Foliar application of nitrogen at different growth ... - Soil & Environment

Soil Environ. 32(2): 135-140, 2013 www.se.org.pk

Online ISSN: 2075-1141 Print ISSN: 2074-9546

Foliar application of nitrogen at different growth stages influences the phenology, growth and yield of maize (Zea mays L.) Amanullah*1, Amir Zaman Khan1, Amanullah Jan1, Zahir Shah2, Bashir Ahmad1, Shah Khan Khalil1, Asad Ali1, Hidayatullah1, Fawad Ahmad1 and Asif Nawaz3 1 Department of Agronomy, The University of Agriculture Peshawar 2 Department of Soil and Environmental Sciences, The University of Agriculture, Peshawar 3 Department of Agriculture and Extension, The University of Agriculture, Peshawar

Abstract Foliar fertilization has been widely used and accepted as an essential part of crop production. The objective of this study was to investigate the response of maize (Zea mays L., cv. Azam) to foliar application of nitrogen (2%) from different sources viz. urea, ammonium sulphate (AS) and calcium ammonium nitrate (CAN)] and its application time [15, 30, 45, and 60 days after emergence (DAE)]. The experiment was laid out in randomized complete block design (RCBD) with split plot arrangement using four replications at the research farm of the University of Agriculture Peshawar during summer 2010. Phenological development was delayed, while plant height, 1000-grains weight, grains ear-1, biomass and grain yield as well as harvest index was increased with foliar application of N than water spray (control). Plant height, leaf area, biomass and grain yield was increased when foliar-N was applied late (45 and 60 DAE) than early (15 and 30 DAE) application. It was concluded from the results that late foliar-N application (urea, CAN or AS) about one week before tasseling up to silking could increase maize productivity in the study area. Keywords: Method, nitrogen, source, phenology, growth, yield

Introduction Foliar fertilization has been documented as early as 1844 to correct iron deficiency. Foliar fertilization is widely used to correct nutritional imbalances in plants. Foliar fertilization is an agricultural practice extensively used to increase yield and quality of various crops (Romheld and El-Fouly, 1999). Supplying a plant’s major nutrient needs (N, P, and K) is most effective and economical via soil application. However, for short and/or critical growth periods of a crop, foliar application has proved to be an excellent method as supplementing N-P-K needs (Curley et al., 1994). The efficacy of foliar fertilization is higher than that of soil fertilizer application under drought conditions (Ahmad et al., 2013) and in saline soils. In such conditions, the required nutrients are supplied directly to the location of demand in the leaves and are quickly absorbed. Another reason for high efficacy of foliar application is the independence of root activity and soil water availability (Romheld and El-Fouly, 1999). Nitrogen is a primary constituent of protein and is extremely susceptible to loss. Split application of N during growing season is considered an important agronomic practice to enhance crop utilization (Boman et al., 1995). In wheat, both pre-plant and in-season application of N showed increase in grain yield and protein content of grains (Cassman et al., 1992). Application of N late in the growth season allows farmers to adjust N rate in accordance with crop growth (Woolfolk et al., 2002). This also reduces potential N

losses from denitrification and leeching. Increases in N content of grains were often larger when applications of Nfertilizers to the soil were reduced, and when the foliar-N was applied either at anthesis or during the following two weeks (Gooding and Davies, 1992). Urea has been used in foliar sprays to correct chlorotic leaves caused by N-deficiency (Shimshi, 1967). The foliar application of nitrogen causes a tremendous increase in yield of crops. Significant increase in maize grain yield was achieved when a supplemental dose of 7 kg N ha−1 as urea spray was applied (Singh et al., 2005). Foliar N application, late-season, showed significant effect on yield, total grain N and straw yield of maize (Woolfolk et al., 2002). Amanullah et al. (2010) reported significant effects of foliar application of nitrogen on phenology, growth and yield of maize. They concluded that 6% urea application as foliar spray increased yield and yield components of maize. Grain yield, stover yield, grains ear-1, 1000-grain weight, and grain weight ear-1 increased significantly up to 6% N (Sanjeev et al., 1997). On the other hand, compared with soil N application, neither foliar spray nor injection through the ear affected grain yield or stover dry matter of maize (Ma et al., 2004). Foliar application of urea increased grain protein content in barley more effectively than broadcast NH4NO3 (Balman and Smith, 1991). Nitrogen management is considered the most important factor affecting maize growth (Amanullah et al., 2008),

