Yield performance and agronomic characteristics of several candidate hybrid maize varieties on uncultivated land

Corn is currently a strategic and dominant national commodity used as raw material for animal feed. The increase in productivity was made possible by the continued assembly of hybrid corn which has a higher production per hectare with a wide or site-specific adaptation rate. Due to the wide utilization of maize, the main objective of all commercial maize breeding programs is to obtain new inbred and hybrids which will outperform the hybrids mainly on grain yield characteristics. This research was conducted in Bone Regency to know the yield potential of several hybrid maize on uncultivated land, using a randomized block design, 4 replications, a plot area of 3 x 5 m, and spacing of 70 x 20 cm. The material used consisted of 4 hybrids and 2 comparison varieties. The results showed that the hybrid G1603 (11.61 t/ha) showed the highest grain yield and was not significantly different from the comparison varieties. This result was supported by the character of the number of rows of seeds per ear, the length of the ear, and the diameter. These characteristics need to be considered to get hybrid corn with a high grain yield.


Introduction
Corn is the most important food crop in the world after wheat and rice.Corn has been widely cultivated throughout the world because it can adapt to a wide variety of agro-ecological conditions.Corn plants are planted more widely every year and produce more per hectare than other crops [1].The utilization of corn in each country is different, the United States uses most of its corn stock as an ingredient to make ethanol meanwhile, most of the maize stocks in India and Indonesia are used as animal feed.Total world corn consumption in the 2018/2019 period was 1,201,000 tons.The three countries that have the largest total consumption of corn in the world are the United States, China, and the European Union [2].Even though India and Indonesia are not among the top ten countries that have the highest level of corn consumption in the world, corn is one of the main agricultural commodities in these countries [2]Some countries with the highest production levels in the world are the United States, China, Brazil, Argentina, Mexico, India, and Indonesia [3].
In Indonesia, corn is dominantly used as raw material for animal feed.It is estimated that more than 70% of domestic corn is used for feed, and the rest is for the food industry, seeds, and consumption [2].Demand for the domestic market and export opportunities for corn tend to increase from year to year, both to meet the needs of the animal feed industry and the domestically based food industry as well as for exports requiring large quantities of corn products.This situation is a potential market opportunity 1230 (2023) 012129 IOP Publishing doi:10.1088/1755-1315/1230/1/012129 2 for farmers in cultivating corn crops.Thus increasing corn production both in quality and quantity is very important.
The increase in productivity was made possible by the continued assembly of hybrid corn which has a higher production per hectare with a wide or site-specific adaptation rate.Due to the wide utilization of maize, the main objective of all commercial maize breeding programs is to obtain new inbreds and hybrids which will outperform the hybrids mainly on grain yield characteristics [4].The first step in developing varieties is to carry out genotype evaluations.Breeders usually use advanced materials to select superior genotypes or materials to release new varieties [5].Therefore, it is important to know the yield of these genotypes and further the relationship between morphological characters and yields in assembling maize hybrids.This study aimed to determine the diversity of yields and agronomic characters of prospective hybrid varieties on land without tillage.

