Effect of different planting densities and fertilizer rates on corn yield and yield components under Northern Vietnam growing conditions

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Effect of different planting densities and fertilizer rates on corn yield and yield components under Northern

Vietnam growing conditions

L. Q. Tuong, N. T. Khoi, D. V. Quan, B. B. Thinh, B. D. Chung, N. C. Thanh

To cite this version:

L. Q. Tuong, N. T. Khoi, D. V. Quan, B. B. Thinh, B. D. Chung, et al.. Effect of different planting densities and fertilizer rates on corn yield and yield components under Northern Vietnam growing conditions. Ecology, Environment and Conservation, EM International, 2019, 25 (4), pp.1696-1702.

�hal-03040494�

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Copyright@ EM International ISSN 0971–765X

*Corresponding author’s email: buibaothinh.dvfu@gmail.com

Effect of different planting densities and fertilizer rates on corn yield and yield components under Northern Vietnam growing conditions

Le Quy Tuong¹, Nguyen Tuan Khoi², Duong Van Quan², Bui Bao Thinh^3*, Bui Danh Chung⁴and Nguyen Cong Thanh⁵

1Center for plant evaluation and seed testing and plant products in Vietnam, Hanoi city, Vietnam

2Faculty of Agronomy, Bacgiang Agriculture and Forestry University, Bac Giang City, Vietnam

3School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russia

4Faculty of Agronomy, Northeast College of Agriculture and Forestry, Quang Ninh, Vietnam

5Department of Science and International Cooperation, Bacgiang Agriculture and Forestry University, Bac Giang city, Vietnam

(Received 23 June, 2019; accepted 12 August, 2019)

ABSTRACT

Corn (Zea mays L.) is one of the vital cereals and grown all over the world as a major food source. Various studies on agricultural methods such as farming techniques, irrigation, fertilization, breeding have been conducted to increase corn yield. Planting density and fertilizer rate, in particular, are known and widely applied as the first method to increase corn yield. In this study, we observed the effect of planting densities and fertilizer rates on yield and yield components of NK4300 corn which was grown in northern Vietnam in the winter season. The experiment focused on density and fertilizer with a Split-plot arrangement having three replications. The results showed that the corn yield and yield components were significantly affected by the planting densities and fertilizer rates. Cob length, cob diameter, number of grain rows per cob, grain percentage per cob and 1000-Grain Weight varied considerably as the fertilizer rates and planting densities had changed. The number of grains per row was not affected by planting densities and fertilizer rates. The corn actual yield was influenced by different factors such as cob length, cob diameter, number of grain rows per cob, number of grains per row and 1000-Grain Weight. The actual yield of experimental treatments varies greatly from 40.27 quintals ha^-1 to 73.46 quintals ha^-1. The highest yield (73.46 quintals ha^-1) could be obtained when combining the planting density of D₂ (66 thousand plants ha^-1) with F₄ fertilizer rate (180kg N + 80kg P₂O₅ + 100kg K₂O) ha^-1.

Key words : Corn, Zea mays, Fertilizer rate, Planting density, Yield, yield component.

Introduction

Corn (Zea mays L.) originated from Central America, which is an important food crop that ranks in the third place among all cereals in the world after wheat and rice (Troyer, 1999; Molazem et al., 2010).

It is the main food source for many types of poultry,

industrial livestock and an essential source of in- come for farmers. Numerous essential human nutrients such as vitamin C, B1, B5, folic acid, lysine, selenium can be found in corn (Loy and Lundy, 2019).

These nutrients play an important role in carbohy- drate metabolism, support body functions as well as stimulate immunity against diseases for humans.

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QUY TUONG ET AL 1697 Selenium, for example, plays an active role in cancer

prevention (Mehdi et al., 2013). Currently, corn is also an important source of bioenergy (ethanol), which is considered as a solution to an energy short- age in the future (Patzek, 2004).

