	86.55 C	278.03 C	279.91 C	14.42 D	48.49 D		9.24 D	38.94 D
T4=15% MLE	94.61 A	88.11 BC	287 AB	276.87 D	17.82 C	51.88 C		11.17 C	40.76 C
T5=10% MBLE (- GF)	92.46 A	84.33 D	276.82 D	273.82 E	13.68 E	45.82 E		8 .59 E	37.75 E
LSD (0.5)		0.79	0.68	0.23	0.41	0.28		0.22	0.31
Wheat cultivars
Aas-2011	96.99 A	91 A	292.20 A	283.62 A	18.89 A		54.05 A	12.12 A	42.54 A
Faisalabad-2008	95.46 A	87.46 B	285.63AB	280.91 B	16.11B		52.20 B	11 .35 B	40.56 B
TD-1	93.47 A	84.46 C	278.72 C	277.36 C	14 C		49.11 C	9.38 C	38.06 C
LSD (0.5)		0.38	0.33	2.89	0.20		0.14	0.10	0.15

Means sharing the same letter within the column and rows differ non-significantly at the 5% probability level. ABA: abscisic acid; SA: salicyclic acid; MLE: Moringa leaf water extract; MBLE: mulbery leaf water extract; (- GF), skipping irrigation at grain filling stage.

 

Table 2: Impact of drought management strategies on growth, yield and water relations of wheat genotypes.

Treatments	Grain yield (kg ha-1)	Biological yield (kg ha-1)	Harvest Index %		WUE (kg ha-1 mm-1)	Drought yield index (%)	Protein contents (mg g-1)	Leaf water contents (%)	Soil moisture contents (%)
Drought management strategies
T1=full irrigations, no ABA, SA, MLE and MBLE	5873.3 A	16612.6 A		35.3 A	6.18 A	100 A	19.41 A	75.14 A	16.27 A
T2=2µM ABA (- GF)	5708.51B	16380.9 B		34.85 B	4.78 B	92.21B	17.37 B	72.65 B	14.40 B
T3=10mM SA (- GF)	5391.59C	16284.5 D		33.17 C	4.33 C	91.78 C	14.50 C	72.41 C	13.92 C
T4=15% MLE	5287.10D	16188.3 C		32.63D	4.51 D	89.95 D	14.24D	69.23 D	13.21 D
T5=10% MBLE (- GF)	5130.34F	16059.3 E		31.93 E	3.81E	87.31 E	13.55 E	68.53 E	13.04 E
LSD (0.5)	0.41	0.21		0.71	0.65	0.71	0.22	0.78	0.67
Wheat cultivars
Aas-2011	5711.24 A	16525.1 A	34.55 A		5.53 A	93.51 A	16.64 A	73.15 A	14.84A
Faisalabad-2008	5524.76 B	16213.2 B	34.09 B		4.39 B	93.43 B	15.26 B	72.24 B	14.22 B
TD-1	5198.55 C	16176 C	32.12 C		4.25 C	92.81 C	14.8 C	70 .39 C	13.45 C
LSD (0.05)	0.21	0.25	0.54		0.33	0.39	0.10	0.55	0.35

Means sharing the same letter within the column and rows differ non-significantly at the 5% probability level. ABA: abscisic acid; SA: salicyclic acid; MLE: Moringa leaf water extract; MBLE: mulbery leaf water extract; (- GF), skipping irrigation at grain filling stage; WUE: water use efficiency.

 

water use efficiency improvement, inter cellular concentration of carbon dioxide, respiratory-pathways and biochemical attributes (Rady et al., 2013; Ali et al. 2013). Mulbery leaf water extract application to wheat genotypes under drought conditions improved yield and yield components. It was observed by many researchers that under drought stress, 30 times diluted moringa leaf extract is beneficial for the growth of plant (Wajid et al., 2002; Yasmeen et al., 2013). This increase in yield and its components might be because of moringa leaf extract which is enriched with significant concentrations of essential nutrients (potassium and calcium), plant hormones (cytokinin, ascorbates, phenols) and zeatin (Afzal et al., 2008; Basra et al., 2009; Khan et al., 2017).

