The determination of plant density on dry matter accumulation, grain yield and yield components of four maize hybrids

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1 International Journal of Agriculture and Crop Sciences. Available online at IJACS/2013/5-2/-114 ISSN X 2013 IJACS Journal The determination of plant density on dry matter accumulation, grain yield and yield components of four maize hybrids Mehdi sadeghi Department of Agronomy, Dezful Branch, Islamic Azad University, Dezful, Iran Corresponding author ABSTRACT: The effects of plant density on dry matter accumulation, grain yield and yield components of four maize hybrids were evaluated. The experimental design was split plot format based on a randomized complete block with three replications. The study was conducted of Islamic Azad University of Dezful (Iran) farming research station in 20. The main factors were 4 levels of hybrids (Ks.c04, Ks.c00, K and K4) and plant densities,, and plants m -2 were used as sub-plot. The result showed with the increasing plant density of the whole hybrids increased amount of redistribution of dry matter. Because of increasing plant density were shade leaves high up on leaves and accelerate aging and was reduced its current photosynthesis. The maximum redistribution was obtained in hybrid KSC04 and plant density. Results showed that the hybrid, density and their interactive on grain yield, total dry matter, 00 seed weight and harvest index were significant. However, the number of rows per ear was not affected significantly by the plant density. Hybrid of Ks.c04 had the highest grain yield (450 kg ha -1 ) due to greater leaf area index and its delayed durability compared to other hybrids. Highest grain yield for the same hybrid was obtained at plant density of plants m -2. Both Ks.c00 and Ks.c04 hybrids at plant density of plants m -2 reached their maximum grain yield and increased density in the grain yield and yield components. Therefore, the combination of KS.c04 hybrid at plant density of plants m -2 was the best option to achieve the highest grain yield. Keywords: Grain yield, Plant density, Redistribution, Yield component. INTRODUCTION Grain weight one of the yield components of the maize plant was genetically influenced characteristics of number of grains per ear, grain competition, grain filling period, grain filling rate, rate of dry matter accumulation and environmental conditions before and after the anthesis (Lopez, et al,200). Stress conditions such as high density can be due to decreased photosynthesis due to leaf shading on each other and increased storage dry materials (Dwyer,et al.,11). Ehdaei et al., (2006) reported that high density has accelerated aging leaves and reduced photosynthesis rate and in turn stimulates the redistribution of dry materials stored in the grain (Ehdaie, et al. 2006). Schuler and Vestage (14) stated that the potential of the plant in accumulated amount of dry matter in vegetative organs necessarily mean high Potential not redistribute this material and factors such as the capacity of grain one of the key importance in redistributing material from vegetative organs to grain (Schussler and Westage, 14). The response of maize hybrids (zea mays L.) to plant population is different. Increased plant density results in higher grain yield per unit area (Sangio, et al., 2002). Tokatilids (2004) reported that improving grain yield due to increased plant population was achieved on a narrow spectrum (Tokatlidis and Koutroubas, 2004). Grain yield results from the increased pollen-to-silking interval and the fallowing barrenness reduced at higher plant population (Borras, et al., 2003). Higher grain yield produced due to higher plant density (Fulton. and Hokalipour, 20). Griesh (2001) reported that plant population densities from 5 to 5.6 plants m -2 were considered optimal (Grish and Yakut, 2001). However Rahmati (200) reported that the optimal density for acquiring higher corn grain yield was.5 plants m -2 (Rahmati, 200). Other researches (Danial, 2003) indicated that optimal plant density ranged from 5 to plants m -