Population growth has put considerable pressure on the world’s agricultural production as demand for food has been increasing both in quantity and quality. Meanwhile corn planting area is decreasing due to urbanization (Wang, 2019). Complex climate conditions have affected the growth and development of corn (Farhangfar et al., 2015). However, thanks to advances in research and production, corn yield and area have been improved.

In addition to selecting highly tolerant corn vari- eties, farming methods play an extremely important role in agricultural production. Different variety grown in different ecological and climatic regions needs different farming methods. Planting density and fertilizer rate are two important factors in farming methods to increase crop yield (Yan et al., 2016).

If planting density is too thick, it will cause compe- tition among plants in terms of nutrition, light as well as create conditions for pests and diseases to develop (Williams et al., 1968). During the growth and development, corn plants need to absorb significant nutrients from the soil; otherwise, the pro- tein content of corn grains will be reduced and the quality of soil will be lower at the same time. There have been many studies on the effects of planting densities and fertilizer rates on crop productivity in many different ecological regions (Ughade and Mahadkar, 2015; Guo et al., 2016; Li et al., 2017).

Nevertheless, until now the effects of planting densities and fertilizer rates on yield and yield components of NK4300 corn grown in northern Vietnam in the winter season have not been fully reported. De- termining the appropriate planting densities and fertilizer rates will be helpful to ensure sufficient light and nutrients for the plants’ growth and development, thereby improving the resilience of the plants to increase yield and economic efficiency in each farming condition. This study aimed to ob- serve the effect of different planting densities and fertilizer rates on yield and yield components of NK4300 corn grown in northern Vietnam in the winter season. Statistics of yield components and actual yield were used to determine the appropriate planting densities and fertilizer rates for this corn variety.

Materials and Methods

Research Materials

NK4300 corn, provided by Syngenta Company (Vietnam), is a popular corn cultivar in Vietnam.

Urea nitrogen (46% N), Lam Thao Phosphate (16%

P₂O₅) and Potassium chloride (60% K₂O).The experiment was conducted in the 2017 winter season at the Maize Research Institute in Hanoi, Vietnam (21°05’17.0"N and 105°39’15.4"E).

Research method

The field experiment included density and fertilizer with a Split-plot arrangement having three replications. Fertilizer rates were in the main plots and planting densities were in the sub-plots. Each sub- plot consisted of four rows, 5.0 m long with sur- rounding protection fence. The fertilizer rates comprised 5 different formulas per hectare: F₁ (150kg N + 80kg P₂O₅+ 80kg K₂O),F₂ (150kg N + 80kg P₂O₅+ 100kg K₂O),F₃ (180kg N+80kg P₂O₅+ 80kg K₂O),F₄ (180kg N + 80kg P₂O₅+ 100kg K₂O) andF₅ (150kg N + 80kg P₂O₅ + 60kg K₂O) (control). Planting densities comprised 4 different formulas: D₁ (60 x 30 cm - 56 thousand plants ha^-1) (control), D₂ (60 x 25 cm - 66 thousand plants ha^-1), D₃ (60 x 22 cm - 76 thousand plants ha^-1) and D₄ (60 x 20 cm - 83 thousand plants ha^-1). There were 20 formulas based on combination of the planting densities and fertilizer rates:

D₁F₁, D₂F₁, D₃F₁, D₄F₁, D₁F₂, D₂F₂, D₃F₂, D₄F₂, D₁F₃, D₂F₃, D₃F₃, D₄F₃, D₁F₄, D₂F₄,D₃F₄, D₄F₄, D₁F₅, D₂F₅, D₃F₅and D₄F₅.

The soil was plowed, weed and crop residue of the previous crop cleaned. It was under thorough soil solarization dried, liming before being leveling.

