THE FOLIAR APPLICATION OF NITROGEN AND ZINC APPLIED DURING TILLERING AND BOOTING STAGE ENHANCED THE GROWTH AND PRODUCTION OF WHEAT ( TRITICUM AESTIVUM L.)

Foliar application of nitrogen and zinc has proven beneficial to achieve high yield and growth of wheat. A field trial was conducted with Randomized Complete Block Design (RCBD) in three replications, at Student’s Experiment Farm, Department of Agronomy, Sindh Agriculture University, Tandojam during spring 2022-2023. The study explored the effect of foliar application of nitrogen (N) and zinc (Zn) on wheat ( Triticum sativum L.) variety TD-1 on different growth stages. The treatment comprised T 1 = Control, T 2 = 2.0% N (tillering), T 3 = 2.0% N (booting), T 4 = 0.1% Zn (tillering), T 5 = 0.1% Zn (booting), T 6 = 2.0% N + 0.1% Zn (tillering), and T 7 = 2.0% N + 0.1% Zn (booting). The results revealed that all the parameters were significantly affected (p <0.05) by foliar applications of N and Zn at both tillering and booting stages. The highest growth and yield traits were recorded when the plants were treated with 2.0 % N + 0.1% Zn applied (foliar) at tillering stage. However, the plants grown under control conditions exhibited lower performance for all the traits recorded. In conclusion, the interaction of 2.0% N + 0.1% Zn with foliar spray demonstrated positive response towards wheat variety TD-1 at tillering stage as compared to other treatments. Hence, the combined strategy of applying foliar nitrogen and zinc at tillering stage is recommended to get higher grain yields and plant growth for chaff production.


INTRODUCTION
Wheat (Triticum sativum L.) is an annual, selfpollinated, allohexaploid (Khan et al., 2023) monocotyledon and an earliest planted cereal crop belonging to the family Poaceae (Saleem et al., 2023).Due to its momentous longevity and nutritive quality, it is deemed the "king of cereals" (Khan et al., 2023).It contains huge amounts of protein, carbohydrates, vital nutrients, and dietary fibers (Kumar et al., 2022).Wheat is one of the most widely cultivated staple food grains across the globe including Pakistan and the second most important crop in the world after rice (Majeed et al., 2023).
The annual production of wheat was recorded about 27.63 million tons cultivated on the area of about 9 million hectares in 2022-23.The production was increased about 5.4% as compared to the fiscal year 2021-22 (GoP, 2023)).As Pakistan is included among the most populous countries, its population mostly depends on wheat, used as a staple food for meeting dietary needs (Ijaz et al., 2023).It is estimated that by 2050, Pakistan is set to rank 6 th in the world in terms of population thus leading to an increased demand for wheat production so as to ensure food security in the country (Islam et al., 2021).So, there exists a dire need to accelerate wheat productivity for shrinking production-consumption gap.
Owing to the climatic conditions of Pakistan, many biotic and abiotic stresses contributed to the lower yield of cereal crops by affecting their enzymatic, physiological and, biochemical activities; one among the stresses is the unavailability and unawareness about the use of macro and micronutrients (Alotaibi et al., 2023).Sustainable wheat production can be achieved by application of micro and macro nutrients (Alotaibi et al., 2023).Inadequate provision of these nutrients is the prime cause beyond the suboptimal yield of wheat in Pakistan (Nadeem et al., 2023).
Nitrogen, in particular, plays an energetic role in metabolic activities of wheat such as respiration and photosynthesis.It is effective for the morphogenesis of many molecules including Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), hormones, pigments, Adenosine triphosphate (ATP), etc. in plants.Deficiency of Nitrogen, therefore, results in premature aging and poor growth in plants.Balanced use of nitrogen increases the amount of protein in the grain, spikes and tillers thereby producing an improved quality grain (Rafiq et al., 2023).
Similarly, Zinc is known as a vital nutrient for the survival of all living organisms and essential micronutrients for plants.The insufficiency of micronutrients has created dilemma of hidden hunger and malnutrition, by affecting 3 million of world's population (Saquee et al., 2023).It acts as a key element in numerous metabolic processes of plants such as enzymes regulation, chlorophyll production and, protein synthesis; its deficiency leads to poor development and growth of plants.Since Pakistan's soil is calcareous in nature, zinc deficiency is observed in its soil (Kamran et al., 2023).Hence, a wheat crop grown under Zn deficient soil will exhibit the symptoms of Zn deficiency in plants and their products.Therefore, in the light of the aforementioned studies, the present study assessed the foliar application of nutrients namely nitrogen and zinc for improved yield and growth of wheat crop in the area of Sindh, Pakistan.The main focus encompasses determining the impact of both, isolated and mixed foliar application of N and Zn during various stages of TD-1 variety of wheat.The study will create awareness among research and farming communities for the judicious use of foliar application of nitrogen and zinc at different growth stages of wheat crop to get maximum yield benefits.

