IMPACT OF PLANT DENSITIES AND NPK FERTILIZATION ON GROWTH AND OPTIMUM ECONOMIC RETURN OF SUNFLOWER

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1 IMPACT OF PLANT DENSITIES AND NPK FERTILIZATION ON GROWTH AND OPTIMUM ECONOMIC RETURN OF SUNFLOWER ABDUL AZIZ KHAKWANI 1*, SHARIF NOOR 1, MUHAMMAD SADIQ 1, INAYAT ULLAH AWAN 1, MUHAMMAD MUNIR 2, MUHAMMAD SAFDAR BALOCH 1, GHAZANFARULLAH 1 and IMAM BAKHSH 1 1. Department of Agronomy, Faculty of Agriculture, Gomal University, Dera Ismail Khan - Pakistan 2. Frontier Agriculture, SOYL Division, Recommendations Department, Newbury, United Kingdom *Corresponding author: azizkhakwani2002pk@yahoo.com ABSTRACT A field experiment was conducted to study the response of sunflower hybrid (Hysun -33) to different plant densities (11.11, 5.5 and 3.7 plants m -2 ) and NPK levels (50:50:0, 100:100:50 and 150:120:100 kg ha -1 ) at the Faculty of Agriculture, Gomal University, Dera Ismail Khan during spring Growth and yield traits of sunflower such as days to flowering, plant height, disc diameter, 1000-seed weight, number of seeds disc -1, seed yield, biomass yield and harvest index were significantly (P 0.05) affected by planting densities and NPK levels. The highest plant height ( cm), seed yield ( kg ha -1 ) and biomass production (19736 kg ha -1 ) was recorded under the highest plant density (11.11 plants m -2 ) used in this experiment that received the highest fertilizer dose of 150:120:100 NPK kg ha -1. On the other hand, the head diameter, 1000 seed weight, and seeds head -1 were the lowest under lowest planting density (3.7 plants m -2 ) that received the highest fertilizer dose. It is important to note that the highest benefit-cost ratio (BCR = 3.9) was obtained with highest planting density (11.11 plants m -2 ) and highest fertilizer dose (150:120:100 NPK kg ha -1 ). Based on this data plants m - 1 plant density and 150:120:100 kg ha -1 NPK fertilizers are recommended to get the highest yield and net return of sunflower under the agro-climatic conditions of Dera Ismail Khan. Key words: Sunflower, Helianthus annuus, NPK levels, plant density, plant spacing. Citation: Khakwani. A. A., S. Noor, M. Sadiq, I. U. Awan, M. Munir, M. S. Baloch, Ghazanfarullah and I. Bakhsh Impact of plant densities and npk fertilization on growth and optimum economic return of sunflower. Sarhad J. Agric. 30(2): INTRODUCTION Sunflower (Helianthus annuus L.) is cultivated in Pakistan for edible oil purpose. Since its introduction, the area ( m ha) and production ( m tonnes) with average yield of 1271 kg ha -1 are fluctuating due to low support prices and inefficient marketing system. This fluctuation in production has eventually affected the total (sunflower and canola) edible oil production of 560 m tonnes (Anonymous, ). Sunflower is drought tolerant and short duration ( days) crop and has a wider range of adaptability. Under Dera Ismail Khan s agro-climatic condition (arid region) it can be grown successfully twice a year as spring and autumn crop, both in irrigated and rain fed areas. Seeds of sunflower contain high oil contents (40-50%) and are also rich in protein (23%) (Grompone, 2005). Plants compete for water and space and sometimes for the attention of certain insects for pollination. In contrast to aboveground competition which primarily involves a single resource i.e., light, much of the competition among plants takes place underground where plants compete for a broad range of soil resources, including water and at least 20 essential mineral nutrients (Casper and Jackson, 1997). Belowground competition often reduces plant performance more than does aboveground competition (Wilson, 1988), and it is the principal form of competition occurring in arid lands or other systems with extremely low plant densities (Fowler, 1986). In order to achieve the greatest yield potential of a sunflower hybrid, the determination of its best planting density is of great significance. Planting geometry determines the distribution pattern of plants in a field. It affects solar energy interception, evaporation and water use efficiency of the crop. Proper spacing of plants makes plant canopy more effective in intercepting the gradient energy and shading effect on weeds (Saleem et al., 2008). Kazemeini et al. (2009) studied the interactive effects of deficit irrigation and two row spacing (50 cm and 75 cm) on growth, yield and oil yield of sunflower crop. They revealed the highest seed yield (458 g m- 2) and oil percentage (31.66%) from one irrigation and 75 cm row spacing. Similarly, Ali et al. (2011) in a field experiment evaluated the performance of two sunflower hybrids (Hysun-38 and FH-331) and four plant spacing (17.5, 20, 22.5 and 25 cm) between hills. Their results revealed that plant spacing of 22.5 cm gave the highest seed yield (1920 kg ha -1). Beg et al. (2007) investigated the effect of two planting densities (38,000 and 100,000 plants ha-1) in combination with two row to row spacing (50 and 75 cm) and four plant spacing (20, 25, 30, 35 cm) on agronomic traits of two open pollinated sunflower cultivars and revealed that the higher plant populations produced higher yield as compared to the lower populations.