All the soil was basally applied with animal manure and phosphate fertilizer. 2 to 3 seeds were sown for each hole. Trimming and additional seedling planting were to ensure proper density and number of plants. When the plant had 3 to 4 real leaves, it was ripped, weed cleaned trimmed to ensure 1 plant per hole; it was then applied additional fertilizer for the first time with 1/3 of nitrogen. When the plant had 7 to 9 real leaves, it was weed cleaned and applied additional fertilizer for the second time with 1/3 of nitrogen + 1/2 of potassium. By the tasseling period, 1/3 of the nitrogen + 1/2 of the remaining potassium were applied. The growth and development of corn plants were observed carefully for timely measures when needed. Watering and pre-

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vention of pests and diseases were conducted in a scientific way to ensure conditions for corn to grow.

Corn was harvested separately according to each formula when it is matured.

The yield components (10 cob in the experimental plots and calculated for average data): cob length; cob diameter; number of grain rows per cob;

number of grains per row; grain percentage per cob;

1000-grain weight (weighed twice, 500 grains each time, if the comparison of difference did not exceed 5%, take the average of the two weight); theoretical yield; actual yield. All the data were analyzed with analysis of variance (ANOVA) procedures using IRISSTAT 4.0. The mean differences were adjudged by Duncan’s Multiple Range Test (DMRT).

Results and Discussion

Yield is an important indicator to assess the impact of technical measures and farming conditions, to reflect the ability to grow, develop, and tolerate un- favorable conditions as well as to adapt to external conditions (Fischer, 2015). Corn yields are directly generated from yield components such as cob length, cob diameter, number of grain rows per cob, number of gains per row and 1000-grain weight (Gökmen et al., 2001). These factors are formed at

different times, have different rules and are affected by different conditions but they have an interrela- tionship. It is necessary to consider these factors to improve corn yield and quality. The effect of planting densities and fertilizer rates on corn yield components and actual yield are shown in Table 1, Table 2 and Table 3.

Cob length

Different fertilizer rates led to different cob length (Gul et al., 2015). The longest average cob length in fertilizer rate F₃ and F₄ was at 14.6 cm and the shortest one was at F₅ with only 13.6 cm (Table 1). The cob length tended to increase when the amount of fertilizer increased. Different planting densities caused different lengths of corn. It was recorded that the cob length gradually increased when planting density went up from 56 thousand plants ha^-1 to 76 thousand plants ha^-1 but it would decrease when planting density reached 83 thousand plants ha^-1. The cob length varied from 13.7 to 14.8 cm (Table 2).

Table 3 shows that the shortest cob length (12.9cm - 14.2cm) was at D₄ with different fertilizer formulas and the longest was found in D₃ (14.2cm - 15.2cm).

Similar effects of planting densities and fertilizer rates on cob length were reported by Gökmen et al.

(2001) in popcorn.

Table 1. Effect of fertilizer rates on corn yield and yield components

Formula Cob Cob Number of Number of Grain 1000-Grain Theoretical Actual

length diameter grain rows grains per percentage Weight yield yield (cm) (cm) per cob row per cob (%) (gram) (quintal/ha) (quintal/ha)

F₁ 14.2 b 4.22 a 13.63 a 30.99 b 62.56 305.5 83.52 56.69 b

F₂ 14.3 b 4.32 a 13.98 bc 31.48 b 62.71 307.2 86.98 55.93 b

F₃ 14.6 c 4.52 c 13.85 ab 31.37 b 63.80 305.8 85.85 58.94 bc

F₄ 14.6 c 4.62 c 13.70 a 31.43 b 63.65 307.5 84.62 61.10 c

F₅ 13.6 a 3.63 a 13.55 a 29.87 a 61.17 300.5 80.78 46.40 a

CV (%) 1.7 2.8 2.0 2.3 - - - 5.1

LSD_(0.05) 0.19 0.14 0.25 0.68 - - - 2.98

The average value with the same letters in one column is not significantly different at  = 0.05.