MATERIALS AND METHODS Site Selection and Plant Material:
The field experiment was carried out at the student experimental farm, located at latitude 68.33° and longitude 25.25°, in the Department of Agronomy, Sindh Agriculture University, Tandojam, Sindh, Pakistan.The wheat variety TD-1 was compared to various foliar spray levels of N and Zn at both the tillering and booting stage.The entire study was set up using Randomized Complete Block Design (RCBD) and was duplicated three times.The size of the net plot was handled as 12 m 2 .The Agriculture Research Institute's Agronomy Section in Tandojam, Sindh, Pakistan, provided the seeds of wheat variety TD-1.Using a single coulter hand drill, the seeds were drilled in the experimental field.Following the instructions of Sindh's Agriculture Research Wing, 125 kg of seed was utilized as seed rate per hectare.On the other hand, rows and plants were separated by 30 and 75 cm spacings, respectively.November 2022 was the month of seed sowing, while March 2023 was the month of harvesting.

Land Preparation and Agronomic Management:
Two dry ploughings were applied to the site to break up the hard pan of soil and get rid of weeds.However, dry ploughing was followed by soft ploughing, which included clod crushing and leveling the field, before seedbed preparation.The aim was to provide a welldistributed seedbed and consistent application of water, fertilizer, and seed throughout field.During the whole growth season, the crop was kept free of weeds.Thirty days after seeding, as well as after the second and fourth irrigations, weeding and intercultural practices were performed.At the onset of crown root development, the first irrigation was given.From the sprouting of seedlings to crop maturity, a total of four irrigations were applied.Every morning, the crop was inspected for disease and insect pests, and appropriate action was taken if any issues were reported.When the crop reached its maturity, the harvesting process was carried out manually with the use of a sickle.Threshing of seeds of all plots was carried out by thresher except for seed index for which the seeds were obtained manually.

Foliar applications of N and Zn and Nutrition Management:
The wheat crop was subjected to seven foliar applications of N and Zn during tillering and booting stages.The treatments included T1 = Control, T2 = 2.0% N (tillering), T3 = 2.0% N (booting), T4 = 0.1% Zn (tillering), T5 = 0.1% Zn (booting), T6 = 2.0% N + 0.1% Zn (tillering), and T7 = 2.0% N + 0.1% Zn (booting).There was no treatment applied to the control plots.Nitrogen, Phosphorus and Potassium were applied in the form of Urea, Diammonium Phosphate (DAP), and Muriate of Potash (MOP) at the rate of 168-84-60 kg ha -1 , respectively.At the time of sowing, all DAP, MOP, and one-third of the urea were applied.The remaining urea was divided equally into two halves for the first and second irrigations.Trait Measurement: Five plants were chosen at random from each treatment in each replication, and were tagged.The data collection focused on plant height (cm), tillers (m 2 ), spike length (cm), grains spike -1 , grain weight (g plant -1 ) and seed index (1000seed weight) from those randomly selected plants; the average of five plants was obtained for each treatment.After attaining the plants' average, each treatment's average from all three replications was acquired and thereby utilized for statistical purpose.Manual threshing of seeds and weighing was carried out to get seed index.After determining the grain yield (kg plot -1 ) for each treatment, the following formula was used to convert the grain yield (kg ha -1 from kg plot -1 ):

Data analysis:
The STATISTIX-8.1 (www.statistix.com)program was used to analyze the replication-wise data that had been gathered.Tukey's Honestly Significant Difference (HSD) and Analysis of Variance (ANOVA) were programed to determine whether there were significant differences between treatments at the probability level (p ≤ 0.05).

