Response of Bt. Cotton to Different Nitrogen Doses and Plant Spacing

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1 Academia Journal of Agricultural Research 3(11): , November 2015 DOI: /ajar ISSN: Academia Publishing Research Paper Response of Bt. Cotton to Different Nitrogen Doses and Plant Spacing Accepted 19 th November, 2015 ABSTRACT Rafi Qamar 1,2 *, Allah DinoKalhoro 1, Abdul Rehman 2, Muhammad Ehsan Safdar 2, Muhammad Saqib 3, Hafiz Muhammad Rashad Javeed 4, Atique-ur- Rehman 5 and Amjed Ali 2 1 Agronomy section, Central Cotton Research Institute Sakrand, Sindh, Pakistan. 2 Department of Agronomy, University College of Agriculture, University of Sargodha, Pakistan. 3 Department of Agronomy, The Islamia University, Bahawalpur, Pakistan. 4 Environmental Sciences, COMSATS Institute of Information Technology, Vehari, Pakistan. 5 Department of Agronomy, Bahauddin Zakariya University, Multan, Pakistan. *Corresponding author. drrafi1573@gmail.com. Tel: Cotton, a major cash crop of Pakistan, is considered backbone of the national economy and efforts are required to raise the per hectare yield. A field experiment was conducted at Central Cotton Research Institute Sakrand to assess the response of new cotton cultivar Bt. CRIS-508 during Kharif season, 2012 and A randomized complete block design (RCBD) in split plot arrangement was used with four nitrogen doses [N 1 = 75kg N ha -1, N 2 = 100kg N ha -1, N 3 = 150 kg N ha -1 and N 4 = 200 kg N ha -1 ] in main plots and three plant spacing [S 1 = 15 cm, S 2 = 23 cm and S 3 = 30 cm] in subplots during 2012 and Nitrogen doses and plant spacing had significant effect on yield and yield components. Results revealed that during both the study years, N200 kg ha -1 significantly increased plant height, number of bolls per plant, boll weight, seed cotton yield (2.9 and 2.8 Mg ha -1 ) and nitrogen uptake compared than N50, N100 and N150 kgha -1 respectively. However, nitrogen uptake efficiency and nitrogen use efficiency was significantly lower in N200 kg ha -1 as compared with other nitrogen doses during both growing seasons. Cotton yield and yield components was increased by 30 cm plant to plant spacing while nitrogen uptake, nitrogen uptake efficiency and nitrogen use efficiency remained non- significant during 2012 and Plant height, number of bolls per plant, boll weight, nitrogen uptake, nitrogen uptake and use efficiency of nitrogen doses and plant pacing interaction remained non- significant while seed cotton yield showed significant response during both years. Key words: Nitrogen, plant spacing, cotton, yield. INTRODUCTION Cotton (Gossypium hirsutum L.) crop is a main cash crop and major source of foreign exchange. It plays a significant role in agriculture, agro-based industries and economic development of the country. It contributes 6.7% to the value added products in agriculture and 1.4% to gross domestic production (Government of Pakistan, 2013 to 2014). Currently, the area under cotton is 2.81 million hectares and total production is thousand bales with an average yield of 773kg ha -1 (Government of Pakistan, 2013 to 2014). Despite a higher yield potential and determined efforts of breeders and agronomists and average yield per unit area is well below other cotton producing countries of the world. Conventional methods of planting, poor quality seed, low seed rate and plant population, poor management practices, imbalanced nutrient management, weeds infestation and insect attack are the major constraints of low yield in cotton production at farmer s field. Nitrogen is one of the main vital nutrient and integral part of bio-chemical compounds (Marschner, 1986; Mengel and Kirkby, 1987). Nutrients unavailability affects the rate of photosynthesis, plant growth and supply of source to sink of the crop (Borowski, 2001). Nitrogen is the essential controlling nutrient to prevent the bolls and squares from abscission (Borowski, 2001; Perumai, 1999). Khan (1996) observed that nitrogen is a crucial element to attain higher yield of agricultural crops and exploit the crop potential. Ahmad (2000) reports that nitrogen is the main nutrient