Table 2. Effect of planting densities on corn yield and yield components

length diameter grain rows grains percentage Weight yield yield

(cm) (cm) per cob per row per cob (%) (gram) (quintal/ha) (quintal/ha)

D₁ 14.4 b 4.44 c 14.28 d 30.79 a 68.38 314.8 80.20 62.31 c

D₂ 14.4 b 4.24 b 13.88 c 31.05 a 66.66 308.8 82.90 64.51 d

D₃ 14.8 c 4.14 a 13.62 b 31.18 a 60.84 303.8 88.24 50.94 b

D₄ 13.7 a 4.24 b 13.18 a 31.09 a 55.24 293.8 85.96 45.53 a

CV (%) 1.7 2.8 2.0 2.3 - - - 5.1

LSD_(0.05) 0.17 0.09 0.20 0.52 - - - 2.10

The average value with the same letters in one column is not significantly different at  =0.05.

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QUY TUONG ET AL 1699 Cob diameter

Like cob length, fertilizer rates were directly proportional to cob diameter. Cob diameter varied from 3.63cm to 4.62 cm. The biggest one belonged to F₄ at 4.62cm (Table 1). When planting density increased, the cob diameter decreased, ranging from 4.14 to 4.44cm. The biggest cob diameter at D₁was at 4.44 cm (Table 2). The variation of fertilizer rates and planting densities contributed to the differences in cob diameter. D₁with different fertilizer levels pro- duced the biggest cob diameter (Table 3). The formula D₁F₄gave the biggest cob diameter of 4.8 cm.

Number of grain rows per cob

Number of grain rows per cob depended on the cob diameter and grain size. This factor is mainly deter- mined by its cultivar and is dominated by environ- mental factors (Ashraf et al., 2016). Changes in fertilizer rates did not considerably affect number of grain rows per cob which fluctuated from 13.55 to 13.98 rows. The fertilizer level of F₂ achieved the largest number of grain rows at 13.98 rows and the smallest was in F₅ at 13.55 rows (Table 1). The

changes in planting density also led to changes in number of grain rows; the number of grain rows decreased gradually when the planting density increased. The number of grain rows fluctuated from 13.18 to 14.28 rows. D₁ (56 thousand plants ha^-1) has the largest number of grain rows reaching 14.28 rows (Table 2). The number of grain rows per cob of fertilizer rates combined with planting densities is differently but not significantly, ranging from 13.0 to 14.6 rows. The number of grain rows per cob was inversely proportional to the density at different fertilizer levels. The formula D₁F₃ and D₁F₄ recorded the largest number of grain rows per cob without significant difference. This result is consistent with published studies (Ashraf et al., 2016; Shahid et al., 2016).

Number of grains per row

Number of grains per row reflected number of pol- linated and fertilized flowers (Primack, 1987). It depended not only on the cultivar but also on the external conditions during tasseling period. This is an important indicator determining yield of the hybrid, which is the basis for proper seasonal arrangements Table 3. Effect of interaction between planting densities and fertilizer rates on corn yield and yield components

length diameter grain rows grains per percentage Weight yield yield (cm) (cm) per cob row per cob (%) (gram) (quintal/ha) (quintal/ha)