*Email: [email protected] © 2013, Soil Science Society of Pakistan (http://www.sss-pakistan.org)

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Foliar application of nitrogen to maize

phenology and grain yield (Amanullah et al., 2009). Studies regarding efficiency of N-source used in the form of foliar spray and its application timing are not carried out on maize in this agro-ecological zone of Pakistan. The present study was, therefore, initiated to determine the most efficient foliar Nsource and its application time for increasing maize productivity.

Materials and Methods Site description The experiment was conducted at New Developmental Farm (34° N and 71.3° E), the University of Agriculture Peshawar, Pakistan, during summer, 2010. The Farm is located at an altitude of 350 m above sea level at about 1600 km north of Indian Ocean. The climate of this agro-ecological zone is sub-tropical, sub-humid and continental with mean daily maximum (summer) temperature 40 to 44 °C and minimum (winter) 4 to 5 °C. Mean annual rainfall varies from 450 to 750 mm with more rains (about 60%) in summer months. Water from Warsak canal (Kabul River) is used for irrigation purpose. Soil analyses were carried out for organic matter (Nelson and Sommer, 1982), pH (McClean, 1982), P and K (Soltanpour, 1985). The soil texture is clay loam and calcareous in nature, low in organic matter (0.81%), alkaline in reaction (pH 8.1), having high exchangeable K (496 mg K2O kg-1), lower total N (0.04%) and AB-DTPA extractable P (1.1 mg P2O5 kg-1) (Amanullah et al., 2009).

Experimentation A 4 × 4 factorial experiment was laid out in randomized complete block (RCB) design with split-plot arrangement having four replications. Two percent solution of four nitrogen sources [S1 = water (control); S2 = urea; S3 = ammonium sulphate (AS); and S4 = calcium ammonium nitrate (CAN)] was applied to main plots and there were four application timings (15, 30, 45 and 60 days after emergence). Sources of foliar-N were kept in main plots, while application timings were kept in subplot. A sub-plot size of 4.9 m × 4 m, having 7 rows, 4 m long and 70 cm apart was used. A uniform basal dose of 60 kg ha-1 P2O5 as single super phosphate (18% P2O5) was applied and mixed with the soil during seedbed preparation. A basal dose of N at the rate of 80 kg N ha-1 as urea was also applied. The maize cultivar “Azam” was used as test crop. The crop was irrigated at two weeks interval. Carbofuran (3%) at 19.76 kg ha-1 was applied to control attack of stem borer in the early stages (two weeks after emergence). In all subplots, standard agronomic practices were followed throughout the growth period. Data regarding phenology, growth and yield were recorded. Days to tasseling and silking were counted from emergence till 50% of the plants in each subplot produced

tassels and silk, respectively. Number of days to maturity were counted from planting till the plants fully matured. Plant height (cm) was taken from base of the 5 randomly selected plants to the top in each subplot and then average was worked out. Leaf area plant-1 was calculated from 3 randomly selected plants in each subplot. Leaf area of three middle leaves was measured with the help of LI-3000 leaf area meter (LiCor Inc., Lincoln, NE) and averaged. From each treatment five ears were selected and their numbers of grains were counted after threshing each ear separately and then average was worked out. Thousand grains were taken at random from the grain lot of each subplot and weight by electronic balance. This was repeated thrice and then average weight per 1000 grains were calculated and recorded. Data on biomass yield was recorded after harvesting the three middle rows from each subplot. The harvested material was dried up in open air to constant weight, weighed and converted into biomass yield (kg ha-1). From the dried material (biomass) in each experimental plot; ears were removed, husked, shelled and weighed. Grain yield was recorded per unit area and then converted into in kg ha-1. Harvest index was calculated according to the following formula: Harvest index % =

Grain yield unit area-1 ×100 Biomass yield unit area-1

Statistical analysis Data were statistically analyzed according to Steel et al. (1997) and means were compared using LSD test (p < 0.05).