2 Intl J Agri Crop Sci. Vol., 5 (2), -114, (Danial, 2003). Greater plant densities result in lower yields due to of competition for water, light and nutrients between plants (Sarlangue, 200). Response of Maize to plant density in row is more than row space. More densities lead to low rates of seed production as a result of competition for light and humidity (Turget, 2005). Maize grain yield per unit area shows a curvilinear response to plant population. For each production system, there is a population that optimizes the use of available resource, allowing the expression of maximum attainable grain yield in that environment (Cox, 2001). The ideal plant number per area will depend on several factors, such as water availability, soil fertility, hybrid maturity group and row spacing (Hashemidezfuli and Herbert. 12). Tollenear, et al, (1) reported that the late maturity hybrids are less sensitive to plant density (Tollenear, et al, 1).The higher height of plant at grain filling, the lower sensitivity to plant density (Berzsenyi and Dang., 2006). Timl et al, (2001) stated that hybrids with high grain filling period of more leaf area and leaf area index were correlated with grain yield (Timl et al, 2001). The objectives of this study were to evaluate the impact of different plant densities of maize hybrids on dry matter accumulation, yield and yield components. MATERIALS AND METHODS A field excrement was conducted at Dezful Research Farm of Azad University Khozestan, Iran (32º22 N latitude, 4º32 E) in 200 growing season. Soil ph was.5 and soil texture was clay loamy. This research was arranged as split plot design based on randomized complete block design with three replications. Main plots were assigned to hybrids of corn (Ks.c04, Ks.c00, K4 and k) and subplots to plant population densities (,. and plants m -2 ). Prior to seed sowing 0 kg ha -1 phosphorus in form of super phosphate triple and 250 kg ha -1 nitrogen in form of urea were broadcasted and incorporated into the soil. Fifty percent of urea was used at sowing time and residual was applied as top dress at 4-6 leafy stage. Corn seeds were disinfected and sown by hand on July. Irrigation was performed after sowing. Plots were kept free of weeds, insects and diseases. The plots were meter long and consisted of eight rows, 0.5 m apart. The space between blocks was 2 m and between each plot was 1 m was apart. Samples consisted of a 2 m 2 area of center of row of each plot after leaving two rows in the border areas were hand harvested at physiological maturity stage. The six ears were separated in order to determine the seed yield and yield components. Random samples were taken from each plot to determine seed and straw moisture, seed yield, total dry matter and seed dry matter. These samples were Oven dried at 2º C for 4 hours (1). Three ears were harvested at each sampling, and seeds from each ear were separated and each separately dried at 2 C for 4. Physiological maturity and final harvest at the end of the yield with yield components were calculated (Borras, et al., 2003). In order to measure the redistribution of dry matter of appearance time Tassel each week, three plants were harvested and determinates the dry weight relations were calculated amount and efficiency of redistribution (Ehdaie, et al and Lopez, et al, 200). Amount of redistribution (g.m-2) = Maximum dry matter in reproductive Dry weight at physiological maturity The Portion redistribution (%) = the amount redistribution/ Grain yield 0 The Efficient redistribution= the amount redistribution/ Maximum dry weight of reproductive 0 The data was analyzed using the SAS (, 1) software. When F-test was significant at P<0.05 level, Duncan s multiple range test was used to separate the means. RESULT AND DISCUSSION Amount redistribution of total dry matter The effects of hybrid, plant density and their interactive effects on amount redistribution total dry matter were significant (Table 1). Mean of comparison of total dry matter showed that Ks.c04 and Ks.c00 hybrids had the highest redistribution of total dry matter of plants and g m-2 respectively and the lowest total dry matter and.1g m-2 for k4 and k hybrids respectively (Table 2). Genetic differences between hybrids such as leaf area index, plant height and maturity could lead to differences in the amount of dry matter redistribution. It seems to be higher dry matter production and grain yield in hybrids more than 04 leading part in the redistribution (Austin, 10). The researchers reported that high photosynthetic capacity in Ks.c04 hybrids could lead to an increased rate of late was their remobilization (Schussler and Westage, 14).The lowest and highest of amount redistribution total dry mater were obtained at and plants m and g m-2 respectively (Table 2). The interactive effects plant density and hybrids showed that all hybrids at plant density of plants m-2 1