D₁F₁ 14.1 d 4.4 ef 14.2 bc 30.47 a 68.41 315 77.41 60.37 e

D₂F₁ 14.4 de 4.2 cd 13.8 ab 30.87 ab 67.25 310 82.31 67.27 ef

D₃F₁ 14.7 ef 4.1 c 13.5 ab 31.20 ab 60.22 305 87.79 53.87 cd

D₄F₁ 13.4 b 4.2 cd 13.0 a 31.40 ab 54.37 290 86.57 45.27 ab

D₁F₂ 14.3 de 4.5 fg 14.5 cd 30.73 a 68.63 315 79.36 62.63 e

D₂F₂ 14.5 ef 4.3 de 14.2 bc 31.73 ab 68.26 308 87.04 64.53 e

D₃F₂ 14.8 fg 4.2 cd 13.8 ab 31.67 ab 59.90 304 90.95 50.97 bc

D₄F₂ 13.5 bc 4.3 de 13.4 a 31.80 b 54.07 291 90.57 45.60 ab

D₁F₃ 14.4 de 4.7 hj 14.6 cd 31.27 ab 69.42 313 80.74 65.60 ef

D₂F₃ 14.8 fg 4.5 fg 13.8 ab 31.40 ab 67.78 308 83.70 68.01 ef

D₃F₃ 15.1 gh 4.4 ef 13.6 ab 31.53 ab 62.91 305 89.27 54.27 cd

D₄F₃ 14.0 d 4.5 fg 13.4 a 31.27 ab 55.09 294 81.94 47.90 ab

D₁F₄ 14.4 de 4.8 j 14.4 cd 31.67 ab 67.78 316 82.97 70.63 fg

D₂F₄ 14.7 ef 4.6 gh 13.8 ab 31.27 ab 66.31 309 89.45 73.46 g

D₃F₄ 15.2 h 4.5 fg 13.6 ab 31.53 ab 62.28 305 84.15 51.63 bc

D₄F₄ 14.2 de 4.6 gh 13.0 a 31.27 ab 58.24 285 81.58 48.63 ab

D₁F₅ 13.5 bc 3.8 b 13.7 ab 29.80 a 67.65 309 71.58 52.30 bc

D₂F₅ 13.8 cd 3.6 a 13.8 ab 30.00 a 63.69 306 78.94 49.27 bc

D₃F₅ 14.2 de 3.5 a 13.6 ab 29.93 a 58.90 301 83.76 43.97 a

D₄F₅ 12.9 a 3.6 a 13.1 a 29.73 a 54.45 280 78.84 40.27 a

CV% 1.7 2.8 2.0 2.3 - - - 5.1

LSD_(0.05) 0.34 0.17 0.40 1.01 - - - 4.70

The average value with the same letters in one column is not significantly different at  = 0.05.

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and appropriate technical measures (Shahid et al., 2016). Similar to number of grain rows per cob, number of grains per row was less variable at the fertilizer rates. The number of grains per row fluctuated from 29.87 to 31.48 grains. Fertilizer rate F₅ had the smallest number of grains per row (Table 1). The number of grains per row changed insignificantly when the planting densities changed, ranging from 30.79 to 31.18 grains. The largest number of grains per row was in D₃ (Table 2). When combining the planting densities and fertilizer rates, the number of grains per row had no enormous difference among the formulas, the smallest number of grains per row at F₅ with different planting densities was at 29.73 to 30 grains (Table 3). The results show that the number of grains per row was not affected by planting densities and fertilizer rates. This is consistent with the results of Gökmen et al’s study (2001).

Grain percentage per cob

Grain percentage per cob was the percentage of 10- cob-sample weight and 10-cob weight of each formula. When there was a change in fertilizer rates, the grain percentage per cob also changed and tended to increase in a direct proportion of the fertilizer level. The fertilizer rate F₅ had the lowest grain percentage per cob at 61.17% and the highest was at 63.80% in F₃. The increase in planting densities led to the decrease in the grain percentage per cob; the lowest was only 55.24% at D₄ (Table 2). For each fertilizer rate, when the planting density increased, the grain percentage per cob marginally decreased. The difference in grain percentage per cob in terms of combination of planting density and fertilizer rate was huge. D₁ with different levels of fertilizer had the highest grain percentage per cob from 67.65% to 69.42% (Table 3).

1000-Grain Weight

It is a vital indicator to show the properties of each cultivar. 1000-Grain Weight depended on the size of grains. The more grains a cultivar had, the higher its 1000-Grain Weight. This is the basis for determination of the yield of the cultivar. 1000-Grain Weight increased when the fertilizer rate increased, ranging from 300.5 to 307.5 grams. The highest 1000-Grain Weight was found in F₄ and the lowest was in F₅ (Table 1). Different planting densities led to different 1000-Grain Weight, which tended to decrease when there was an increase in density, ranging from 293.8 to 314.8 grams. D₁ had the highest 1000-Grain

Weight at 314.8 grams (Table 2). With the same fertilizer formula, 1000-Grain Weight tended to decrease as the planting density increased (Table 3). D₁ with different levels of fertilizer had the highest 1000-Grain Weight from 309 to 316 grams (Table 3).

