Research Article
Yield Potential of Sweet Corn as Influenced by Different Levels of Nitrogen and Plant Population
Not Available
Miftahullah
Not Available
Muhammad Tariq Jan
Not Available
Amanullah Jan
Not Available
Ihsanullah
Not Available
Sweet corn (Zea mays sp. saccharata) belongs to the family Poaceae. It has wrinkled seeds and like other types of corn it is used as livestock feed, as human food and as raw material in industry. For increasing human population have to exploit the entire food crops to meet the increasing demand. Among the yield increasing factors, plant population and balanced N fertilization is of primary importance because in case of thick plant population most plants remain barren and grain size also remains small and lodging also takes place. Similarly, if the nitrogen requirements are not fulfilled properly, the lower leaves begin to turn pale and if the deficiency persists, cob size will remain small, the grains are shrinked and vegetative growth will adversely affected.
Park et al. (1989) reported that increasing plant density from 40000 plants ha-1 to 111110 plants ha-1 increase plant height and then starts declining because of more tense competition. Peter et al. (1989) who observed that 1000-grains weight decreased with increase in plant population and increase with increase in nitrogen levels. Novero et al. (1992) in a field trial on different levels of nitrogen (0, 75, 150, 225 and 300 kg N ha-1) at maize cultivars, reported highest biological yield (15767 kg ha-1) for 225 kg N ha-1. Masheswarappa et al. (1994) reported that number of cobs/plant, 100-grains weight and plant at harvest decreased with increased plant population and further reported that grain yield was the highest (5000 kg ha-1) at 165 kg N ha-1 with 125000 plants ha-1. Stone et al. (1998) reported that yield and quality of super sweetcorn cv. Challenger are sensitive to changes in plant density and nitrogen nutrition.
This study examined the effects of plant population (nine populations ranging from about 30, 000 to 140, 000 plants ha-1) and nitrogen (N) fertilizer (0 or 250 kg N ha-1) on yield and quality. When N fertilizer was added, ear and grain yield increased with increase of plant population, throughout the population range examined. When N was limiting ear and grain yield increased with population up to around 90 000 plants/ha, then remained unchanged. Turgut (2000) reported that increased plant population and nitrogen level delayed days to tasseling, days to silking and days to maturity and increased seed number per ear, fresh ear weight and number of ears per plant.
The research work was conducted on a wide range of plant population and nitrogen levels to determine optimum plant population of the crop and to determine optimum dose of nitrogen, also to determine best interaction of plant population and nitrogen level.
A trial was conducted at Malakandher Research Farm, NWFP Agricultural University, Peshawar during 1998-99 to study the effect of various plant populations (60000, 90000, 120000, 150000 and 180000 ha-1), nitrogen levels (0, 100, 150, 200 kg N ha-1) and their interaction on the performance of sweet corn. The experiment was laid out in randomized complete block design with split plot arrangement, allotting plant population to main plots and nitrogen levels to sub plots. Net sub plot area was 12 m2. The desired plant population was maintained by removing extra plants from each row. In 60000 plants ha-1, plant-to-plant distance was 33cm. In 90000-plant ha-1, plant-to-plant distance was 22 cm. In 120000 plants ha-1, plant-to-plant distance was 16 cm. In 150000 plants ha-1, plant-to-plant distance was 13 cm. In 180000-plants ha-1, plant-to-plant distance was 11 cm. Data was recorded on days to tasseling, days to silking, plant height (cm), days to maturity, number of plants ha-1 at harvest, number of ears/plant, biological yield (kg ha-1), grain yield (kg ha-1), 1000 grains weight (g).
Data was statistically analyzed according to RCBD split plot arrangement, the analysis of variance and LSD was used according to Steel and Torrie (1980).
Tasseling (Table 1) was delayed with increasing planting density. Maximum days (55.43) to reach tasseling were recorded for planting density of 180000 plants ha-1 (Turgut, 2000) Maximum days (57.35) were taken by the plants that received 200 kg N ha-1, while minimum number of 50.95 days was taken by control that received no nitrogen. Plant population and nitrogen levels not significantly interacted regarding days to tasseling.
Plants thinned to 180000 plants ha-1 took maximum number of 68.43 days to silking (Table 2). Silking delays linearly with increase dose of nitrogen. Plants that were given 200 kg N ha-1 took maximum number of 69.50 days to silking, while plants received no nitrogen took minimum days (63.45 days) to silking. Plant population and nitrogen levels not significantly interacted regarding days to silking.
Tallest plants (Table 3) of 135.76 cm were observed in plots that were thinned to 180000 plants ha-1. These results are not in conformity with Park et al. (1989). Plant height increased linearly with the increase in nitrogen and tallest plant height (140.23 cm) was observed in plots that received 200 kg N ha-1 and plots that received no nitrogen resulted in the smallest plant height of 123.96 cm (Chabra and Sing, 1986). Plant population of 180000 ha-1 interacting with N level of 200 Kg ha-1 took produced highest plant height (141.87 cm).
