Sunflower spring-planting yield as affected by plant density and cultivar in Shahrekord region

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1 Proceedings of The Fourth International Iran & Russia Conference 997 Sunflower spring-planting yield as affected by plant density and cultivar in Shahrekord region Mohammad Rafieiolhossaini 1 and Foroud Salehi 2 1- Instructor of Agronomy, College of Agricullure, Shahrekord University, Shahrekord, Iran. Phone: m_rafiee_1999@yahoo.com; 2- Academic staff of Agricultural and Natural resources Research Center of Chaharmahal va Bakhtiari, Shahrekord, Iran. Phone: foroud_salehi@yahoo.com Abstract Sunflower (Helianlhus annuus L.) is a major oilseed crop in Iran with an acreage of nearly 100,000 ha. In order to study the effects of genotype cultivars and plant density on seed yield and agronomic characteristics of sunflower, an experiment was conducted at the research farm, College of Agriculture, Shahrekord University, Shahrekord, Iran in years. Four plant density and three cultivars (Azargol, Armavirsky & Zaria) were used in a factorial arranged in a randomized complete block design with four replicates. The seeds were drilled in plots at row distances of 60 cm apart and 15, 18, 21 and 24 cm between plants within rows. The results indicated that there is no significant differences between the head diameter, head yield and grain yield of cultivars but seed oil percentage, seed number per head, plant height, one thousand grain weight and oil yield were affected by genotype cultivars significantly. Zaria had the least (45.2%) and Azargol had the highest (47.2 %) oil percentage between cultivars. Azargol had the highest oil yield (1330 kg ha -1 ) between cultivars. Zaria had the least (44.7 gr) and Azargol had the highest (52.3 gr) one thousand grain weight between cultivars. Plant population hasn t any outstanding effect on plant height, head diameter, head yield, seed number per head and grain weight but increasing in plant density leads to higher seed oil percentage, grain yield and oil yield. Oil percentage, grain yield and oil yield were affected by plant density significantly. Increasing plant population increased oil percentage, grain yield and oil yield. The results of this study revealed the necessity of conducting comprehensive studies to increase grain quality and quantity of sunflower. Keywords: Cultivar, Plant density, Sunflower, Yield and Yield components INTRODUCTION Sunflower (Helianthus annuus L.) is a major oilseed crop in Iran with an acreage of nearly 100,000 ha. Some oilseed sunflower hybrids have been recently developed in the country, which are adaptable for mechanized farming, but few researches have been conducted on these new semi dwarf hybrids. Previous investigations have been mostly carried out as yield trials of hybrid and nonhybrid cultivars (Gubbels and Dedio, 1989; Karami, 1973). Increasing sunflower population, generally, increases the seed yield to a certain level. Optimum population depends on cultivar, environmental and field management factors (Robinson et al.,1980; Weiss, 2000). Gubbels and Dedio (1986) reported that a population of 4.5 plants m -2 was optimum for Saturn, Modern 12, CMH 103 and MF 707 cultivars. In another experiment (Gubbels and Dedio, 1989) they also showed that seed oil percentage increased, but seed weight decreased with increasing population in MRS 34 and Sunwheat 101 cultivars and the optimum population was 6.0 plants m - 2 for Sun M20 and S94 cultivars. Narwal and Malik found that 5.5 plants m -2 was optimum for EC 9874 cultivar. They also showed that increasing population significantly increased unfilled seed and decreased seed oil percentage. Vijayalakshmi et al. and Villalobos et al. found population of 5.7 for Armaveric and more than 15.0 plants m -2 for SW 101 cultivars,