Results and Discussion Phenology Foliar N application time had significant effects on tasseling, silking and maturity of maize, while N source had only significant effects on days to silking and maturity (Table 1). Tasseling was delayed with late (45 and 60 DAE) application of foliar N (Table 2), while early (15 and 30 DAE) application of foliar N enhanced tasseling in maize by one day (56 days). Early silking (61 days) were observed in plots spayed with AS (Table 2), while late silking (63 days) was observed in the control plots (water spray). Silking was delayed (63 days) in plots which were spayed at 60 DAE. Foliar N sources (urea, CAN, and AS) significantly delayed maturity in maize than control (water spray only). Among the N sources, urea and CAN delayed maturity by one day as compared with AS (Table 2). Foliar-N application at 45 and 60 DAE delayed maturity (94 days) as compared to early application (15 or 30 DAE) which enhanced maturity in maize by two days. Interactions of N-source into application time had no significant effects on maize phenology (tasseling,

Amanullah, Khan, Jan, Shah, Ahmad, Khalil, Ali, Hidayatullah, Ahmad and Nawaz silking and maturity). Delayed silking and maturity was observed when N was sprayed in the form of urea and CAN as compared to AS. These results are in close conformity with the findings of Karim et al. (1983), who observed delayed tasseling and maturity with urea spray. Late application of foliar-N increased the vegetative growth period, resulting in delayed tasseling, silking and maturity. An early study showed that late application of foliar urea at V12 stage (ear shoots were formed just before tassel formation) increased the vegetative growth period of maize, resulting in the late initiation of tassels, silking and maturity (Amanullah et al., 2010); those were in line with our results.

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minimum (190 cm) with water spray (no N). Among the time of foliar spray, delayed application (60 DAE) produced taller plants (203 cm), followed by 30 and 45 DAE each with 198 cm, and the shortest plants (190 cm) were recorded when spray was applied at 15 DAE. Foliar N application time had significant effects, while N source and interaction had no significant effects on mean single leaf area of maize (Table 1). The highest leaf area (451 cm2) was noted when foliar N was applied late (60 DAE), and the lowest leaf area (409 and 408 cm2) was obtained with early sprays (Table 2). Although N sources had no significant effects on leaf area, yet water spray reduced the leaf area when compared with three sources of N.

Table 1: Summary of analysis of variance (ANOVA) for various parameters of maize (Zea mays L.) studied during the experiment Parameter Days to tasseling Days to silking Days to maturity Plant height Mean leaf area Biomass yield Grains ear-1 1000- grains weight Grain yield Harvest index

Unit Number Number Number cm cm2 kg ha-1 Number g kg ha-1 %

Foliar N-source (S) ns * * * ns * * * * *

Application time (T) * * * * * * ns ns * ns

Interaction (S x T) ns ns ns ns ns ns ns ns ns ns

*denotes significant at p ≤ 0.05, and ns refers to not significant.

Table 2: Growth and phenological parameters of maize (Zea mays L.) as affected by time and source of foliar application of nitrogen Treatment Foliar N-Source Control (water spray) Urea CAN AS LSD (p ≤ 0.05) Application Time (DAE) 15 30 45 60 LSD (p ≤ 0.05)

Days to tasseling

Days to silking

Days to maturity

Plant height (cm)

Leaf area (cm2)