3 Intl J Agri Crop Sci. Vol., 5 (2), -114, 2013 had the highest amount redistribution (Table 3). Plant density increased light interception into the plant canopy was lower and thus causing environmental stress that the increased in the redistribution of dry matter. Reported that increasing redistribution of dry matter under high density was observed in many crop. (Austin,10 and Ehdaie, et al. 2006) Results of other researchers showed that with increasing plant density increased redistribution of dry matter and there was a significant positive correlation (Dwyer,et al.,11). Portion redistribution of total dry matter The effects of hybrid, plant density and their interactive effects on Portion redistribution total dry matter were significant (Table 1). Mean of comparison of Portion redistribution showed that Ks.c04 and k4 hybrids had the highest Portion redistribution of total dry matter of plants 1. and 1.5 percentages respectively and the lowest Portion redistribution of total dry matter 1.2 and 15.2 percentage for Ks.c00 and k hybrids respectively (Table 2). The results showed that interactive effects in the plant density of plants m-2 in SC04 had the highest Portion redistribution, but the hybrids k in the density of plants m-2, had the lowest Portion redistribution (Table 3). Reported that the redistribution Portion dry matter increased under environmental stress (Ehdaie, et al and Schussler and Westage, 14). Efficient redistribution of total dry matter The effects of hybrid, plant density and their interactive effects on efficient redistribution total dry matter were significant (Table 1). Mean of comparison of efficient redistribution total dry matter showed that Ks.c04 and Ks.c00 hybrids had the highest efficient redistribution of total dry matter of plants 14 and 13. g m-2 respectively and the lowest efficient redistribution total dry matter 11.5 and.5 g m-2 for k4 and k hybrids respectively (Table 2). The lowest and highest of efficient redistribution total dry mater were obtained at and plants m and 13.2 g m-2 respectively (Table 2). The interactive effects plant density and hybrids showed that all hybrids at plant density of plants m-2 had the highest efficient redistribution (Table 3). Other researcher reported that increasing the density of a substance produced by photosynthesis and other physiological sink was limited and therefore increased the allocation and redistribution of assimilates (Austin, 10, Ehdaie, et al and Schussler and Westage, 14). Crop yield The effects of hybrid, plant density and interactive affects their on grain yield were significant. Hybrid Ks.c04 had the highest grain yield (65.2 g m -2 ) than other hybrids (Table 1 and 2). Timl, (2001) showed a significant positive correlation between LAI with grain yield for hybrid S.c04 compared to other hybrids (Timl et al, 2001). Plant density plants m -2 (5.2 g m -2 ), the highest grain yield and plant density of plant.m -2 (41.3 g m -2 ) of had the lowest yield (Table 2). Increase in plant density of plants m -2 appropriate plant density and optimum use of space nutrition is without competition in plant canopy. The other Studies showed that Ks.c04 hybrid of grain yield was higher. The highest levels of grain yield in plant density were plants m -2. Due to the plant density of grain yield components like number of rows, number of grains per ear and grain weight than other higher plant density (Rahmati, 200 and Hokalipour, 20).Gozubenli, et al, (2004) experimenting on various plant densities observed corn grain yield increased with increasing plant density to plants per m -2 and higher densities of the competition for resources between plants decreased (Gozubenli, 2004). The interaction effects between hybrid and plant density on yield was significant. Mean comparisons revealed that the hybrid and plant density of plants m -2 with the Ks.c04 hybrid (13.5 g m -2 ) had the highest grain yield. The Ks.c00 hybrid is also the highest yield compared to the same density of plants m -2 (01.2 g m -2 ). While the two other hybrids means, k and k4 highest grain yield at the highest density of plants m -2 (Table 3). The reason for this is that the two hybrids (k and k4) a height of less than two hybrids (Ks.c04 and Ks.c00) and also they were early maturity, and therefore the hybrids to achieve high grain yield potential will require more plant density. Similar researches with increasing plant density to plant.m -2 increased grain yield (Echarte, 2000, Schussler and Westage, 14, Tollenear, 1 and Tokatlidis 2001). The effect of hybrid on the number of rows per ear was not significant. This subject coordinated to the genetic characteristics and showed genetic similarity in hybrids (Table1). Hashemidezfuli et al, (12) indicated that number of rows in ear was mainly genetically affected and the environment will be less affected. They also showed no significant effect on the trait number of rows per ear (Hashemidezfuli and Herbert. 12). The effect of plant density on the number of rows per ear was not significantly but related to the maximum plant density of plants m -2 (14.64) inverse plant density of plants m -2 (14.52), respectively. Hashemidezfuli, et al, (12) showed that the plant density of the number of rows per ear no significant effect on the trait and the genetic trait is more to the environment interaction effect plant density and hybrid on the number of rows per ear trait was not significant(hashemidezfuli et al.,12). Other research reported that the number of row in ear on interaction effects plant 111