RESULTS AND DISCUSSION Plant height (cm):
The data in relation to plant height (cm) of wheat variety TD-1 as affected by various combinations of foliar applied nitrogen and zinc are presented in Table 1.The results showed that all the treatments of nitrogen and zinc applied through foliar spray affected significantly (p ≤ 0.05) (Supplementary Table .1) plant height as compared to Control.The highest plant height 65.0 and 63.2 cm was recorded under T6 and T7, respectively.The diminishing trend in plant height of wheat was noted in T5 (60.3 cm), T4 (58.5 cm), T3 (55.7 cm) and T2 (55.5 cm).The statistical analysis shows no significant difference between T7 and T6, T5 and T4.The lowest plant height (51.3 cm) was recorded under control conditions.Our results confirm the findings of Farooqi et al., (2019) where they stated that 8% nitrogen supplied to foliage parts of wheat crop as liquid solution can significantly maximize the height of plants.A very recent study published by Kamran et al., (2023)  The results in Table 2 showed that maximum tillers 298.3 m -2 were recorded under T6, followed by T7, T5 and T4 with 288.3, 285.7 and 281.7 tillers m -2 .The T4 and T5 were statistically similar in terms of tillers m -2 .The minimum tillers 256.7 m -2 were observed in the plots where no foliar application was applied.Tillers (m -2 ) have a direct significant effect on wheat grain yield.The number of tillers (m -2 ) were significantly increased when all N, K and Zn were applied as foliar spray (Gull et al., 2011).Awwad et al., (2018) tested the efficiency of wheat crop against different planting methods and varying N levels applied as soil and foliar spray.
The maximum number of tillers (456 and 467 m -2 ) were produced when wheat field was supplemented with 60 kg N as soil + foliar application of urea in flat and terrace planting methods, respectively