2 Abdul Aziz Khakwani, et al. Impact of plant densities and npk fertilization on growth 158 Sunflower yield and yield associated parameters are greatly affected by plant densities and nutrient competition. Ali et al. (2012) observed a significant difference in days taken to flowering, seed formation, physiological maturity, and yield in two sunflower hybrids (S-278 and Hysun-33), when exposed to different plant densities and nitrogen levels. In another study, sunflower hybrid Hysun-33 produced higher seed yield (2318 kg ha -1) when plant density kept at 6.66 plants m-2 ( Yasin et al., 2011). Similarly, Süzer (2010) obtained higher seed yield by the application of 80 kg N ha-1 and 9.5 plants m-2 plant spacing. However, Osman and Awed (2010) recorded higher stem and head diameter, 1000-seed weight and seed yield by the application of nitrogen (140 kg ha-1), phosphorus (70 kg ha -1), and by maintaining 30 cm plant spacing. On the other hand, Bakht et al., (2010). Reported that combined application of NPK (150:100:100 kg ha -1) significantly enhanced leaf area index, crop growth rate, dry matter accumulation and seed yield of sunflower hybrids. Keeping in view the importance of NPK fertilizers and plant densities for economical return, an experiment was designed to determine the effect of various plant densities and NPK doses on growth and yield of sunflower hybrid under the agro-climatic conditions of Dera Ismail Khan. MATERIALS AND METHODS In order to evaluate the impact of plant density and NPK doses on growth and yield of sunflower hybrid, a field experiment was conducted at Faculty of Agriculture, Gomal University, Dera Ismail Khan during spring The experiment was laid out in two factorial randomized complete block design having four replications with a net plot size of 4.5 m 4.8 m (21.6 m2). The plant to plant space was maintained at 30 cm whereas row to row distance was kept 30, 60 and 90 cm respectively. The detail of treatments is given below: Treatments Planting densities N:P:K (kg ha -1 ) T 1 30 cm 30 cm (11.11 plants m -2 ) 50:50:00 T 2 30 cm 30 cm (11.11 plants m -2 ) 100:100:50 T 3 30 cm 30 cm (11.11 plants m -2 ) 150:120:100 T 4 30 cm 60 cm (5.55 plants m -2 ) 50:50:00 T 5 30 cm 60 cm (5.55 plants m -2 ) 100:100:50 T 6 30 cm 60 cm (5.55 plants m -2 ) 150:120:100 T 7 30 cm 90 cm (3.70 plants m -2 ) 50:50:00 T 8 30 cm 90 cm (3.70 plants m -2 ) 100:100:50 T 9 30 cm 90 cm (3.70 plants m -2 ) 150:120:100 Flood irrigation was applied to irrigate the field. Once the field was at field capacity level and suitable to work (watter condition), it was ploughed, disked, cultivated and rotor tilled. After seed bed preparation, the seeds of sunflower hybrid were sown 2 cm deep on hills (2 seeds hill -1 ) manually by dibbling with pure sand to protect the seeds from bird (sparrows) damage. After finishing the sowing, a light irrigation was applied to moist the soil to facilitate proper germination of seeds during last week of March, Phosphorus (SSP) and potash fertilizers (K 2 SO 4 ) were applied at the time of final land preparation while nitrogen (urea) was applied in two equal split doses i.e. first dose was applied at second irrigation and second dose was given at flowering stage. The plants were thinned by keeping one plant hill -1 and accurate plant population was maintained in all treatments until harvesting. Weeds were manually controlled by hoeing twice and five irrigations were applied whenever needed. Flowers were protected from parrots by beating the drums manually and using some reflectors as well. The rodents (Porcupines) were controlled by locally made iron cages, which proved to be very effective and 15 porcupines were captured during the course of experiment. Data on days to flowering, plant height, disc diameter, 1000-seed weight, number of seeds disc -1, seed yield, biomass yield, harvest index and benefit-cost ratio were recorded. The data analyzed according to analysis of variance technique through Statistix software, version 8.1 and subsequently least significance test (LSD) was applied for comparing and separation of