Original Research

Response of maize varieties to fertilizer levels in Chitwan valley condition of Nepal

Bandhu Raj Baral*, Tika Bahadur Karki, Jiban Shrestha

Nepal Agricultural Research Council,National Maize Research Program, Rampur, Chitwan, Nepal

J Innov Biol (2014) Volume 2, Issue 1: Pages: 217-221

Abstract: Maize genotypes with optimum plant nutrients are essential for enhancing productivity. To identify suitable rates of fertilizers (major nutrient NPK) to different maize genotypes, a field experiment was conducted at Rampur, Chitwan, Nepal during summer season of 2012. Two levels of Phosphorus and Potash (60:40 kg P2O5:K2O ha-1 and 90:60 kg P2O5: K2O ha-1) with four levels of Nitrogen (0, 120, 180, 240 kg N ha-1) were tested for hybrid maize variety Rampur Hybrid 2 and open pollinated variety Rampur Composite. Plant height, ear height, dry matter accumulation, ear length, no of kernels per row significantly increased with increased level of Phosphorus and Potash and Nitrogen. Grain and stover yield was increased with increased Nitrogen levels and was higher in Rampur Hybrid 2 than Rampur Composite. Highest grain yield (4.50 ton ha-1) was recorded in Rampur Hybrid 2 with 240 kg N ha-1with 90:60 kg P2O5:K2O ha-1. Rampur Composite did not respond on grain yield increase with increasing the PK level (90:60 kg P2O5: K2O ha-1) and only responded up to 180 kg N ha-1 along with 60:40 kg P2O5: K2O ha-1 level. The results on grain yield and monetary return of fertilizer application revealed that for harnessing maximum yield benefit from Rampur Hybrid 2, 240 kg N ha-1 can be applied with increased PK level (90:60 kg P2O5: K2O ha-1). For Rampur Composite, application of 60:40 kg P2O5:K2O ha-1 and 180 kg N ha-1 gave comparatively higher net returns and benefit: cost ratio.

Received: 26 October 2014
Accepted: 08 December 2015
Published: 22 January 2015


Corresponding Author:
Barbal B.R.,
Nepal Agricultural Research Council,National Maize Research Program, Rampur, Chitwan, Nepal
email: bandhu.baral@gmail.com

Keywords: Dry matter, fertilizers, grain yield, maize genotypes and Rampur Hybrid 2

IntroductionMaterial & MethodsResults & DiscussionFigures & TablesReferences
Inappropriate crop nutrition management and poor soil fertility are the most important factors responsible for the low crop productivity in Nepal. Soil fertility can be enhanced through the application of mineral fertilizers as well as with the addition of organic matter to the soil. The judicious management of fertilization must attempt to ensure both an enhanced and safeguarded environment. Manures and fertilizers both play important role in the maize cultivation. Maize requires adequate amount of nutrient particularly nitrogen, phosphorus and potash for good growth and high yield. Nitrogen is vital plant nutrient and yield determining factor required for maize production (Adediran and Banjoko 1995; Shanti et al, 1997). Nitrogen is a component of protein and amino acid and when limited growth is reduced. It also mediates Phosphorus, Potassium and other elements in plant (Brady 1984). After Nitrogen, Phosphorus is another most important nutrient for maize growth. Phosphorus plays important role in various enzymatic reactions. It is essential for cell division because it is the constituent of nucleoproteins. Similarly, Potassium is third most important nutrient for maize. Potassium plays important role in grain filling because it helps to translocation of carbohydrates. It helps to strengthen fibrous tissue thus prevents from lodging and tolerant to disease and insect pest to some extent. The requirement of these three nutrient elements in maize largely depends on genotypic make of plants, nutrient supplying capacity of the soil, soil moisture, environmental condition and yield target. Hybrids and composite varieties exhibit their full yield potential only when supplied with adequate quantities of nutrients at proper time. For optimum yields, hybrid maize requires high doses of fertilizer (Gardner et al, 1990; Killorn and Zourarakis, 1992) possibly because their development is usually under high N fertilizer applications (Purcino et al, 1998; Bertin and Gallais, 2000). Singh et al (2000) reported that grain and stover yield increased with increasing N levels from 0 to 200 kg ha-1.
Our existing fertilizer recommendation dose of 120:60:40 kg N:P2O5:K2O ha-1 is blanket for all the varieties of maize. Therefore, a location specific and variety specific fertilizer response study was lacking. The present investigation was undertaken to study the response of major nutrient NPK levels on maize varieties at Chitwan valley condition of Nepal.