Maximum days to maturity (100.35 days) were taken by plants that were thinned to 180000 plants ha-1, (Table 4) plants population of 60000 plants ha-1 took minimum number of 92.45 days to maturity (Turgut, 2000). Maturity of the maize crop was delayed by increased supply of nitrogen and maximum days to maturity (102.70 days) were taken by plants at 200 kg N ha-1, while plants that received no nitrogen took 94.2 days to maturity.
Table 1: | Days to tasseling of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 1.692 and nitrogen level = 0.7821 |
Table 2: | Days to silking of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 1.401 and nitrogen level = 0.8724 |
Table 3: | Plant height (cm) of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 2.759 and nitrogen level = 1.352, interaction = 3.024 |
Table 4: | Days to maturity of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 0.7979, nitrogen level = 0.4821 and interaction =1.078 |
Table 5: | Number of plants at harvest ha-1 of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 1094.0, nitrogen level = 701.6 and interaction = 156.9 |
Plant population of 180000 ha-1 interacting with 150 Kg N ha-1 took maximum days to maturity (103.8)
Number of plants ha-1 at harvest (Table 5) was to know the effect of planting densities on mortality rate. A plant population on number of plants ha-1 at harvest showed that mortality of plants ha-1 was high (28211 plants ha-1, Table 5a) for maximum plant population of 180000 plants ha-1.
Table 5a: | Number of plants ha-1 lost at harvest of sweet corn as affected by different levels of nitrogen and plant population |
Table 6: | Number of ears plant-1 of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 0.1168, nitrogen level = 0.08304 and interaction = 0.1857 |
Table 7: | Biological yield (kg ha-1) of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 322.0, nitrogen level = 217.2 and interaction = 485.6 |
Table 8: | Grain yield (kg ha-1) of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 76.11, nitrogen level = 56.64 and interaction = 126.6 |
Table 9: | 1000-grains weight of sweet corn as affected by different levels of nitrogen and plant population |
LSD value for plant population = 2.467, nitrogen level = 5.400 and interaction = 5.516 Means followed by different letters are significantly different at P< 0.05 |
Maximum number of plants (104182 ha-1) was harvested for N level of 150 kg N ha-1 while minimum number of plants (102508 ha-1) was harvested for control plots. Interaction of the two factor was non significant.
Maximum number of 1.61 ears/plant (Table 6) was obtained from low population density of 60000 plant ha-1. Number of ear/plant increased in a linear fashion up to 150 kg N ha-1 and then started reduction. Maximum ear/plant (1.45) were taken by plots that received 150 kg N ha-1. Population density of 60000 ha-1 interacting with 150 Kg N ha-1 produced maximum of 2.10 ears/plant (Maheswarappa et al., 1994).
Results deducted from various planting densities showed that biological yield (Table 7) increased with increasing planting densities. Maximum biological yield (11890.90 kg ha-1) was recorded in plants population of 180000 plants ha-1 while minimum biological yield (10078 kg ha-1) was recorded in plots with 60000 population of plants ha-1. Highest biological yield (12291.1 kg ha-1) was recorded for 200 kg N ha-1 while minimum 9777 kg ha-1 of biological yield was recorded in control plots. Maximum biological yield (12689.2 kg ha-1) was recorded for plant population interacting with 200 kg N ha-1 (Novero et al., 1992).
The response of grain yield to planting density (Table 8) was such that lower grain yield of 1498.3 kg ha-1 was obtained from lower plant density of 60000 plants ha-1 as well as dense population of 180000 plants ha-1 also gave lower grain yield of 1559.50 kg ha-1. Grain yield increased up to medium plant density but decreased with further increase in planting density. Maximum grain yield of 1777.42 kg ha-1 was obtained at planting density of 120000 plants ha-1. Nitrogen level of 150 kg N ha-1 resulted in the greatest grain yield (2006.95 kg ha-1); grain yield reduced to 1983.95 kg ha-1 by increasing nitrogen from 150 to 200 kg ha-1. Maximum grain yield ha-1 (2195.75) was for plant population of 120000 ha-1 interacting with nitrogen level of 150 kg ha-1(Novero et al., 1992; Stone et al., 1998).
The result (Table 9) revealed that 1000-grains weight reduced with increase in plant population. Population of 60000 plants ha-1 gave heavier 1000-grains weight (125.97 g), while plants population of 180000 plants ha-1 gave lighter 1000-grain weight (118.83 g). Nitrogen level of 150 kg N ha-1 gave heavier 1000-grains weight of 132.73 g, while plants received no nitrogen gave lighter grain weight (108.29 g). Maximum 1000-grains weight (135.67 g) was recorded for plant population of 60000 ha-1 interacting with 150 Kg N ha-1 (Peter et al., 1989). Summing up 120,000 plants population ha-1 interaction with 150 kg N ha-1 gave the maximum grain yield of 2195.75 kg ha-1.