treatment means. RESULTS AND DISCUSSION The data in Table 1 regarding days to flowering indicated non-significant (P>0.05) effects of plant densities and its interaction with NPK fertilizers, however, NPK alone has statistically significant (P 0.05) effect on this parameter. Maximum number of days to flowering (84.83) were recorded in lowest level of fertilizer (50:50:0 kg ha -1 ) while minimum (82.66) days to flowering were counted in 150:120:100 NPK kg ha -1 treatment which were statistically similar to 100:100:50 NPK kg ha -1 treatment (82.83 days). Ali et al. (2012) reported that sunflower hybrid S-278 flowered earlier at low nitrogen levels which are more or less similar to our findings where 2 days earlier flowerings occurs at low NP level (50:50:00 kg ha -1 ). However, in many herbaceous annual plants, flowering time is function of day length, temperature and gibberellins (Munir et al., 2010). In sunflower, day length and light integrals significantly affected flowering time (Baloch et al., 2010), therefore, two days earlier flowering of plants received highest NPK (100:100:50 and 150:120:100 kg ha -1 ) is not as significant as it would be under the influence of environmental factors.

3 Sarhad J. Agric. Vol. 30, No. 2, Table 1. Effect of planting densities and fertilizer levels on days to 50% heading of hybrid sunflower. 50:50: a 100:100: b 150:120: b LSD 0.05 Plant densities: NS Fertilizer Levels: 1.10 Interaction: NS followed by different letter(s) are statistically significant at 5% level of probability. It was observed that planting densities, fertilizer levels and their interaction significantly (P 0.05) affected plant height of sunflower (Table 2). The highest plant height ( cm) was observed under 5.5 plants m -2 density and was followed by plants m -2 ( cm) and 3.7 plants m -2 ( cm) densities. Similar findings were reported by Yasin et al. (2011). On the other hand, plants receiving the highest fertilizer dose (150:120:100 kg ha -1 ) were taller ( cm) and were followed by 100:100:50 NPK kg ha -1 ( cm) treatment. However, plants receiving the lowest NPK dose (50:50:0 kg ha -1 ) had cm height. As far as interaction of both factors was concerned, the maximum plant height ( cm) was recorded in plants m :120:100 kg ha -1 NPK combination and was closely followed by 5.55 plants m :120:100 kg ha -1 NPK combination (161 cm). Plants in higher planting densities etiolated because of the struggle for solar light reception. Similarly, higher levels of NPK enhanced vegetative growth of sunflower which leads to taller plants. These findings agreed with Osman and Awed (2010), Jahangir et al. (2006) and Bhilegaonkar et al. (1995). Table 2. Effect of planting densities and fertilizer levels on plant height (cm) of hybrid sunflower. 50:50: d c c 100:100: c b b b 150:120: a a b a c a b LSD 0.05 Fertilizer Levels: 3.03 Plant densities: 3.03 Interaction: 5.26 followed by different letter(s) are statistically significant at 5% level of probability. Production potential of sunflower plant is characterized by the size of its disc (head), which is an important yield contributing component. Although, it is more or less genetically controlled character but is also influenced by the environmental factors. Data regarding disc diameter (Table 3) indicated significant (P 0.05) difference among means of various planting densities, fertilizers and their interaction. Minimum number of plants m -2 (3.70) had largest disc diameter (16.15 cm). The second largest head under 5.5 plants m -2 (15.73 cm) was not significantly different than the first one under 3.7 plants m -2. The smallest (13.15 cm) disc diameter was measured in plants m -2 plant density The largest disc diameter (15.8 cm) was also observed when plants received the highest NPK (150:120:100 kg ha -1 ) dose. The second largest disc (15.38 cm) under 100:100:50 NPK kg ha -1 treatment was not significantly different than the first one. The significantly smallest disc diameter (13.86 cm) was under 50:50:0 kg ha -1 NPK dose treatment. Interaction of both factors showed that disc diameter was the highest (16.67 