4 Intl J Agri Crop Sci. Vol., 5 (2), -114, 2013 density and hybrid was not significant (Tokatlidis, 2011). Boarrs (2003) showed that higher plant density reduced number of rows per ear in whole hybrids their experiment (Borras, et al., 2003). Similarly Echart (2000) reported that reduced number of rows per ear with plant density to 14 plant m -2 (Echarte, 2000). Our results showed that effect hybrid and the interactive effect of hybrid and plant density of number of seed in row in number of seed in row was significant (Table 1). Hybrids of Ks.c04 and Ks.c00 had the highest (26.4 and 25.) number of seeds in the row and k (23.2) had the lowest number of seed per row (Table 2). The plant density effects on number of seed row showed that the plant density of (2.) and plants m -2 (23.4) were highest and lowest respectively (Table 2). Echart (2000) stated that increased plant density reduced the number of seed in rows (Echarte, 2000). Expressed that increasing plant density up to.5 plants m -2, seed number of ear and seed number per row should be lower than the number of rows per ear and 00 grain weight. Turget (2005) and Sarlango (200) suggested that increasing plant density reduced the number of seeds in rows, and this caused a significant decrease in yield (Sarlangue, 200 and Turget, 2005). Our result showed that the maximum number of rows of the Ks.c04 was plant density of plants m -2 (2.4) and the lowest hybrid of the k was at the plant density of plants m -2 (24.2). This suggested that the plant density was greater influence than the optimal number of seeds per row (Table3). Other researches reported the increasing density from 4 to plants m -2 reduced the number of seed rows per ear and reduce the number of rows of seed slowly(sarlangue, 200 and Turget, 2005). Results showed that the effects of hybrid, density and the interactive effects were significant on the 00 weight seed (Table1). The Ks.c04 and Ks.c00 hybrids had highest (3 and 2 g) and k hybrid had the lowest (25 g) 00 weight seed (Table2). The late maturity hybrid due to greater opportunities for growth and dry matter accumulation in the grain and the durability of the LAI of the seed weight than early maturity hybrids (Table 2). The most direct effect on grain yield had 00 weight seed and it can be reason highest grain yield in the Ks.c 04 and Ks.c 00 hybrids be compared to other hybrids. Rahmati (200) showed that the Ks.c 04 hybrid had greater seed weight compared to other hybrids (Rahmati, 200). Cox, et al,(2001) demonstrated that the hybrid with late maturity with increasing growing period, seed weight was higher than other hybrids and hence higher yield (Cox, 2001). The highest and lowest 00 seed weight were obtained of plant density of and plants m -2 (2 and 261 g) respectively. This can be due to competition among plants for resources environmental that with increasing plant density, seed weight was also reduced (Table 2). The results showed that interactive effects in the plant density of plants m -2 in SC04 and Ks.c00 had the highest yield, but the hybrids k4 and k in the highest density of plants m -2, had the highest yield. Because height of plant of two hybrids (k4 and k) was smaller than hybrid (Ks.c04 and Ks.c00) the greater plant density to achieve maximum yield (Table 3). Turget (2005) reported that early maturity hybrids with increasing plant density compare to lately maturity had the lowest 00seed weight (Turget, 2005). The effects of hybrid, plant density and their interactive effects on total dry matter were significant (Table 1). Mean of comparison of total dry matter showed that Ks.c04 and Ks.c00 hybrids had the highest total dry weight of plants and 15.3 g m -2 respectively and the lowest total dry matter 162. and 1.2g m -2 for k4 and k hybrids respectively (Table 2). Its seems that the longer growth periods was responsible for the higher total dry matter of these two hybrids. The lowest and highest of total dry mater were obtained at and plants m and g m -2 respectively (Table 2). The interactive effects plant density and hybrids showed that all hybrids at plant density of plants m -2 (Table 3). Cox et al (2001) indicated a positive correlation between yield and dry matter accumulation in different maize hybrids (Cox, 2001). Sarlango (200) and Turget (2005) reported that maximum dry matter was obtained at density of. plants m -2 (Sarlangue, 200 and Turget, 2005). Hybrid and plant density effects on harvest index were significant (Table 1). The Ks.c04 hybrid had highest harvest index (42.