Similar results were found in other studies (Thakur and Malhotra, 1991; Arif et al., 2010; Imran et al., 2015).

Theoretical yield

Theoretical yield is the maximum yield that a cultivar can achieve in a specific farming condition. This is also an indicator to assess the potential of a cultivar in each soil and climate condition and a certain level of cultivation. Whether theoretical yield is high or low depends on individual yield and planting density. Theoretical yield reflects the yield potential of the corn hybrid combination that can be achieved under certain conditions. It can be different among various fertilizer grounds ranging from 80.78 quintals ha^-1 to 86.98 quintals ha^-1. F₂ had the highest theoretical yield while the smallest was in F₅ (Table 1). The theoretical yield differences among the density levels were relatively huge from 80.20 quintals ha^-1 to 88.24 quintals ha^-1. D₃ density had the highest theoretical yield at 88.24 quintals ha^-1 (Table 2). In most fertilizer grounds with different density, theoretical yield tended to increase when the density increased. F₂combined with D₃ had the highest theoretical yield at 90.95 quintals ha^-1 (Table 3).

Actual yield

Actual yield is the final result of the growth and development of corn. This is an important indicator to assess and comment on a plant variety to see whether technical measures are suitable (Imran et al., 2015). Actual yield reflects the real growth and development ability of corn under the influence of genetic factors and external conditions as well as caring regime. High actual yield is the goal of all studies on cultivars and cultivation techniques. Dif- ferent fertilizer rates also led to changes in yield. In other words, that fertilizer rates increased meant the yield also increased. The highest yield was recorded in F₄ at 61.10 quintals ha^-1 and the lowest was in F₅ at 46.40 quintals ha^-1(Table 1). There was a big difference in yield among different fertilizer rates. The figures ranged from 45.53 to 64.51 quintals ha^-1. The actual yield in D₂ was the highest and the one in D₄ was the lowest (Table 2). Different fertilizer rates with different planting density led to different ac-

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QUY TUONG ET AL 1701 tual yield(Mandiæ et al., 2016). Planting density of

D₂ with different fertilizer rates gives the highest actual yield. The yield of the experimental formulas showed a great fluctuation from 40.27 quintals ha^-1 to 73.46 quintals ha^-1, D₂F₄ had the highest actual yield of 73.46 quintals ha^-1 (Table 3). This result is consistent with other published studies that corn yield is affected by planting densities and fertilizer rates (Gökmen et al., 2001; Arif et al., 2010; Imran et al., 2015).

Conclusions

The research results show that corn actual yield has been contributed by cob length, cob diameter, number of grain rows per cob, number of grains per row and 1000-Grain Weight. Planting densities and fertilizer rates have had obvious influences on yield and yield components of NK4300 corn which was grown in northern Vietnam in the winter season.

The cob length, the cob diameter, the number of grain rows per cob, the grain percentage per cob and the 1000-Grain Weight varied considerably as the fertilizer rates and planting density had changed. The number of grains per row was not affected by the planting density or fertilizer rate. It is necessary to use both appropriate planting density and fertilizer rates to achieve high corn yield. The actual yield of experimental formulas varied greatly from 40.27 quintals ha^-1 to 73.46 quintals ha^-1. The formula of D₄ (83 thousand plants ha^-1) combined with F₅(150 kg N + 80 kg P₂O₅ + 60kg K₂O) ha^-1 had the lowest yield. The formula of D₂ (66 thousand plants ha^-1) combined with F₄(180 kg N + 80kg P₂O₅ + 100kg K₂O) ha^-1 had the highest yield at 73.46 quintals ha^-1.

Acknowlegement

The authors would like to thank all participants in this study.

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