57 56 57 56 ns

63 62 62 61 1.0

90 95 95 94 0.7

190 204 199 195 10.7

373 453 430 444 ns

56 56 57 57 0.5

62 61 62 63 0.6

92 92 94 94 0.7

190 198 198 203 9.7

409 408 432 451 38

*Where ns stands for non significant, and DAE for days after emergence

Growth parameters Foliar N-source and its application time had significant effects, while interaction had no significant effects on plant height of maize (Table 1). Tallest plants (204 cm) were produced by maize with application of urea, and it reduced to

Application of foliar N sources increased plant heights which may be due to extended growth period of maize. Among Nsources, urea and CAN produced taller plants than AS. The presence of sulfur in AS probably may have enhanced maize phenological development that may have resulted in shorter plants. Increase in plant height and leaf area was more when

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foliar-N was applied late (60 DAE). An earlier study regarding foliar urea application at various growth stages of maize (Amanullah et al., 2010) revealed that late application of urea increased plant height and mean single leaf area in maize. Foliar application of urea to chlorotic leaves (Ndeficient) of maize restored both normal chlorophyll content and normal stomatal behavior which might be the possible cause of increase in plant heights and leaf area expansion in maize (Shimshi, 1967). Foliar N sources and timing had significant effects, while interaction had no significant effects on biomass yield of maize (Table 1). All foliar N-sources (urea, CAN, and AS) had significantly higher biomass yield than control (water spray only). Among the N source, urea (9283 kg ha-1) and AS (9254 kg ha-1) produced higher biomass yield than CAN (8703 kg ha-1) and control (7973 kg ha-1). Among the time of foliar spray, delayed application of foliar spray (60 DAE) resulted in higher biomass yield (9145 kg ha-1), followed by 30 DAE (9060 kg ha-1), and the lowest biomass yield (8424 kg ha-1) was produced when the spray was applied at 30 DAE. The delay in maturity, increase in plant height and leaf area resulted in higher biomass yield in maize which indicated positive relationship of biomass yield with extended maturity period, increase in height and leaf area. Amanullah et al. (2010) suggested that late application of urea increased biomass yield in maize because of the extended growth period of maize. Woolfolk et al. (2002) reported that late season foliar N application increases stover yield and total straw N. However, Below et al. (1985) reported that stover yield is unaffected by the foliar treatment after anthesis stage to enhance or extend the accumulation of dry weight.

Yield parameters Foliar N sources had significant effects, while foliar

application time and interaction had no significant effects on number of grains ear-1 and 1000 grain weight of maize (Table 1). Among the N-sources, application of AS produced the highest number of grains ear-1 (407), followed by CAN (397), while the lowest number of grains ear-1 (350) was recorded in the control plots (Table 3). In maize, grain yield mainly depended upon the number of grains plant-1 (Otegui et al., 1995). Grains ear-1 was significantly increased with foliar-N application regardless of application timing. Previous studies (Sarandon and Gianibelli, 1990; Sanjeev et al., 1997; Amanullah et al., 2010) showed that foliar-N fertilization increased number of grains ear-1 in maize. However, increase in number of grains ear-1 was more when foliar-N was applied in the form of AS than CAN and urea. The presence of free sulfur (S) in AS probably may have positive impact on the formation of grains-1 ear in maize. Chien et al. (2011) declared that AS was the best N-fertilizer source. Among the sources, all the three N sources produced heavier grains (234-238 g/1000 grains), than water spray (224 g/1000 grains). Foliar N sources and its application time had significant effects, while interaction had no significant effects on grain yield of maize (Table 1). Grain weight of maize also increased considerably with source of foliar application. Application of three sources increased grains weight more than water spray. Foliar N (urea, AS, CAN) application increased grain fill duration (tasseling to maturity) and so more photosynthate was partitioned to grains that resulted in heavy grains of maize. During anthesis and grain filling stages, up to 90% of N required for the ear development came from remobilization of the stored N in stalks and leaves (Ta and Weiland, 1992). Moreover, the three N sources also increased mean single leaf area that probably might have increased the rate of photosynthesis that might have increased grains weight. According to Harder et al. (1982), foliar N fertilization increased photosynthetic rate of maize leaves