cm) in 3.70 plants m :120:100 kg ha -1 and 5.55 plants m :100:50 kg ha -1 NPK combinations which were statistically at par. Minimum disc diameter was observed in plants m -2 50:50:00 kg ha -1 NPK combinations. This may be due to ample light absorption and less nutrients competition between plants which subsequently increased assimilation rate and resulted in larger disc size. These results are in line with those reported by Osman and Awed (2010) who observed maximum disc size when sunflower received the highest level of NP. Similar findings were also reported by Yasin et al. (2011) and Nawaz et al. (2003). Table 3. Effect of planting densities and fertilizer levels on disc diameter (cm) of hybrid sunflower. 50:50: d bc ab b 100:100: c a ab a 150:120: bc ab a a b a a LSD 0.05 Fertilizer Levels: 0.89 Plant densities: 0.89 Interaction: 1.54

4 Abdul Aziz Khakwani, et al. Impact of plant densities and npk fertilization on growth 160 followed by different letter(s) are statistically significant at 5% level of probability. Planting densities, fertilizer levels and their interaction have statistically significant (P 0.05) effects on seed weight (Table 4). Significantly highest 1000-seed weight (52.67 g) was recorded in 3.7 plants m -2 plant density followed by 5.5 plants m -2 (45.18 g) plant density, however, significantly lowest 1000-seed weight (35.47 g) was observed in plants m -2 density. Plants receiving either 150:120:100 kg NPK ha -1 or 100:100:50 kg NPK ha -1 produced g and 45.0 g of 1000 seed weight and were not statistically different from each other, however, application of 50:50:0 kg NPK ha -1 depicted significantly lowest (41.01 g) 1000-seed weight. Interaction of plant densities and fertilizer did indicate that the highest (54.27 g) 1000-seed weight was achieved by 3.7 plants m :120:100 kg ha -1 NPK combination, which was statistically similar to 3.7 plants m -2 50:50:00 kg ha -1 NPK combination (51.95 g) and 3.7 plants m :100:50 kg ha -1 NPK combination (51.17 g). The minimum number of plants in wider space and high NPK levels are believed to turn plants more efficient which increased 1000-seeds weight. These results agreed with Tenebe et al. (2008), Beg et al. (2007), Ali and Osman (2004) and Ruffo et al. (2003). Table 4. Effect of planting densities and fertilizer levels on 1000-seed weight (g) of hybrid sunflower. 50:50: e bc a b 100:100: d bd a a 150:120: cd b a a c b a LSD 0.05 Fertilizer Levels: 2.72 Plant densities: 2.72 Interaction: 4.71 followed by different letter(s) are statistically significant at 5% level of probability. Analysis of data showed that planting densities and fertilizer levels had independent but significant (P 0.05) effects on number of seeds disc -1, whereas their interaction was statistically non-significant (Table 5). Significantly highest number of seeds disc -1 (1138.5) were counted in 3.7 plants m -2 plant density and were followed by 5.5 plants m -2 density (986). However, the significantly lowest number of seeds disc -1 (747.9) were found in plants m -2 density. Plants receiving either 150:120:100 kg NPK ha -1 or 100:100:50 kg NPK ha -1 produced and seeds per disc but the difference between the 2 was not statistically significant. However, the lowest number of seeds disc -1 (796.6) was counted in 50:50:0 kg NPK ha -1 treatment. Sufficient light interception and availability of major plant nutrients might be the best reason for the highest seed numbers disc -1. These results agree with Tenebe et al. (2008), Beg et al. (2007), Jahangir et al. (2006), Ali and Osman (2004), Ruffo et al. (2003) and Bhilegaonkar et al. (1995). Table 5. Effect of planting densities and fertilizer levels on number of seeds per disc of hybrid sunflower. 