The impact of treatments on the plant population of wheat cultivars was nonsignificant (Table 1). It was due to the use of the same seed rate, planting geometry and other inputs that maintain the same plant population (Wajid et al., 2002). The use of bio stimulants significantly affected the plant height. The genotypic variation among the wheat cultivars is an important index of drought tolerance. This variation in genetic makeup of studied cultivars clarified that Aas-2011 is taller, Faisalabad-2008 is a medium and TD-1 is a dwarf cultivar. These results support the findings of an earlier report (Fahad et al., 2017) which indicated that genotypic variation among wheat cultivars contributed to drought tolerance. Similar findings were also observed by Ashraf et al. (2017) as they reported significant genotypic variation in plant height of wheat, oat and barley. Aas-2011 cultivar showed higher potential to produce tillers per plant as compare to Faisalabad-2008 and TD-1 (Table 1). This might be genetic variation of Aas-2011 plant to conserve more water under the limited availability of moisture. Water conservation in plant body under drought is an important index to differentiate between drought-sensitive and drought-resistant cultivars of field crops (Anjum et al., 2016; Hussain et al., 2012; Jena et al., 2017; Fahad et al., 2017).

Treatments and wheat cultivars had significant impact on plant physiological attributes such as crop relative water contents, WUE and maximum drought yield index of wheat genotypes (Table 2). T1 showed the maximum values of WUE (6.18 Kg ha-1 mm-1), RWC (75.14 %) and drought yield index (87.31%) as compared to others treatments. Protein contents and soil moisture contents of wheat genotypes were affected by divergent treatments (Table 2). Maximum Protein contents (19.41 mg/g) and soil moisture contents (16.27 %) were noted in T1 and minimum protein contents 13.55 (mg/g) and soil moisture contents (13.45 %) were estimated in T5 (Table 2). Data for varieties showed that the maximum Protein contents, soil moisture contents WUE, RWC and drought yield index were found in Aas-2011 (Table 2). Similar results were also observed by some other researchers as they reported that the application of bio stimulants like ABA, MBLE and SA have a significant impact on biochemical and physiological attributes (Foidl et al., 2002; Abdalla, 2013; Mona, 2013).

Conclusion and Recommendations

The application of Abscisic acid, moringa leaf extract and salicylic acid had pronounced impact on wheat growth, and yield. It is concluded that exogenous application 2µM ABA to wheat genotype AAS-11 after skipping irrigation at grain filling stage produced maximum yield. This increase in yield was due to improving drought tolerance of wheat genotype as ABA helps the plant in water conservation. The foliar application of growth regulators with plant water extracts increased the yield and yield related attributes of Aas-2011 under water stressed conditions. Use of bio-stimulants as foliar and seed priming reduced the stress impact. On the base of current study results, it is recommended to use these bio-stimulants in blended form with fertilizers for a profitable yield.

Acknowledgments

The author wishes to thank Professor Dr. Muhammad Iqbal Ghazi University, Dera Ghazi Khan-32200, Pakistan for the critical review of the manuscript.

Novelty Statement

The current scenario of water shortage, increasing population and more food demand enforcing the researchers to search alternate shortgun approaches to get a productive crop yield. The application of growth regulators is also an aspect of such approaches, which are helpful to improve the plant growth under drought conditions.

Author’s Contribution

Safdar Hussain: Designed and collected data.

Muhammad Naeem Mushtaq: Analyzed the data.

Ali Bakhsh and Muhammad Mudassar Maqbool: Designed this experiment.

Muhammad Sarwar and Muhammad Jan: Prepared the first draft of the article.

Safdar Hussain also finalized the draft after a careful reading of Muhammad Abdul Qayyum and Arif Hussain.

Conflict of interest

The authors have declared no conflict of interest.