This experiment was conducted at National Maize Research Program (NMRP) farmland during the summer season of the year 2012. The site was located in central inner terai region of Nepal at 27o 37’ N latitude and 84o 25’ E longitude with an elevation of 256 meters above mean sea level. The crop was planted in May, 2012 and harvested in September, 2012. Two maize varieties one hybrid named as Rampur Hybrid 2 and other open pollinated variety Rampur Composite were tested for fertilizer response with two levels of PK (60:40 kg P2O5: K2O ha-1 and 90:60 kg P2O5: K2O ha-1) and four levels of Nitrogen (0, 120, 180 and 240 kg N ha-1).

The experiment was laid out in randomized split-split plot design as variety main plot, PK level sub plot treatment and N levels sub-sub plot treatment and replicated three times. Row to row spacing was maintained at 60 cm for each plot. Plant to plant spacing was maintained at 25 cm. The plot size was 10.8 m2. Maize was sown on Dystric Ustochrepts sandy loam soil type, medium acidic (pH 5.8), low organic matter 2.6%, low available N 0.133%, high available Phosphorus 96 kg ha-1 and medium available potassium 123 kg ha-1. Fertilizers were applied in the form of Urea, Single Super phosphate (SSP), and Mureate of potash (MoP). Entire dose of SSP and MoP was applied at the time of sowing while 1/3 of urea was applied at sowing and 1/3rd top dressed at knee high stage and 1/3rd was second time top dressed at tasseling stage. Observations were taken on periodic dry matter accumulation at 45 days after sowing (DAS) and 90 DAS, plant height, ear height, ear length, no. of Kernel rows per ear, no. of kernels per kernel row, stover and grain yield. Soil samples were collected before crop planting (composite sample) and after harvesting and analyzed for nutrient content. Analysis of variance (ANOVA) for all parameters was analyzed using Genstat 13 program.

Growth characteristics
Plant height was significantly influenced by PK and N levels. Increased level of PK and N had increased plant and ear height (Table 1). The plant height was also varied with variety but the ear height did not differ. Rampur Composite was taller than Rampur Hybrid 2. This indicates that plant height was controlled by genotype as well as nutrient levels. The results on dry matter accumulation shows that no difference seen between varieties both at 45 and 90 DAS. There was significant interaction of PK and N on dry matter accumulation at both 45 DAS and 90 DAS but interaction of variety and N were only seen on dry matter accumulation at 90 DAS. At 45 DAS, the dry matter accumulation was increased with increasing N level at 0 to 120 kg N ha-1 along with increasing PK level. At 90 DAS, the dry matter accumulation was increased with increasing N levels at low PK level (60:40 PK) on Rampur Composite. This indicates that at early growth stage (45 DAS) no varietal differences seen on dry matter accumulation but after 45 DAS, Rampur Composite grew faster than Rampur Hybrid 2 and response of increased PK level was not seen in Rampur Composite. Higher N applications increase the cell division, cell elongation, nucleus formation as well as green foliage. It also encourages the shoot growth. Therefore, higher doses of nitrogen increased the chlorophyll content which increased the rate of photosynthesis and extension of stem resulting increased plant height and dry matter (Thakur et al. 1997). Days to 50% plant tasseling and silking was highly influenced by the interactive effect of variety × PK level × N level. The tasselling and silking days were longer in Rampur Hybrid 2 at low PK level and N level. The tasseling and silking trend indicates that increasing PK level upto 180 kg N ha-1 hasten early tasseling and silking in Rampur Hybrid 2.These results corroborated with Bakth et al. (2006) who reported that increased N at 200 kg N ha-1 induced earliness of tasseling and silking.