50:50: b 100:100: a 150:120: a c b a LSD 0.05 Fertilizer Levels: Plant densities: Interaction: NS followed by different letter(s) are statistically significant at 5% level of probability. It was observed that planting densities, fertilizer levels and their interaction significantly (P 0.05) affected the sunflower seed yield (Table 6). The significantly highest seed yield (3333 kg ha -1 ) was produced by plants grown closer to each other (11.11 plants m -2 ). The next significantly higher seed yield (2620 kg ha -1 ) was under 5.5 plants m -2 density. However, the significantly lowest seed yield (1767 kg ha -1 ) was recorded in 3.7 plants m -2 t density, Plants receiving the highest level of fertilizer (150:120:100 kg NPK ha -1 ) produced significantly highest seed yield (3304 kg ha -1 ). The second significantly higher seed yield (2715 kg ha -1 ) was under 100:100:50 kg NPK ha -1 treatment. However, the application of the lowest NPK dose (50:50:0 kg ha -1 ) resulted in significantly lowest seed yield (1700 kg ha -1 ). Interaction of both factors indicated that plants m :120:100 NPK kg ha -1 combinations gave significantly highest seed yield (4645 kg ha -1 ). However, the significantly lowest seed yield (1262 kg ha -1 ) was recorded in 3.7 plants m -2 50:50:00 NPK kg ha -1 combinations. Figure 1 also depicted a linear decreasing trend when plant density was decreased in all fertilizer application however maximum seed yield was achieved at highest plants density (11.11 plants m -2 ) and fertilizer application (150:120:100 kg ha -1 ). Seed yield is a function of combined effects of various yield components such as plant height, disc diameter, 1000-seed weight and number of seeds disc -1. The highest seed yield in

5 Sarhad J. Agric. Vol. 30, No. 2, densely populated treatment (11.11 plants m -2 ) with highest fertilizer level (150:120:100 or 100:100:50 NPK kg ha -1 ) may be due to more plants per unit area receiving ample plant nutrients that promoted all growth contributing parameters. Similarly, Bakht et al. (2010) obtained the highest sunflower seed yield (2813 kg ha -1 ) when they applied 150:100:100 NPK kg ha -1. Our findings also agreed with the outcome of Jahangir et al. (2006) and Islam et al. (2000). LSD Table 6 Effect of planting densities and fertilizer levels on seed yield (kg ha -1 ) of hybrid sunflower. 50:50: d d e c 100:100: b c d b 150:120: a b d a a b c Fertilizer Levels: Plant densities: Interaction: followed by different letter(s) are statistically significant at 5% level of probability. Seed yield (kg. ha -1 ) :50:00 100:100:50 150:120: Plant densities (cm) Fig 1. Effect of plant densities (30 30, 30 60, cm) and NPK fertilizer doses (50:50:00 ( ), 100:100:50 ( ) and 150:120:100 ( ) kg ha -1 ) on seed yield on hybrid sunflower. Significant differences (P 0.05) among biomass yields were observed among plant densities treatments, NPK levels and their interaction (Table 7). The significantly highest biomass yield (14824 kg ha -1 ) was observed in plants m -2 density and was followed by 5.5 plants m -2 density (12347 kg ha -1 ). However, the significantly lowest biomass yield (7968 kg ha -1 ) was measured in 3.7 plants m -2 density. The significantly highest biomass yield (13992 kg ha -1 ) was recorded under the highest level of fertilizer application (150:120:100 NPK kg ha -1 ) and was followed by 100:100:50 NPK kg ha -1 application (11868 kg ha -1 ). However, the significantly lowest biomass yield (9278 kg ha -1 ) was observed in 50:50:0 NPK kg ha -1 treatment. The highest dose of fertilizers increased all the growth parameters including plant height, leaves per plant, leaf size and see yield, which ultimately boosted the biomass yield compared to lower doses of NPK. Interaction of both factors indicated highest biomass yield (19736 kg ha -1 ) in plants m :120:100 NPK kg ha -1. The weight of dry sunflower stalk increased with an increase in plant density and NPK fertilizers which enhanced vegetative growth. The biomass yield is the result of plant height, number of leaves per plant, seed yield and number of plant per unit area. The more the vegetative growth, the more will be the dry matter accumulation, and hence more biomass yield per hectare would be produced. Present results are supported by the findings of Bakht et al. (2010) who reported that dry matter accumulation was significantly increased with increase in fertilizer levels. Our results are also in agreement with Bikas and Gajendra (2002).