2 Academia Journal of Agricultural Research; Qamar et al. 343 for cotton yield in irrigated areas. Ali and El-Sayed (2001) and Sawan et al. (2006) in their studies showed that earliness is reduced in cotton crop with increasing levels of nitrogen. In case of high nitrogen accessibility it resulted in excessive vegetative growth which delayed crop maturity and reduced yield by shifting the balance between vegetative and reproductive growth (Howard et al., 2001). In cotton, plant spacing has essential effects on the growth and yield attributes of the plant. Plant spacing is significant for attaining optimum crop growth and yield under irrigated conditions. Farmers used their traditional methods of planting to maintain plant spacing and density rather than variety requirement and hence, do not obtain high crop yield. Plant spacing of 30 cm increased plant height, number of bolls per plant and boll weight as compared to 10 and 20 cm respectively (Hussain et al., 2000). On the other hand, Muhammad et al. (2002) reported that boll weight was decreased by increasing plant population. The short stature plants can usually tolerate higher plant population without suffering significant yield reduction (Hake et al., 1991a). Suitable plant density enables the efficient use of applied fertilizers and irrigation (Abbas, 2000). At lower plant density, the fruiting branches are longer and a higher percentage of bolls are produced on outer fruiting branches.however, the first position bolls produced by high density are the biggest and best resulting in high yield (Bendnarz et al., 2005). Recognizing the immense significance of cotton crop, there is a need to increase the yield potential of the crop under the local environmental conditions of Sindh. Keeping in view the aforementioned discussion a research framework was made with the aim to evaluate the effect of yield potential of Bt. cotton under various levels of nitrogen and plant spacing under the agro-ecological conditions at Sakrand, Sindh. MATERIALS AND METHODS Study site The present study was performed at the experimental fieldof Central Cotton Research Institute under Agronomic Section, Sakrand, Sindh, to evaluate the productivity of Bt. CRIS-508 variety as affected by different nitrogen levels and plant spacing during Kharif seasons, 2012 and Experimental design and cultural practices A randomized complete block design (RCBD) in split plot arrangement with three replications that has plot size of 6.0 m x 3.0 m. Five levels (N l = 50 kg ha -1, N 2 = 100 kg ha -1, N 3 = 150 kg ha -1, N 4 = 200 kg ha -1 ) were randomized in the main plots while three plant spacing (S l = 15 cm, S 2 = 23, S 3 = 30 cm) applied in subplots. After the harvesting of wheat crop the land was prepared for cotton by giving two dry ploughings with disc plough followed by clod crushing to achieve fine seed bed. The soil of the experimental field was clay loam in texture under mono-cropping system. Cotton variety Bt. CRIS-508 was sown on 8 th of May, 2012 and 2013 with single row hand drill in 75 cm apart rows using seed rate of 20 kg ha -1. Phosphorus at 60 kg ha -1 and prescribed doses of nitrogen was applied as single super phosphate and urea, respectively. The entire phosphorus and half of the nitrogen was side dressed at sowing while the remaining half nitrogen was top dressed with first irrigation. All other agronomic practices were kept uniform for all treatments. Development and agronomic parameters of cotton Development and agronomic parameters of cotton including plant height (cm), average bolls per plant, average boll weight (g), 100-cotton seed weight (g), nitrogen uptake (kg ha -1 ), nitrogen uptake efficiency (kg kg -1 ), nitrogen use efficiency (kg kg -1 ) and seed cotton yield (Mg ha -1 ) were recorded. Ten plants were selected to record plant height, average bolls per plant and average boll weight. Three samples of 100 seeds were taken at random from each plot to record 100 cotton seed weight. The seed cotton yield was recorded on per plot basis and converted to kg ha -1. Nitrogen uptake efficiency and nitrogen use efficiency was calculated according to the procedure described by Reynolds et al. (2001). Statistical analysis Data collected was analyzed statistically by applying Fisher s analysis of variance technique. Least significant difference (LSD) test was employed at 5% probability level to test the significance of the treatments means (Steel et al., 1997). RESULTS Nitrogen doses and plant spacing had significant effects on Bt. cotton growth and yield parameters (Table 1 and Figure 1). In 2012 to 2013 growing season, N 200 had significantly higher plant height than N 50while plant height of N 150 and N 100 was at par with N 200 (Table 1). The N 200 had 10 and 12% higher plant height than in N 50 during 2012 and 2013 respectively. During both growing seasons, N 200 had significantly higher average bolls per plant than N 50 and N In 2012, N 200 had 19 and 16% higher average bolls per plant than in N 50 andn 100. Similarly, average bolls per plant of N 200 were 21 and 15% higher than in N 50 and N 100 during the 2010 to 2011 growing season. Average bolls per plant of N 150 and N 100 were at par with N 200. In both years of

