Efficacy of Soil Applied Phosphorus and Foliar Zinc Application on Different Growth Stages to Improve Productivity of Maize (Zea mays)

Fertilizers play an important role in crop production and also enhanced quality of crop (Amjadian et al., 2021). Balanced fertilizers are very important because it’s improved and enhances plant development and also increases yield (Hitha et al., 2021). Among the essential nutrients, phosphorus (P) is the second essential nutrient. Phosphorus (P) is important nutrient in the cropping system of agriculture (Roberts and Johnston, 2015; Guignard et al., 2017; Khan et al., 2018). It plays a role in crop development and in its metabolism (Yadav et al., 2017). Phosphorus is the part of nucleic acids, structural proteins and of enzymes (Yao et al., 2018). After nitrogen, phosphorus increases yield of crop (Adeyemi et al., 2020). Most of the cereal and vegetable crops require phosphorus in large quantity (Ketterings et al., 2020). It has two different forms in soil i.e. H2PO4-1 and HPO4-2 and plant takes it in these two forms. The absorption of HPO4-2is very rapid and faster as compare to H2PO4-1 (Alamnie and Misganew, 2021). Application of phosphorus give strength to straw of cereal crop and as a result crop lodging decreases. It also increases resistance to many diseases. It plays a crucial role in cell division, nucleus formation, helps in DNA and RNA formation (Kolodiazhnyiet al., 2021). Deficiency of phosphorus limits development and growth of plant (Kewei et al., 2014). Phosphorus decreases yield in maize crop when applied in low amount (Cengiz et al., 2020).

Micro-nutrients though are as important as macro-nutrients (Jake et al., 2022). However, as compared to macronutrients, micronutrients are required in very small amount. Generally, in most cases, both the plants and soils have very small amounts of micro-nutrients (Chakraborty et al., 2021). Micro-nutrients play a key role in plant growth and its development, improve crop phenology and also involve in various physiological processes (Hassan et al., 2019). Similarly, in case of micro-nutrients, Zinc (Zn) is an important micro-nutrient and plays a key role in plants (Natasha et al., 2022). Zn is necessary for biosynthesis of chlorophyll (Ali et al., 2021). In general, Zn has major role in activating enzyme, proteins synthesis, revival and oxidation reactions and carbohydrates metabolism (Ali et al., 2021). The deficiency of Zn may lead to photosynthesis decline and destruction of RNA, decreased protein synthesis, carbohydrates solution and thus affecting performance and quality of crop (Kadyampakeni and Chinyukwi, 2021). Foliar application of both Zn and Fe also enhances the phenological development and yield component of wheat crop (Ali et al., 2021). Application of Zn enhances height of maize crop when applied at split doses. Foliar Zn also significantly enhances size of maize leaf (Raheela et al., 2021).

The experiment entitled “efficacy of soil applied phosphorus and foliar zinc application on different growth stages to improve productivity of maize (Zea mays) was performed at Fodder and Forage crops section Harichand, Charsadda, Khyber Pakthunkhwa; Pakistan. The field experiment was conducted on 7 July 2021. The experiment comprised of the following factors along with their respective levels. Two levels of P (90 and 120 kg ha-1) were applied at the time of sowing and three levels of Zn (0 i.e., water spray only, 2.5 and 5 kg ha-1) were applied at three growth stages i.e., full at vegetative stage (V6), full at reproductive stage (R2) and½ at V6 and ½ at R2 stage along with an overall control were used in the experiment. The experiment was conducted in randomized complete block design with three replications. Treatment combinations of all the three factors along with a control were randomly allotted to the experimental plots in each block. Plot size was 4.9 × 4.0 m. Jalal variety was used for sowing. Planting was made on flat beds in rows spaced 0.70m. For application of Zn, 10% solution of ZnSO4.H2O was prepared. Keeping in view the treatments and volume to wet the subplot area completely, the solution was further diluted with water. Control plots were sprayed with equivalent quantity of water. First irrigation was given on 19 July 2021after sowing and subsequent irrigation was adjusted according to the need of crop. For all the treatments, other agronomic practices were kept uniform.

The experimental field is placed at 34.020 N, 71.470 E and 331 m above the level of sea. The mean annual rainfall of the location is 360 mm. The mean maximum summer temperature is 40 oC and the mean minimum is 25 oC while in winter minimum mean temperature is 4 oC and mean maximum temperature is 18.34 oC.

The soil characteristics as evaluated in laboratory and classified the soil as texture silty clay loam having 51.3% silt, 40% clay and 8.7% sand, 14.4% CaCO3, 8.08 pH and having low organic matter of 0.58% g kg-1. Similarly, the mineral contents of soil were i.e. 0.21 ppm zinc, 66.38 ppm iron, 2.86 ppm nickel, 1.07 ppm lead, .085 ppm chromium and 0.937 ppm was copper.

The data noticed on different parameters was analyzed statistically according to the procedure relevant to randomized complete block design as described by little and Hills (1978). Least significant difference (LSD) test were used for mean separation when the F test was significant.