References

Abdalla, M.M., 2013. The potential of Moringa oleifera extract as a biostimulant in enhancing the growth, biochemical and hormonal contents in rocket (Eruca vesicaria subsp. sativa) plants. Int. J. Plant Physiol. Biochem., 5: 42–49. https://doi.org/10.5897/IJPPB2012.026

Afzal, I., B. Hussain, S.M.A. Basra and H. Rehman. 2012. Priming with moringa leaf extract reduces imbibitional chilling injury in spring maize. Seed Sci. Technol., 40: 271–276. https://doi.org/10.15258/sst.2012.40.2.13

Afzal, I., S. Rauf, S.M.A. Basra and G. Murtaza. 2008. Halopriming improves vigor, metabolism of reserves and ionic content in wheat seedling under salt stress. Plant Soil Environ., 4: 382–388. https://doi.org/10.17221/408-PSE

Agarwal, S., R.K. Sairam, G.C. Srivastava and R.C. Meena. 2005. Changes in antioxidant enzymes activity and oxidative stress by abscisic acid and salicylic acid in wheat genotypes. Biol. Plant, 49(4): 541-550. https://doi.org/10.1007/s10535-005-0048-z

Ahanger, M.A., N.M. Talab, E.F. Abd-Allah, P. Ahmad and R. Hajiboland. 2016. Plant growth under drought stress: Significance of mineral nutrients. Water stress and crop plants: A sustainable approach, 2. https://doi.org/10.1002/9781119054450.ch37

Ahmad, S., M. Kamran, R. Ding, X. Meng, H. Wang, I. Ahmad, S. Fahad and Q. Han. 2019. Exogenous melatonin confers drought stress by promoting plant growth, photosynthetic capacity and antioxidant defense system of maize seedlings. PeerJ., 7: e7793. https://doi.org/10.7717/peerj.7793

Ahmad, I., S.M.A. Basra and A. Wahid. 2014. Exogenous application of ascorbic acid, salicylic acid and hydrogen peroxide improves the productivity of hybrid maize at low temperature stress. Int. J. Agric. Biol., 16: 825–830.

Ahmad, M., Z. Akram, M. Munir and M. Rauf. 2006. Physio-morphic response of wheat genotypes under rainfed conditions. Pak. J. Bot., 38(5): 1697-1702.

Alam, M.S., A.H.M.M. Rahman, M.N. Nesa, S.K. Khan and N.A. Siddquie. 2008. Effect of source and/or sink restriction on the grain yield in wheat. J. Appl. Sci. Res., 4(3): 258-261.

Ali, A., M. Tahir, M. Amin, S.M.A. Basra, M. Maqbool and D. Lee. 2013. Si induced stress tolerance in wheat (Triticum aestivum L.) hydroponically grown under water deficit conditions. Bulg. J. Agric. Sci., 19(5): 951-957.

Ashraf, R., M. Ahmed and G. Shabbir. 2017. Wheat physiological response under drought. In: Quantification of climate variability, adaptation and mitigation for agricultural sustainability. Springer, Cham. pp. 211-231. https://doi.org/10.1007/978-3-319-32059-5_10

Anjum, S. A., M. Tanveer, S. Hussain, S.A. Tung, R.A. Samad, L. Wang and B. Shahzad. 2016. Exogenously applied methyl jasmonate improves the drought tolerance in wheat imposed at early and late developmental stages. Acta Physiol. Planta., 38(1), 25.

Basra, S.M.A., M. Zahar, H. Rehman, A. Yasmin and H. Munir. 2009. Evaluating the response of sorghum and moringa leaf water extracts on seedling growth in hybrid maize. In: Proceedings of the international conference on sustainable food grain production: Challenges and opportunities. University of Agriculture, Faisalabad, Pakistan. pp. 22.

Chai, Q., Y. Gan, C. Zhao, H.L. Xu, R.M. Waskom, Y. Niu and K.H. Siddique. 2016. Regulated deficit irrigation for crop production under drought stress. A review. Agron. Sustain. Dev., 36(1): 3. https://doi.org/10.1007/s13593-015-0338-6

Eskola, M., G. Kos, C.T. Elliott, J. Hajslova, S. Mayar and R. Krska. 2020. Worldwide contamination of food-crops with mycotoxins: Validity of the widely cited FAO estimate of 25%. Crit. Rev. Food Sci. Nutr., 60(16): 2773-2789. https://doi.org/10.1080/10408398.2019.1658570