3 Academia Journal of Agricultural Research; Qamar et al. 344 Table 1. Effect of different nitrogen doses and plant spacing on growth and yield components of Bt. cotton (Data over 2012 and 2013 growing seasons). Treatments Parameters Plant height (cm) Number of bolls plant -1 Boll weight (g) 100-cotton seed weight (g) Nitrogen uptake (kg ha -1 ) Nitrogen uptake efficiency (kg kg -1 ) Nitrogen use efficiency (kg kg -1 ) Nitrogen doses (kg ha -1) N 1 = ab ab 25.5 b 23.8 b 2.8 ab 3.1 b 5.95 d 5.92 d d d 0.85 a 0.83 a a a N 2 = a a 26.3 ab 25.5 ab 2.8 ab 3.2 ab 6.42 c 6.40 c c c 0.72 b 0.70 b b b N 3 = a a 29.3 a 28.2 a 3.0 a 3.5 a 7.13 a 7.11 a b b 0.55 c 0.53 c c c N 4 = a a 31.4 a 30.0 a 3.2 a 3.7 a 6.69 b 6.67 b a a 0.41 d 0.39 d d 8.27 c LSD p < Plant spacing (cm) S 1 = ab ab 27.5 ab 25.5 c 2.8 b 3.3 ab 6.31 b 6.25 b S 2 = a a 28.1 a 26.8 b 3.0 a 3.4 a 6.51 b 6.49 b S 3 = a a 28.9 a 28.4 a 3.1 a 3.5 a 6.80 a 6.78 a LSD p < NS NS NS NS NS NS Interaction (N x PS) NS NS NS NS NS NS NS NS NS NS NS NS NS NS Any two means not sharing a letter in common differ significantly at 5% probability level. study, N 200 had significantly higher average bolls weight than N 50 and N 100. In 2012, N 200 had 13% higher average bolls weight than in N 50 andn 100. Similarly, average bolls weight of N 200 was 16 and 14% higher than in N 50 and N 100 during the 2010 to 2011 growing season. In 2012 and 2013 growing seasons, N 150 produced 6, 10 and 17% more 100- cotton seed weight than in N 200, N 100 and N 50, respectively. During both years, N 200 produced the 9, 18 and 29% more nitrogen uptake than in N 150, N 100 and N 50, respectively. In both seasons, N 50 had the highest nitrogen uptake efficiency and use efficiency of Bt. cotton as compared with N 100, N 150 and N 200. In 2012 and 2013, Bt. cottonseed cotton yield was significantly higher (2.9 and 2.8 Mg ha -1 respectively) in N 200 followed by N 150 (2.8 Mg ha -1 and 2.6 Mg ha -1 ) as compared with N 100 and N 50. N 200 gave 14 to 17% higher seed cotton yield as compared with N 100 and N 50 during 2010 to 2011 growing season. Plant spacing significantly influenced the growth and yield of Bt. cotton in both growing seasons (Table 1). Significantly, maximum plant height of cotton was noted in S 3 that were 4% greater than the plant height of S 1 while S 2 was statistically at par with S 1 during the both years.similarly, number of bolls per plant and boll weight was higher in S 3 than S 1 trend and remained same during both years and S 2 was at par with S 3. During both growing seasons, 100-cotton seed weight of S 3 was 4 and 7% significantly higher than S 2 and S 1 while S 1 was statistically at par with S 2. In both years of study, plant spacing had no significant effect on nitrogen uptake, nitrogen uptake efficiency and nitrogen use efficiency. Seed cotton yield during 2012 and 2013 was significantly higher in S 3 that was 11% greater than in S 1 while S 2 was statistically at par with S 3 and S 1 respectively. In the year 2012 and 2013, nitrogen doses plant spacing interaction significantly influenced the seed cotton yield except plant height, number of bolls per plant, boll weight, 100-cotton seed weight, nitrogen uptake, nitrogen uptake efficiency and NUE (Table 1). DISCUSSION Significantly, higher plant height of Bt. cotton under nitrogen 200 kg ha -1 and plant spacing of 30 cm apart was reported due to availability of higher dose of nitrogen fertilization and wider plant spacing that reduced the competition between plants which resulted in vigorous plant growth. These results are in line with the findings of Ali et al. (2009) and it is clear from the results that a similar picture appeared during the second year. The yield of cotton crop depends upon the number of bolls

4 Seed Cotton Yield (Mg ha -1 ) Seed Cotton Yield (Mg ha -1 ) Academia Journal of Agricultural Research; Qamar et al Effects Effects LSD p<0.05 Nitrogen Nitrogen 0.34 Plant Spacing Plant spacing 0.20 NxPS 0.11 N PS Seed cotton yield (Mg ha S1 S2 S3 0.0 N50 N100 N150 N200 Nitrogen Treatments Nitrogen treatments Effects Effects LSD p<0.05 Nitrogen 0.53 Plant spacing Plant Spacing 0.19 NxPS N PS 0.12 Seed cotton yield (Mg ha S1 S S3 0.0 N50 N100 N150 N200 Nitrogen Treatments Nitrogen treatments Figure 1. Effect of different nitrogen doses and plant spacing on seed cotton yield of Bt. cotton (Data over 2012 and 2013 growing seasons).