Data of ear length showed in Table 1. Maximum ear length (17.8 cm) was noticed when 120 kg P ha-1was applied while minimum (16.8 cm) was noticed when 90 kg P ha-1was applied. The reason for increased of ear length of maize might be that phosphorus could translocate assimilation to ears has accrued and have been resulted in to increased ear length (Juan et al., 2021). Similarly, in case of Zn, maximum ear length (18.4 cm) was observed when 5 kg Zn ha-1was applied while minimum (16.1 cm) was noticed with water spray only. Ear length and weight increased with higher rate of Zn (Hisham et al., 2021). In case of Zn application timing, maximum ear length (18.2 cm) was recorded when Zn was applied all at AT3 stage while minimum (16.5 cm) was noticed when applied all at AT1 stage.

Data concerning ear weight are accessible in Table 2. Maximum ear weight (115.8 g) was noticed when 120 kg P ha-1was applied while minimum (109.4 g) was observed when 90 kg P ha-1was applied. Ear weight of maize crop increased with higher rate of phosphorus because phosphorus increases the amount of endosperm in grain (Perkins et al., 2021). Similar in case of Zn, maximum ear weight (129.6 g) was noticed when 5 kg Zn ha-1was applied while minimum (113.4 g) was noticed with water spray only. Increase of ear weight is due to the heavier grain weight, because zinc provided adequate amount of carbohydrates to source. Therefore, ear weight increases with the application of Zn (Liu et al., 2020). In case of Zn application timing, maximum ear weight (127.4g) was shown when all Zn was applied at AT3 stage while minimum (111.4 g) was noticed with all at AT2 stage. In such away in case of P x AT interaction, the maximum ear weight (124.1 g) was noticed in plots when 120 kg P ha-1 and Zn applied half at V6 and half at R2 stage while minimum (97.9 g) was noticed in plot that received 90 kg P ha-1 and all Zn at AT2 stage.

Table 1: Ear length (cm) of maize as affected by phosphorus, foliar Zn and its application timing.

Table 2: Ear weight (g) of maize as affected by phosphorus, foliar Zn and its application timing.

Data concerning grains ear-1 are obtainable in Table 3. In case of P, maximum grains ear-1 (390) was shown when 120 kg P ha-1was applied while minimum (369) grains ear-1 was noticed when 90 kg P ha-1was applied. Phosphorus is responsible for the growth of root which directly affects the overall plant performance (Bing et al., 2022). It has also reported that grains per ear also increase with phosphorus fertilization (El-Sobky et al., 2021). Similarly, in case of Zn, maximum grains ear-1 (407) was noticed when 5 kg Zn ha-1 was applied while minimum (353) was shown with water spray only. This is because that Zn is essential for pollen grain development and pollen viability; as a result, number of grains increases in ear (Sonal et al., 2022). In case of Zn application timing, maximum (391) was noticed when Zn was applied half at V6 and half at R2 stage while minimum (372) was noticed when all applied at AT2 stage.

Table 3: Grains ear-1 of maize as affected by phosphorus, foliar Zn and its application timing.

Data regarding thousand grains weight are obtainable in Table 4. Statistical analysis of the data show that maximum thousand grains weight (257 g) was seen at 120 kg Pha-1and minimum (233.7 g) thousand grains weight were seen at 90 kg p ha-1 application. Heaviest grain weight with higher P level probably may be due to higher P translocation in to the fruiting area which results in highest grain weight. Increasing in P levels increased grain weight (Hamza et al., 2022). Similarly, in case of Zn, highest (258.3 g) thousands grain weight was noticed when 5 kg Zn ha-1was applied while minimum (220.5 g) was noticed with water spray only. When the supply of carbohydrates to grain is high then the filling of grain will be high and as a result weight of kernels will be more (Wenxin et al., 2017). In case of Zn using timing, maximum thousands grain weight (255.5 g) was shown when Zn was applied half at V6 and half at R2 stage while minimum (228.6 g) was noticed when applied all at V6 stage.

Table 4: Thousand grains weight (g) of maize as affected by phosphorus, foliar Zn and its application timing.

It is concluded from the experiment that application of 120 kg P ha-1 significantly improved ear length, ear weight, grains per ear and thousand grain weight. Similarly, foliar application of 5 kg Zn ha-1 improved ear length, ear weight, grains per ear and thousand grain weight of cob. In case of application timing of zinc, when applied ½ at vegetative and ½ reproductive stage will improve productivity of maize crop. Therefore,120 kg P ha-1, 5 kg Zn ha-1 along with its application timing ½ at vegetative and ½ reproductive stage is recommended for the agro climatic conditions of Peshawar.

This study conducted to find out the impact of phosphorus, Zinc and its application stages to improve maize yield.

Sajid Ali: Carried out research and drafted the manuscript.

Shahen Shah: Provided technical guidelines

Muhammad Amin: Helped in data analysis

Asad Ali Khan: Helped in editing and draft improvement

Dawood Ahmad and Ikram Ullah: Helped results and discussion interpretation

Faiq Ahmad and Sajjad Khan: Helped in data collection

Sikandar Azam: Helped in format setting

The authors have declared no conflict of interest.