Fahad, S., A.A. Bajwa, U. Nazir, S.A. Anjum, A. Farooq, A. Zohaib, S. Sadia, W. Nasim, S. Adkins, S. Saud, M.Z. Ihsan, H. Alharby, C. Wu, D. Wang and J. Huang. 2017. Crop production under drought and heat stress: Plant responses and Management Options. Front Plant Sci., 8: 1147. https://doi.org/10.3389/fpls.2017.01147

Fahad, S., L. Nie, Y. Chen, C. Wu, D. Xiong, S. Saud, L. Hongyan, K. Cui and J. Huang. 2015. Crop plant hormones and environmental stress. Sustain Agric. Rev., 15: 371–400. https://doi.org/10.1007/978-3-319-09132-7_10

Fahad, S., A.A. Bajwa, U. Nazir, S.A. Anjum, A. Farooq, A. Zohaib and M.Z. Ihsan. 2017. Crop production under drought and heat stress: plant responses and management options. Front. Plant Sci., 8: 1147. https://doi.org/10.3389/fpls.2017.01147

Foidl, N., H.P.S, Makkar and K. Becker. 2002. The potential of Moringa oleifera for agricultural and industrial uses. In: World Church Service, Proceedings of the International Seminar on Moringa Oleifera, Dar es Salaam, April 2002, p. 29.

Fuglie, L.J., 2001. Combating malnutrition with Moringa. The miracle tree: The multiple attributes of Moringa.(Ed. J. Lowell Fuglie). CTA Publication, Wageningen, 117.

Gupta, N.K., S.K. Meena, S. Gupta and S.K. Khandelwal. 2002. Gas exchange, membrane permeability, and ion uptake in two species of Indian jujube differing in salt tolerance. Photosynth, 40(4): 535-539. https://doi.org/10.1023/A:1024343817290

Halmer, P., 2004. Methods to improve seed performance in the field. Handb. Seed Physiol., pp. 125-165.

Haq, R.A., M. Hussain, Z.A. Cheema, M.N. Mushtaq and M. Farooq. 2010. Mulberry leaf water extract inhibits bermudagrass and promotes wheat growth. Weed Biol. Manage., 10(4): 234-240. https://doi.org/10.1111/j.1445-6664.2010.00389.x

Hussain, S., B.L. Ma, M.F. Saleem, S.A. Anjum, A. Saeed and J. Iqbal. 2012. Abscisic acid spray on sunflower acts differently under drought and irrigation conditions. Agron. J., 104(3): 561-568.

Hussain, S., M.F. Saleem, M.Y. Ashraf, M.A. Cheema and M.A. Haq. 2010. Abscisic acid, a stress hormone helps in improving water relations and yield of sunflower (Helianthus annuus L.) hybrids under drought. Pak. J. Bot., 42(3): 2177-2189.

Jena, A., R.K. Sing and M.K. Sing. 2017. Mitigation measures for wheat production under heat stress condition. Int. J. Agric. Sci. Res., 7: 359–337.

Khan, S., S.M.A. Basra and M. Nawaz. 2019. Combined application of moringa leaf extract and chemical growth-promoters enhances the plant growth. South Afr. J. Bot., https://doi.org/10.1016/j.sajb.2019.01.007

Khan, S., S.M.A. Basra, I. Afzal and A. Wahid. 2017. Screening of moringa landraces for leaf extract as biostimulant in wheat. Int. J. Agric. Biol., 19: 999–1006. https://doi.org/10.17957/IJAB/15.0372

Khan, W., B. Prithiviraj and D.L. Smith. 2003. Photosynthetic responses of corn and soybean to foliar application of salicylates. J. Plant Physiol., 160(5): 485-492. https://doi.org/10.1078/0176-1617-00865

Magomya, A.M., D. Kubmarawa, J.A. Ndahi and G.G. Yebpella. 2014. Determination of plant proteins via the Kjeldahl method and amino acid analysis: A comparative study. Int. J. Sci. Technol. Res., 3(4): 68-72.