%) and other hybrids of Ks.c00, k4 and k were (42.2, 3.5 and 3., respectively). A positive correlation between economic grain yield and biological yield suggests that high index reflects the yield of each hybrid could be higher than the hybrid in the grain yield obtained from Ks.c04 hybrid. This can be due to a larger leaf area index and more leaf area durable as well as factors that increase the harvest index. The lowest harvest index (36.%) was obtained at high plant density of plants.m -2 and harvest index was higher (41.2%) for plant density of plants m -2. Reduction in plant density, higher harvest index, resulting from increased plant dry matter can be attributed to a negative relationship between biological yield and harvest index (Table 2). Interactive effects of harvest index were significant (Table 1). The Ks.c04 hybrid and the plant density of plants m -2 had the highest of harvest index. This can be due to a larger leaf area, leaf area index and yield strength compared to the optimal plant density, the same plants per m -2 can take advantage of all the environmental and economic yield benefits to be closer to its grain yield potential. The two hybrid k4 and k due to short plant height and more early maturity in its highest plant density is the same as plants per m -2 have been able to reach the highest harvest index and grain yield. These results confirm the notion that the more early maturity hybrids, leaf area and plant height is reduced to achieve higher yield, should be plant densities. Tollenear (2002) reported that the 112

5 Intl J Agri Crop Sci. Vol., 5 (2), -114, 2013 increase in maize grain yield due to biological yield of most of the increase (Tollenear, 2002). Boarrs (2003), Turget (2005), Sarlango(200) and Rahmati (200) stated that lower harvest index with increased plant density for maize hybrids. Our results reported clearly indicated that the hybrid ksc04 with plant density plants m -2 had the highest yield (Borras, et al., 2003, Rahmati, 200, Sarlangue, 200 and Turget, 2005). S.O.V Replicatio n Hybrid(H) Eroor1 Density(D) H D Eroor2 (%CV) df Table1. The effects of hybrids and different plant density on some ergonomic trait of maize hybrid Amount redistribution 13.2 ns * * 66.4 * Portion redistributi on ** **.625** Efficient redistributi on ** ** 4.6** Grain Yield 66.3 ns ** ** 4.5 * Total Dry Matter 43.1 * 4215.* * * * ** Weigh t 2. ns 55.6 * * 3.1 * Numb er of in Row 3. ns 4.5 ** ** *, **Significant at the 0.05 and 0.01 probability levels, respectively. 4.2 * Numb er of in Ear 0.32 ns 0.11n s ns 0.056n s Se ed 4.3 ns 65.5 ** ** 13.5 ** Harvest Index 2. ns 2.1 ** ** 0.43 * Treatment Hybrid Ks.c04 Ks.c00 K K4 plant Density (plant. m- 2 ) Table2. comparison of mean effect plant density on some agronomic traits of maize hybrids portion Efficient Grain Total Amount Number Number Harvest redistribution redistribution Yield Dry redistribution of Row of Index (%) (%) (kg ha - Matter (g m -2 ) (mg) 1 in Ear in Row (%) ) (g m -2 ) a b.1 d c 1. a 1.2 ab 15.2 b 1.5 a 14.0 a 13. a.3 b 11.5 b 2.3 a 22.0 b 20.0 c 21b c a b d c 14. a 14. a 26.4 a 25. a 23.6 c 24.5 b 15.6 a a c b 43.3 a 41. a 3. c 3.3 b 12. d 16.5 b 11. d 1.6 b d 2.4 a 15.4 c 40.6 a c 16.4 b 12.2 c 20. a 52.0 a 14.6 a 2.6 a 1. b a b 16.5 b 12. b 21.0 a b 22. b ab 3.3 b a 1. a 13.2 a 22.0 a 32.0 c 22. b 15. a 36.6 b For given means within each column followed by the same letter are not significantly (p<0.05) 00 (g) a 24.0 b c c 23.0 b 25.0 a 20.0 b c Hybrid Ks.c04 Plant Density (plant m- 2 ) Table3.Interaction effects of plant density on some agronomic traits of hybrids corn Amount portion Efficient Grain Number Number Total redistribution redistribution redistribution Yield of Row of Dry (g m -2 ) (%) (%) (kg ha -1 ) in Ear in Row Matter (g m -2 ) 14.4 bc 1.2 c 13.2 c 13.0 c 14. a 2.3 ab 200. c b 16. cd 13. bc a 14. a 2.4 a b 15.3 ab 1. bc 14.2 b bc 2.2 ab ab 162. a 1.2 a 14. a 5.0 b 2.1 b a Harvest Index (%) 41. ab 43.1 a 41.5 b 40.6 bc 00 (g) ab 30.0 a 2.0 b 23.0 b Ks.c c bc 15. ab a 16.5 cd 16.4 cd 1.1 c 1. b 13.2 c 13.6 bc 14.2 b 14. a bc ab 35.0 b c 14.6 a 14.6 a 2.1 b 2.2 ab 26. bc 26.3 bc c 24.2 b ab ab 40.3 bc 42. a 41.4 b 40.0 bc 2.0 b 30.0 ab 20.0 bc 23.0 bc K 0.2 f 4. f.1 ef e 14. f 14. e 14. ef 16.4 d.5 h.1 g.5 f. ef e 34.0 d 52.0 dc 4.0 dc 14.1 a 14.1 a 24.1 e 24.2 cd 24.3 cd 24.5 cd 13.2 e 16.6 d bc bc 36.2 d 3.2 c 36. c 3. bc 23.0 e 24.0 d cd 26.0 c K de 1.5 bc. ef 15.0 d 14.1 a 24.2 d d 36. c 125. d 1.6 bc 11.3 e cd 24.3 cd 14. d 36. c cd 1.4 bc 11. de 5.0 cd 24.5 cd bc 3. bc 13. c 1. b 12.2 d bc 14.3 a 24. c 20.4 bc 3. bc For given means within each column followed by the same letter are not significantly (p<0.05) cd 25.0 cd 20.0 c 26.0 bc 113

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