6 Abdul Aziz Khakwani, et al. Impact of plant densities and npk fertilization on growth 162 Table 7. Effect of planting densities and fertilizer levels on biomass yield (kg ha -1 ) of hybrid sunflower. 50:50: de d 6641 f 9278 c 100:100: b bc 7792 f b 150:120: a c 9470 e a a b 7968 c LSD 0.05 Fertilizer Levels: Plant densities: Interaction: followed by different letter(s) are statistically significant at 5% level of probability. It was observed from the mean data presented in Table 8 that NPK fertilizer levels and their interaction with plant densities significantly (P 0.05) affected the sunflower harvest index however various planting densities alone showed non-significant effect on this parameter. Highest harvest index (23.5 and 23.10%) was recorded in NPK application of 150:120:100 and 100:100:50 kg ha -1 which were statistically at par however plants received 50:50:0 kg ha -1 NPK had minimum (18.61%) harvest index. Similarly, maximum harvest index was recorded in 3.7 plants m :100:50 kg ha -1 (25.29%), 5.5 plants m :120:100 kg ha -1 (25.26%) and plants m :100:50 kg ha -1 (24.29%) which were statistically not different. Highest harvest index might be due to minimum plants per unit area which received maximum balanced fertilizer, plenty of sunlight and space, as a result produced large discs with large seed size and maximum number of seed per disc. Table 8. Effect of planting densities and fertilizer levels on harvest index (%) of hybrid sunflower. 50:50: c c c b 100:100: a bc a a 150:120: ab a ac a LSD 0.05 Plant densities: NS Fertilizer Levels: 2.47 Interaction: 4.27 followed by different letter(s) are statistically significant at 5% level of probability. The economic viability of adapting different planting densities and NPK fertilizers management strategies in sunflower was determined through Benefit Cost Ration (BCR) (Table 9). Maximum BCR (3.9) was recorded in plants m :120:100 NPK kg ha -1 combination and was followed by plants m :100:50 NPK kg ha -1 combination (3. 3). Treatments 5.5 plants m -2 50:50:0 kg NPK ha -1 ( 2.8) and 5.5 plants m :120:100 NPK kg ha -1 (2.8) also proved economical as compared to other treatments. Moreover, the highest net-return was obtained from plants m :120:100 NPK kg ha -1 (Rs ha -1 ) and plants m :100:50 kg ha -1 (Rs ha -1 ) combinations. All these figures suggest that maximum planting densities (11.11 plants m -2 ) and highest NPK levels (150:1 20:100 and 100:100:50 kg ha -1 ) management strategies proved a financially viable option at existing costs and production prices. Therefore, the above mentioned options with highest BCR are most cost-effective for sunflower production under the agro-climatic conditions of Dera Ismail Khan. Table 9. Benefit-Cost Ratio (BCR) of hybrid sunflower. Treatments Fixed Variable cost ha -1 (Rs.) Plant densities cost N:P:K ha -1 N:P: Management (Rs.) K Seed Total expenditur e ha -1 (Rs.) Yield (kg ha -1 ) (Rs.) Income grain ha -1 (Rs.) Net income ha -1 (Rs.) cm - 50:50: cm - 100:100: cm - 150:120: cm - 50:50: cm - 100:100: cm - 150:120: cm - 50:50: cm - 100:100: cm - 150:120: Market price of sunflower seed per kg = Rs. 60 Fixed cost = Land preparation, sowing charges, irrigation, hand weeding, plant protection, harvesting, Miscellaneous BCR