5 Academia Journal of Agricultural Research; Qamar et al. 346 per plant and boll weight. It is also reported that N 200 and S 30 produced higher number of bolls per plant and boll weight. Increase in nitrogen from 150 kg to 200 kg ha -1 and plant spacing from 23 to 30 cm resulted in significant increase in the number of bolls per plant and boll weight. This is due to the excessive vegetative growth of plant due to high rate of nitrogen and less plant competition. These results are in line with those reported by Siddiqui (2007) and Ali et al. (2009). They revealed that number of bolls per plant and boll weight was decreased with decrease in N fertilization and plant spacing. 100-cotton seed weight is the key factor contributing to seed cotton yield. Significantly, higher 100-cotton seed weight of cotton was observed in N 150 than N 200, N 100 and N 50. Moreover, higher 100-cotton seed weight was recorded in S 30 than S 23 and S 15. The minimum seed cotton weight was recorded when nitrogen was applied at 50 kg ha -1 having plant spacing of 15 cm. The cotton seed weight increased significantly with each increase in nitrogen level up to 150 kg ha -1 and decreased with the increase of nitrogen fertilization. These results are almost similar to the findings of El-Gahel et al. (1991). Nitrogen uptake, nitrogen uptake efficiency and nitrogen use efficiency were significantly affected by variation in amount of nitrogen applied. More nitrogen was taken up by the plants in case of N 200 where it was applied in maximum amount. Nitrogen uptake decreased significantly with decrease in rate of nitrogen application. On the other hand, nitrogen uptake efficiency and nitrogen use efficiency were higher in lower dose of nitrogen, which may be due to effective utilization of available nitrogen by the plants. Nitrogen uptake efficiency and nitrogen use efficiency decreased with increasing amount of nitrogen as there may be losses of nitrogen due to volatilization and leaching. Plant spacing had no significant effect on nitrogen uptake, nitrogen uptake efficiency and nitrogen use efficiency. Consistently, higher seed cotton yield was observed in N 200 and S 30 than in other nitrogen fertilization and plant spacing.the final yield is the function of combined effect of all the yield components under a particular set of environmental conditions. The perusal of the table indicated that N 200 produced higher seed cotton yield that was statistically at par with N 150 and N 100 while plant spacing of 30 cm gave maximum seed cotton yield and it was also statistically at par with 23 cm and higher than 15 cm plant spacing under study. The maximum seed cotton yield was found in higher nitrogen fertilization and wider plant spacing was due to maximum availability of nutrients and less plant competition which resulted in higher yield and yield components. Ali et al. (2009) reported that higher seed cotton yield in higher nitrogen fertilization and wider plant spacing was due to more efficient use of nitrogen fertilizerthan all other levels in boosting reproductive phases of the crop. Conclusion Cotton crop is the king of fiber crops and the most significant profitable crop which plays a crucial role in the economy of Pakistan. It is the most basic textile fiber crop and second most important oilseed crop in the world. It is the cash crop of Pakistan and makes a good fortune to the country in the form of foreign exchange. It can be determined from this study that for getting maximum seed cotton yield among different plant spacing and different nitrogen doses, 30 cm plant spacing with 150 kg of nitrogen per hectare are optimum for cotton crop under agroecological conditions of Central Zone of Sindh. This result shows that nutrients are accessible to the cotton crop at all growth phases by above combination, that is why, crop gives significant seed cotton yield as compared to other combination of plant spacing and nitrogen doses. ACKNOWLEDGEMENT The manuscript is part of agronomic research conducted in Central Cotton Research Institute Sakrand, Sindh and financially supported by Pakistan Central Cotton Committee, Pakistan. REFERENCES Abbas MA (2000). General Agriculture. Publisher Emporium Lahore, Pakistan. pp Ahmad N (2000). Fertilizer scenario in Pakistan policies and development. Proc. Con. Agri. Fert. Use NFDC, P&D Division, Government of Pakistan Islamabad. 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