Table 3: Yield parameters of maize (Zea mays L.) as affected by time and source of foliar application of nitrogen Parameter Foliar N-Source Water (Control) Urea CAN AS LSD (p ≤ 0.05) Application Time (DAE) 15 30 45 60 LSD (p ≤ 0.05)

Biomass yield (kg ha-1)

Grains ear-1

7973 9283 8703 9254 811

350 386 397 407 43

224 238 234 236 10

2853 3453 3383 3559 421

35.8 37.3 39.0 38.4 1.3

8585 8424 9060 9145 519

381 390 393 377 ns

227 234 232 239 ns

3163 3141 3413 3531 294

36.9 37.4 37.7 38.5 ns

*Where ns stands for non significant, and DAE for days after emergence

1000- grains weight (g)

Grain yield (kg ha-1)

Harvest index (%)

Amanullah, Khan, Jan, Shah, Ahmad, Khalil, Ali, Hidayatullah, Ahmad and Nawaz hence resulted in accumulation of more photo-assimilates in the grains resulting in heavier grains. Amanullah et al. (2010) found that foliar-N fertilization increased leaf area and maintained functional leaf area for longer time which might be the possible reason for increasing photo-assimilate formation that increased grain weight. These results are also supported by earlier studies (Strong, 1982; Lawlor et al., 1989). All foliar N-sources (urea, CAN, and AS) produced higher grain yield than control (water spray only). However, there were no significant differences in the grain yield of maize when applied with three sources of N (33833559 kg ha-1). Delayed application of foliar N (60 DAE) gave higher grain yield (3531 kg ha-1), followed by 45 DAE (3413 kg ha-1), while the lowest grain yield (3141 kg ha-1) was recorded when the spray was applied at 30 DAE. However grain yield obtained with foliar spray at 15 and 30 DAE were statistically the same (Table 3). Grain yield was significantly increased with foliar-N source compared to control (water spray) and the best time for N spray was 60 DAE. It can be inferred from these results that extended growth period, increase in mean single leaf area, number of grains ear-1 and 1000-grains weight translated into higher grain yield. Gooding and Davies (1992) reported that foliar urea (N) applications increased grain yield in maize, particularly when applied before flag leaf emergence and when N availability was limiting. Our earlier study showed that late application of foliar urea at V12 stage (ear shoots were formed just before tassel formation) significantly increased grain yield in maize (Amanullah et al., 2010) due to improvement in the yield components. Singh et al. (2005) suggested that a supplemental foliar application of urea at 7 kg N ha-1 significantly increased maize grain yield. In wheat crop, significant increase in grain yield was found by Dampney and Salmon (1990) when foliar-N was sprayed during and after anthesis. Foliar N sources had significant effects, while application time and interaction had no significant effects on the harvest index of maize (Table 1). All foliar N-sources (urea, calcium ammonium nitrate, and ammonium sulphate) had significantly higher harvest index than control (water spray only). Among the N source, CAN with harvest index of 39.0% stood first, followed by AS (38.4%), and control (35.8%) stood in the bottom in terms of harvest index (Table 3). Although timing of foliar spray had no significant effects on harvest index, yet delayed application of foliar spray (60 DAE) resulted in higher harvest index (38.5%), and the lowest harvest index (36.9%) was recorded when the spray was applied at 15 DAE. The increase in yield components (grain weight and grains ear-1) and grain yield resulted in higher harvest index in maize and indicating positive relationship of harvest index with yield components and grain yield. Amanullah et al. (2010) reported

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that the increase in grain yield with urea application at the V12 stage might be due to the extended growth period, increase in grain weight and number of grains per ear that probably may have resulted in higher harvest index in maize.

Conclusion This study suggests that late (45-60 DAE) foliar application of N (2%) in the form of either urea, AS or CAN delayed phenological development, improved crop growth and yield of maize. So, it may be concluded that supplementation of maize crop with 2% foliar spray along with soil application can be a useful strategy to get improved yield of maize.

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