7 Sarhad J. Agric. Vol. 30, No. 2, CONCLUSION AND RECOMMENDATIONS It can be concluded from the above study that planting density of plants m -2 with 30 cm apart row to row and 30 cm plant to plant distances along with maximum fertilizer dose of 150:120:100 NPK kg ha -1 provided highest seed yield of 4645 kg ha -1 of sunflower hybrid Hysun-33 (Figure 1). Therefore, this plant density and fertilizer application is recommended for the grower of Dera Ismail Khan to obtain maximum yield potential and higher net return per hectare of sunflower hybrid Hysun-33. REFERENCES Ali, A., A. Ahmad, T. Khaliq and J. Akhtar Phenology and yield of sunflower ( Helianthus annuus L.) hybrids as affected by varying plant spacing and nitrogen levels under semi-arid conditions of Sargodha, Punjab. Pak. J. Sci., 64: Ali, A., M. Afzal, I. Rasool, S. Hussain and M. Ahmad, Sunflower ( Helianthus annuus L.) hybrids performance at different plant spacing under agro-ecological conditions of Sargodha, Pakistan. Int. Conf. Food Engg. Biotechnol., 9: Ali, E.A. and E.B.A. Osman Effect of hill spacing fertigation using drip irrigation system in sandy calcareous soil on the productivity of some safflower genotypes. The 2nd International Conference for Development and the Environment in the Arab World, March 23-25, Assiut, Egypt. Anonymous Agricultural Statistics of Pakistan, Pakistan Bureau of Statistics, Statistics Division, Islamabad, Pakistan Bakht, J., M. Shafi, M. Yousaf and H.U. Shah Physiology, phenology and yield of sunflower (autumn) as affected by NPK fertilizer and hybrids. Pak. J. Bot., 42: Baloch, J.U.D., M.Q. Khan, M. Munir and M. Zubair Effects of different photoperiods on flowering time of facultative short day ornamental annuals. J. App. Hort., 12: Beg, A., S.S. Pourdad and S. Alipour Row and plant spacing effects on agronomic performance of sunflower in warm and semi-cold areas of Iran. Helia, 30: Bhilegaonkar, M.W., B.S. Ekshinge and B.G. Karle Effects of phosphorus, sulphur and boron levels on dry matter and grain yield of safflower. J. Maharashtra Agri. Uni., 20: 132. Bikas, M. and G. Gajendra Dry matter accumulation, nutrient uptake and water use efficiency of sunflower as affected by application of irrigation and nutrients. Ann. Agri. Res., 23: Casper, B.B. and R.B. Jackson Plant competition underground. Ann. Rev. Ecol. Syst., 28: Fowler, N.L The role of competition in plant communities in arid and semiarid regions. Ann. Rev. Ecol. Syst., 17: Grompone, M.A Sunflower Oil. Bailey s Industrial Oil and Fat Products, Sixth Edition. F. Shahidi (ed.). John Wiley & Sons, Inc., New York, USA. Pp Islam, N.M., A. Kader and M. Z. Islam Response of hybrid and local varieties of sunflower to spacing and fertilizer levels. Bangladesh J. Agri. Sci., 27: Jahangir, A.A., R.K. Mondal, K. Nada, S. Afoze and M.A. Hakim Response of nitrogen and phosphorus fertilizer and plant spacing on growth and yield contributing characters of sunflower. Bangladesh J. Sci. Ind. Res., 41: Kazemeini, S.A., M. Edalat and A. Shekoofa Interaction effects of deficit irrigation and row spacing on sunflower (Helianthus annuus L.) growth, seed yield and oil yield. Afr. J. Agri. Res., 4: Munir, M., P., Hadley, J. Carew, M. Zubair, S. Adams, S.B. Hussain, J.U.D. Baloch, N. Hussain and M. Amanullah An appraisal of the use of reciprocal transfer experiments based on leaf number and flowering time: Assessing the stages of photoperiod sensitivity in different cultivars of Antirrhinum majus L. Pak. J. Bot., 42: Nawaz, N., G. Sarwar, M. Yousaf, T. Naseeb, A. Ahmed and M.J. Shah Yield and yield components of sunflower as affected by various NPK levels. Asian J. Plant Sci., 2: Osman, E.B.A. and M.M.M. Awed Response of sunflower ( Helianthus annuus L.) to phosphorus and nitrogen fertilization under different plant spacing at new valley. Assiut Uni. Bull. Environ. Res., 13:

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