Yield parameters
The no. of ears per plot did not significantly differ among varieties and PK levels (Table 2). But it was influenced by levels of N. Increasing N levels from 0 to 180 kg ha-1 had increased no. of ears per plot. However, at 240 kg N ha-1 did not increase no. of ears per plot which was at par with the no. of ears per plot at 180 kg N ha-1. The no. of unfilled ears per plot was resulted from the significant interaction between var × PK and var × N. Rampur Hybrid 2 had higher number of unfilled ears per plot at lower PK and N level while in Rampur composite at 90:60 kg P2O5:K2O ha-1 and more than 120 kg N ha-1 N did not affect on no. of unfilled ears per plot. The higher no. of unfilled ear per plot under low N application might be due to poor development of sinks and reduced translocation of photosynthates. Under limited nitrogen supply there may be poor protein synthesis leading to reduction in the number of seeds. This result revealed that at least 120 kg N ha-1 is optimum to overcome the no. of unfilled ears per plot. Increasing PK level had increased significantly ear length. There was significant interaction effect of var × N on ear length. Increased N levels from 0 to 180 kg N ha-1 had significantly increased ear length in Rampur Hybrid 2. In contrast, increased N level did not increase ear length in Rampur Composite except at 120 kg N ha-1 in compared to 0 kg N ha-1. The no. of kernel rows per ear was only varied between varieties and was not differed with PK and N levels. High PK level had significantly increased numbers of kernels per row. Similarly, the no. of ears per row had significant interaction effect of var × N levels. Higher no. of kernels per row was found with high N level in Rampur Hybrid 2 than Rampur Composite. In Rampur Composite, increased N levels did not show significant difference on no. of kernel per row on both low and high PK levels. There was a significant interaction between var × PK × N on 1000 grains wt. The 1000 grains wt. was increased at 120 kg N ha-1 in Rampur Composite in both PK levels. In agreement with results of the present study, increased in 1000 grains wt. has been reported with increase in nitrogen levels (Akbar et al. 2002). However, at 0 kg N ha-1, higher 1000 grains wt. was recorded on high PK level than low PK level on both varieties. In Rampur Hybrid 2, no difference observed in 1000 grains wt. with increased PK levels.

Grain and stover yield, harvest index and economic return
Grain wt. per plant, grain yield and stover yield were significantly affected by varieties and N levels (Table 3). Grain wt. per plant and grain yield per ha showed similar trends as increasing N levels had increased grain yield. Higher grain yield was recorded in Rampur Hybrid 2 than Rampur Composite. Highest grain yield (4.50 ton ha-1) was recorded in Rampur Hybrid 2 with 240 kg N ha-1 with high PK level (90:60 kg P2O5:K2O ha-1). Rampur Composite did not respond on grain yield increment with high PK level and only responded up to 180 kg N ha-1 along with 60:40 kg P2O5:K2O ha-1. The results on grain yield revealed that for harnessing maximum yield benefit from Rampur Hybrid 2, 240 kg N ha-1 can be applied with 90:60 kg P2O5:K2O ha-1. Our results were in line with Singh et al. (2000), grain and stover yield increased with the increase in N level from 0 to 200 kg ha-1. For Rampur Composite, only up to 180 kg N ha-1 showed grain yield benefit at low PK level. Higher stover yield was also recorded in Rampur Hybrid 2 than Rampur Composite. Stover yield at120 kg N ha-1 was significantly higher than 0 kg N ha-1 and was at par with 180 and 240 kg N ha-1. The residual soil organic matter, pH and available N was not much influenced by treatment effect on nutrient uptake (Table 4). Higher harvest index was observed in Rampur Composite than Rampur Hybrid 2.This might be due to higher foliage biomass of Rampur Hybrid 2 than Rampur Composite. The harvest index was increased with increased N levels. Application of 90:60 kg P2O5:K2O ha-1 and 240 kg N ha-1 on Rampur Hybrid 2 gave highest net returns and benefit: cost ratio. For Rampur Composite, application of 60:40 kg P2O5:K2O ha-1 and 180 kg N ha-1 gave comparatively higher net return and benefit: cost ratio.

Conclusion
From the results of this experiment we concluded that for higher grain yield and economic net return 240:90:60 kg N:P2O5:K2O ha-1 can be applied for hybrid maize “ Rampur Hybrid 2” and for open pollinated variety “ Rampur Composite” 180:60:40 kg N:P2O5:K2O ha-1 can be applied on sandy loam soil at Chitwan valley condition of Nepal.

Acknowledgements
We would like to thank the Dr. K.B. Koirala maize coordinator who supported to conduct this experiment. We acknowledge CSISA Project Nepal for partial financial support during conducting this study. We would like to thank H.L. Bohora for his continuous help during field and lab work of this experiment.

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