Spike Length (cm):
The results showed in Table 3 reveals that the maximum spike length (9.2 cm) was perceived under T6 = 2.0% nitrogen + 0.1% zinc (tillering), followed by T7 = 2.0% nitrogen + 0.1% zinc (booting) and T3 = 2.0% nitrogen (booting) with 8.7 and 8.2 cm spike length, respectively.The diminishing trend in wheat spike length was noted when fertilized with 0.1% zinc at tillering stage, 0.1% zinc at booting stage and 2.0% nitrogen at tillering stage resulting in 7.8, 7.6 and 7.4 cm spike length.However, the plots where no foliar fertilization was applied remained lowest in spike length (7.0 cm).A recent study showed that 180 kg N, 18 kg Zn ha -1 combined with the application of 10 Kg humic acid gave a positive response in increasing the length of spikes of wheat crop (Iqbal et al., 2022).Farooqi et al., (2019) observed the highest 17.15 cm spike length when they treated their wheat crop with 8% N and 2% B foliar application.Zn along with other micronutrients such as Fe, Cu and B proved to be responsible for accumulating highest spike length in wheat crop (Ijaz et al., 2023).4 exhibited that the maximum grain spike -1 56.5 and 54.2 were recorded under T6 and T7, respectively and have no significant difference.The T5 and T4 produced 51.1 and 48.4 grain spike -1 , respectively and were statistically alike.The minimum grain spike -1 40.9 and 38.0 were recorded in T2 and T1, respectively and exhibited no significant difference between each other.Our results are in agreement with Bhutto et al., (2016); they investigated the performance of wheat against various foliar concentrations of zinc and concluded that 2.0% Zn was responsible in the increment of number of grain spike -1 .Similarly, Farooqi et al., (2019) also concluded that foliar spray consisting of 8% N significantly maximizes the quantity of grains per spike in the plants of wheat crop.Grain weight (g plant -1 ): The results shown in Table 5 displayed that the maximum grain weight 24.7 g plant -1 was recorded under T6 = 2.0 % nitrogen + 0.1 % zinc at tillering stage, followed by T7 = 2.0 % nitrogen + 0.1 % zinc at booting stage and T5 = 0.1 % zinc at booting stage with 22.0 and 20.1 g grain weight plant -1 .The diminishing trend in wheat grain weight g plant -1 was noted when fertilized with 0.1% zinc at tillering stage (T4), 2.0 % nitrogen at booting stage (T3) and 2.0 % nitrogen at tillering stage (T2) resulting in 17.5, 14.6 and 12.0 g grain weight plant -1 .However, minimum grain weight 10.1 g plant -1 was recorded under control conditions.Our results are in line with a recent study conducted by Lyu et al., (2022); documented that foliar application of urea significantly improved the weight of grains (mg) in comparison to foliar applied NO - 3 and NH + 4. The data shown in Table 7 exhibited that the maximum grain yield 5907.0 and 5758.0 kg ha -1 was recorded under T6 and T7 and exhibited no significant difference.While producing 5374.0 and 5167.7 grain yields (kg ha -1 ), T5 and T4 respectively, were also comparable to one another.The diminishing trend was observed in T3 and T2 where both these treatments produce 4753.0 and 4493.0 grain yield (kg ha -1 ), respectively.The minimum grain yield 4111.7 kg ha -1 was measured in T1.A two years experiment was conducted by Lyu et al., (2022) where they stated that grain yield of Xinong-20 and Xiaoyan-22 was enhanced when urea fertilizer applied as foliar spray along with other nitrogen forms.The highest grain yield in various wheat cultivars was achieved when Zn and N were applied combine with foliar and soil application methods (Coronado et al., 2017).Our results are also in agreement with Akram et al., (2017); concluded that grain yield of three wheat genotypes namely NIA-Amber, BWQ-4 and SD-998 was enriched when nitrogen and zinc were applied as 180 kg N and 10 kg Zn per hectare.Supplying nitrogen as 4% urea at tillering + heading stage of wheat can significantly improve the grain quantity of wheat crop (Shah et al., 2003).

CONCLUSION
It is concluded from the result that all the treatments of foliar applied nitrogen and zinc caused significant (p< 0.5) positive effect on growth and yield traits of wheat variety TD-1 as compared to control.Application of 2.0 % nitrogen + 0.1 % zinc was found most effective in producing morphological traits of wheat and maximizing yield and its components under agro-ecological conditions of Tandojam.It is recommended that farmers and growers can use 2.0 % nitrogen + 0.1 % zinc at tillering stage of wheat to get maximum grain yield (kg ha -1 ).

Table 1 . Plant height (cm) of wheat variety TD-1 as affected by foliar applied nitrogen and zinc at various growth stages
concludes that foliar applied ZnSO4 has the ability to produce taller wheat plants in comparison with control and zinc amino acid chelates (ZnAACH) .

Table 3 . Spike length (cm) of wheat variety TD-1 as affected by foliar applied nitrogen and zinc at various growth stages
The data shown in Table

Table 5 . Grain weight (g plant -1 ) of wheat variety TD-1 as affected by foliar applied nitrogen and zinc at various growth stages
Iqbal et al., (2022)so statistically alike.The diminishing trend in wheat seed index was observed in rest of the treatments.However, the minimum seed index 38.0gwasobserved in control treatment where no liquid N or Zn was applied.Iqbal et al., (2022)conducted an experiment to evaluate the morphological traits, yield and yield components of wheat against numerous applications of nitrogen, zinc and humic acid.They concluded that a combined application of 160 kg N, 18 kg Zn and 15 kg humic acid proved to be responsible for increased 1000-weight grain (g).This shows that N and Zn have the ability to increase grain yield by enhancing 1000-grain weight (g).The highest the concentration of Fe and Zn in foliar application the highest is 1000 grain weight(Akhter et al., 2022).