Makkar, H.A. and K. Becker. 1996. Nutrional value and antinutritional components of whole and ethanol extracted Moringa oleifera leaves. Anim. Feed Sci. Technol., 63(1-4): 211-228. https://doi.org/10.1016/S0377-8401(96)01023-1

Makkar, H.P.S., G. Francis and K. Becker. 2007. Bioactivity of phytochemicals in some lesser-known plants and their effects and potential applications in livestock and aquaculture production systems. Animal, 1(9): 1371-1391. https://doi.org/10.1017/S1751731107000298

Masood, M.S., 2015. Wheat in Pakistan, a status paper. National Coordinator Wheat Plant Sciences Division, Pakistan Agricultural Research Council, Islamabad, Pakistan, pp. 1–9.

Mona, M.A., 2013. The potential of Moringa oleifera extract as a biostimulant in enhancing the growth, biochemical and hormonal contents in rocket (Eruca vesicaria subsp. sativa) plants. Int. J. Plant Physiol. Biochem., 5: 42–49. https://doi.org/10.5897/IJPPB2012.026

Qadir, M., A. Sultan, H. Khan, A.S. Khan, A.M. Kazi and S.M.A. Basra. 2014. Identification of QTLs for drought tolerance traits on wheat chromosome 2A using association mapping. Int. J. Agric. Biol., 16(5).

Raddy, M.A., B.C. Varma and S.M. Howladar. 2013. Common bean (Phaseolus vulgaris L.) seedlings overcome NaCl stress as a result of presoaking in Moringa oleifera leaf extract. Sci. Hortic., 162: 63–70. https://doi.org/10.1016/j.scienta.2013.07.046

Reddy, A.R., K.V. Chaitanya and M. Vivekanandan. 2004. Drought induced responses of photosynthesis and antioxidant metabolism in higher plants. J. Plant Physiol., 161: 1189–1202. https://doi.org/10.1016/j.jplph.2004.01.013

Sairam, R.K., K.V. Rao and G.C. Srivastava. 2002. Differential response of wheat genotypes to long term salinity stress in relation to oxidative stress, antioxidant activity and osmolyte concentration. Plant Sci. 163:1037-1046.

Samarah, N.H., A.M. Alqudah, J.A. Amayreh and G.M. McAndrews. 2009. The effect of late-terminal drought stress on yield components of four barley cultivars. J. Agron. Crop Sci., 195(6): 427-441. https://doi.org/10.1111/j.1439-037X.2009.00387.x

Singh, B. and K. Usha. 2003. Salicylic acid induced physiological and biochemical changes in wheat seedlings under water stress. Plant Growth Regul., 39(2): 137-141. https://doi.org/10.1023/A:1022556103536

Shahid, M., Saleem, M.F., Anjum, S.A and I. Afzal. 2017. Biochemical markers assisted screening of Pakistani wheat (Triticum aestivum L.) cultivars for terminal heat stress tolerance. Pak. J. Agri. Sci. 54(4).

Suzuki, N., R.M. Rivero, V. Shulaev, E. Blumwald and R. Mittler. 2014. Abiotic and biotic stress combinations. New Phytol., 203(1): 32-43. https://doi.org/10.1111/nph.12797

Wajid, A., A. Hussain, M. Maqsood, A. Ahmad and M. Awais. 2002. Influence of sowing date and irrigation levels on growth and grain yield of wheat. Pak. J. Agric. Sci., 39(1): 22-24.

World Agricultural Outlook Board. 2014. World Agricultural Supply and Demand Estimates. WASDE-530. USDA-ERS, FAS (online). http://www.usda.gov/oce/commodity/wasde/latest.pdf

Yasmeen, A., S.M.A. Basra, M. Farooq, H. Rehman, N. Hussain and H.R. Athar. 2013. Exogenous application of moringa leaf extract modulates the antioxidant enzyme system to improve wheat performance under saline conditions. Plant Growth Regulat., 69: 225–233. https://doi.org/10.1007/s10725-012-9764-5

Zhang, H. and T. Oweis. 1999. Water–yield relations and optimal irrigation scheduling of wheat in the Mediterranean region. Agric. Water Manage., 38(3): 195-211. https://doi.org/10.1016/S0378-3774(98)00069-9

Zhang, X., W. Qin, S. Chen, L. Shao and H. Sun. 2017. Responses of yield and WUE of winter wheat to water stress during the past three decades. A case study in the North China Plain. Agric. Water Manage., 179: 47–54. https://doi.org/10.1016/j.agwat.2016.05.004