2 Proceedings of The Fourth International Iran & Russia Conference 998 respectively. However, Robinson et al. reported that higher population did not decrease the yield of USDA 894, 860 and 923 cultivars and Radford obtained populations ranging 5.0 to 10.0 plants m -2 for irrigated sunflower. Wade and Forman also showed a higher optimum population for semi dwarf hybrids. The aim of the present experiment was to evaluate the influences of plant population and cultivar on yield and yield components of sunflower cultivars as spring - planting in Shahrekord region. MATERIALS AND METHODS The experiment was conducted in Agricultural Experiment Station, College of Agriculture, Shahrekord University at years. Soil samples were taken up to 30 cm depth at four sites and then mixed. Nitrogen, phosphorus, and potassium in the soil were determined by Kjeldahl, Olsen and extraction with ammonium acetate methods, respectively. Land preparation consisted of relatively deep tillage, disking twice at right ang1e with each other, and furrows establishment. Experiments were conducted as a factorial arranged in a randomized complete block design with 4 replications at both years. Plots were 4 rows of 8 m 1ong. Cultivar was A factor (Azargol, Armavirsky & Zaria). The seeds of cultivars were drilled in rows at a row distance 60 cm apart and 15, 18, 21 and 24 cm between plants in a row which corresponded to plant populations of 11.1, 9.26, 7.94 and 6.94 plant m -2, respectively. The seeds were planted on May. Final plant population was achieved two weeks after planting. Irrigation was applied as necessary and the soil remained close to field capacity throughout the experiments. Weeds were controlled by hand 20 and 45 days after planting at both years. The heads of the two central plant rows of each plot, which were kept for final harvest, were covered with newspaper completely right after pollination to prevent birds attack. Seeds were harvested on September, excluding the extremes (50 cm on either side). Head diameter, seed number and weight per plant from five heads and seed yield (10% moisture) was determined. Seed oil percentage was determined according to NMR procedures. The data were statistically analyzed by MSTATC software program and means were compared by Duncan's multiple range test. RESULTS AND DISCUSSION Increasing plant population decreased head diameter due to competition for light and nutrients at both years as also indicated by others (Karami, 1973; Massey, 1971), but it was not significant. Maximum head diameter (11.1 cm) was obtained from 6.94 plant m -2 (Table 2). Higher plant population levels decreased seed number and weight per head (Table 2), however it was not significant. This was due to decrease in head diameter, which could have caused the abortion of the initiated florets. The larger the head, the higher the seed numbers. There were no significant interactions between plant population and cultivars for seed number and weight per plant at two years. However, seed number and weight were significantly higher at 2003 than 2002, which could be due to higher soil fertility and better weather conditions (Tables 1 and 2). Seed yield significantly increased with increasing plant population, but there were no significant differences between 9.26 and 7.94 plant m -2 (Table 2 and Figure 2) as indicated by others (Aein et al., 1998; Karami, 1973; Radford, 1978; Robinson et al.,1980). The highest seed yield (3270 kg ha -1 ) was obtained with 11.1 plant m -2. Interaction between plant population and cultivars was not significant for seed yields at two years. However, seed yield was significantly higher at 2003 than 2002 (Table 2, Figure 3). Increasing plant population increased oil yield mainly due to increase in seed yield and oil seed percentage (Table 2 and Figure 2), which confirms the results of other investigators (Gubbels and Dedio, 1986; Gubbels and Dedio, 1989; Narwal and Malik,

3 Proceedings of The Fourth International Iran & Russia Conference ; Zubriski and Zimmerman, 1974). Combined analysis over years showed that 2002 and 2003 years presented significant differences in head diameter, seed number and weight per plant, seed and oil yields. Therefore, head diameter, seed number per plant and seed oil yield were higher at 2003 due to higher temperatures for plant growth and its probably higher pollinators activity, and higher soil fertility level (Tables 1 and 2, Figures 1 and 2). The results indicated that there is no significant differences between the head diameter, head yield and grain yield of cultivars but seed oil percentage, seed number per head, plant height, one thousand grain weight and oil yield were affected by genotype cultivars significantly (Table 2). Zaria had the least (45.2%) and Azargol had the highest (47.2 %) oil percentage between cultivars (Table 2). Azargol had the highest oil yield (1330 kg ha -1 ) between cultivars (Table 2 and Figure 1). Zaria had the least (44.7 gr) and Azargol had the highest (52.3 gr) one thousand grain weight between cultivars (Table 2). In summary, these investigations showed that increasing sunflower plant population increased seed and oil yield up to 11.1 plant m -2, while decreased head diameter, seed number and weight per plant. Azargol was the best cultivar in this experiment. The results of this study revealed the necessity of conducting comprehensive studies to increase grain quality and quantity of sunflower. References Aein, A., S.A. Hashemi-Dezfuli and M.R. Ahmadi Study of plant population and different planting patterns on growth and yield of sunflower cultivars in Giroft. Fifth Iran Conger. Crop Prod. Breed. Sci., Karaj, Iran (in Farsi), p Association of Official of Analytical Chemists Official Method of Analysis, 11th Edition, secs Washington D.C., U.S.A. Gharavi, S.M., and M. Karimi Effects of plant density on seed yield and yield parameters of two oilseed sunflower cultivars in Eastern Isfahan region. Fourth Iran Conger. Crop. Prod. Breed. Sci., Isfahan, Iran, (in Farsi). p Gubbels, G.H. and W. Dedio Effect of plant density and soil fertility on oilseed sunflower genotypes. Can. J. Plant Sci. 66: Gubbels, G.H. and W. Dedio Effect of plant density and seeding dates on early and late maturing sunflower hybrids. Can. J. Plant Sci. 69: Karami, E Effects of nitrogen and plant density on seed yield and agronomic characteristics of sunflower. Agric. Coll. Exp. Sta. Rep. No.5, Shiraz University, Shiraz, Iran (In Farsi) 10 p. Massey, J.H Effects of nitrogen rates and plant spacing on sunflower seed yields and other characteristics. Agron. J. 63: Miller, B.C., E.S. Oplinger, R, Rand, J. Peters and G. Weis Effect of planting date and plant population on sunflower performance. Agron. J. 76: Narwal, S.S. and D.S. Malik Response of sunflower cultivars to plant density and nitrogen. J. Agric. Sci., Camb. 104: Radford, B.J Plant population and row spacing for irrigated and rainfed oilseed sunflowers (Helianthus annuus L.) on the Darling Downs. Aust. J. Exp. Agric. Anim. Husb. 18: Robinson, R.G., J.H. Ford, W.E. Lueschen, D.L. Rabas, L.J. Smith, D.D. Warnes and J. V. Wiersma Response of sunflower to plant population. Agron. J.72: Vijayalakshmi, K., N.K. Sanghi, W.L. Pelton and C.H. Anderson Effects of plant population and row spacing on sunflower agronomy. Can. J. Plant Sci. 55: Villalobos, F.J., V.0. Sadras, A. Soriano and E. Ferers Planting density effects on dry matter partitioning and productivity of sunflower hybrid. Field Crops Res.36:1-11. Wade, L.J. and J.W. Forman Density x maturity interaction for grain yield in sunflower. Aust. J. Exp. Agric. Anim. Husb. 28:

4 Proceedings of The Fourth International Iran & Russia Conference 1000 Weiss, E.A Oilseed Crops. Blackwell Sci. Ltd., London. 364p. Zubriski, J.C. and D.C. Zimmerman Effects of nitrogen, phosphorus and plant density on sunflower. Agron. J.66: Table 1. Mean monthly temperatures (growing season) and some soil properties Agricultural Experiment Station Months temperatures ( C): 21 May- 20 June June- 21 July July 21 August August- 21 September September- 21 October Soil properties: N (%) P (mg kg-1) K (mg kg-1) EC (ds m-1) PH

5 Proceedings of The Fourth International Iran & Russia Conference 1001 Table 2: Comparison of means of plant height, head diameter, head yield, Seed number per head, one thousand grain weight, oil percentage, grain yield and oil yield of sunflower at Shahrekord region in Factors of experiment Plant height (cm) Head diameter (cm) Head yield (gr) Seed number per head grain weight (gr) Seed oil percentage Grain yield (kg/ha) Oil yield (kg/ha) Year a 8.8 b 17.1 b b 39.2 b 46.4 a b b a 13.0 a 37.8 a a 58.9 a 46.4 a a a Cultivar Azargol b 10.6 a 15.9 a b 52.3 a 47.2 a 2809 a 1330 a Armavirsky a 11.2 a 17.6 a b 50.1 a 46.7 a 2554 a 1192 ab Zaria ab 11.0 a 17.7 a a 44.7 b 45.2 b 2623 a 1102 b Plant density (plant m -2 ) a 10.9 a 14.7 a a 49.2 a 47.3 a 3270 a 1548 a a 11.0 a 17.9 a a 47.0 a 46.6 ab 2770 b 1294 b a 10.8 a 16.6 a a 49.6 a 45.9 b 2372 bc 1088 c a 11.1 a 19.1 a a 50.5 a 45.7 b 2235 c 1022 c In each part, means within column that have the same letter are not significantly different at 5% level (DMR test).

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7 Proceedings of The Fourth International Iran & Russia Conference Oil yield Grain yield Yield (kg/ha) Azargol Armavirsky Zaria Cultivar Figure1. Effect of cultivar on grain and oil yield of sunflower in Shahrekord region Grain yield Oil yield 2500 Yield (kg/ha) Plant density (plant per m^2) Figure2. Effect of plant density on grain and oil yield of sunflower in Shahrekord region

8 Proceedings of The Fourth International Iran & Russia Conference Grain yield Oil yield 3000 Yield (kg/ha) Year Figure3. Effect of year on grain and oil yield of sunflower in Shahrekord region Head diameter (cm), 1000-grain weight (gr) and Head yield (gr) head diameter grain weight Head yield Year Figure4. Effect of year on head diameter (cm), 1000-grain weight (gr) and head yield (gr) of sunflower cultivars in Shahrekord region