Materials and methods
This research was conducted in Bone Regency, Bengo sub-district, Liliriawang village, at an altitude of 235 m above sea level, Alluvial soil type, and C2 Oldeman climate type.The genetic material used consisted of 4 candidate hybrid maize varieties namely: G2070, G1603, G1805, and G0888, and 2 control varieties namely PAC339 and P36.This research was conducted using a Randomized Completed Block Design with 4 replications.Tillage was carried out by spraying a systemic herbicide with the active ingredient glyphosate 15 days before planting, then a second spraying with a contact herbicide was carried out 1 week before planting.Planting was done by making planting holes with a hammer in a plot measuring 3 m x 5 m and spacing 70 cm x 20 cm so that the number of each genotype was planted in 4 rows.
Fertilization was done twice with a dose of 300 kg ha -1 Urea and 350 kg ha -1 NPK Poska.The first fertilization is given at the age of 10 days after planting with half the dose of urea fertilizer and the entire dose of NPK fertilizer while the second fertilization is given at the age of 30-45 days after planting with the entire remaining dose of urea fertilizer.Plant maintenance by weeding, irrigation, and pest and disease control is carried out by local cultivation recommendations.The first weeding was carried out by spraying selective herbicides when the plants were 12 days after planting.The second weeding is done at the age of 4 weeks, followed by hill, then the second fertilization.Observations were made on the characters at 50% flowering age (days after planting), plant height and ear height (cm), stem diameter (mm), leaf angle, plant aspect (score), husk covering (score), ear aspect (score), the weight of ear peeled (kg), harvested water content, yield components consisting of diameter and length of ear, number of rows of seeds per ear, the weight of 1000 seeds, shelling percentage, grain yield after converting to tons per ha at 15% moisture content with the formula : Analysis of variance according to the design used and continued with the Lest Significant difference Test (LSD) if there is a significant difference while the score data such as plant aspect, husk covering, and ear aspect were analyzed using Kruskal Wallis with SPSS 23.To determine the relationship between yield components and morphological characters, data were analyzed using the correlation method according to Singh and Chaudhary [6].

Results and discussion
The results of the analysis of variance on the observed characters showed significant differences for male and female flowering ages, plant height and ear height, leaf blight attack score, husk covering, plant aspect, ear aspect, shelling percentage, moisture content, grain yield, number of seed rows per ear, ear length, ear diameter, and leaf angle while leaf rust score, 1000 seed weight, and stem diameter showed no significant differences (table 1).Significantly different characters need further testing to find out which genotype contributes to the observed differences [7].Significant differences for all observed characters indicate that the genotypes tested showed a variety of appearances.The appearance of plants in a growing environment is the result of interactions between genetic and environmental factors.Therefore, the response of a plant genotype to the environment is different in different environments, or the response of plants is different to the same environmental conditions [8].The corn plants tested had different day 50% silking and day 50% anthesis and were statistically significantly different (table 2).Hybrid G1805 produced male and female flowers the fastest, while hybrids G0888 and G1603 produced male flowers and female flowers the longest.Hybrid G1603 had male flowers for 55 days, and female flowers for 54 days (table 2).The female flowering age ranges from 52-55 days while the male flowering age ranges from 52-54 days.The age of male and female flowering can be used as a benchmark for the age of harvest of plants and the average vulnerability of male and female flowering is only 1 day.Corn plants that are widely developed have a few leaves around 20-21, the age of female flowering is about 65 days after planting, and the age of maturity is around 100-125 days after planting [4].The flowering age is important in determining the harvest period of corn plants and early maturing maize varieties are always desired, especially in multiple cropping systems [9] Plant height showed a significant difference (table 2) with the highest hybrid being G1603 (231.57cm) and the lowest hybrid being G2070 (216.62 cm) which were statistically significantly different from the comparison varieties P36 and PAC399.The cob height of the tested hybrids was not significantly different, but the 4 tested hybrids were significantly different from the comparisons P36 and PAC399 (table 2).The maximum ear height was shown by hybrid G1805 (112.22 cm) and the minimum ear height was shown by hybrid G1603 (107.95 cm) and was statistically significantly different from the control varieties.Plant height and ear height characters play an important role in plant resistance to lodging.Therefore, these two characters always receive attention from breeders when establishing new populations that are tolerant of lodging.The desired plants are short plants with cobs positioned in the mid-height of the plant because the plants are usually resistant to lodging and better distribution of photosynthetic results which contribute a lot to grain yields [10].Ear height indirectly increases yield by reducing fallen plants [9].
Observations on leaf blight were still classified as resistant with an average score of 1.29.The highest attack was found in the PAC399 control variety with a score of 2 and statistically significantly different from the other candidate varieties tested (table 2).Leaf rust disease was also observed to be resistant with an average score of 1.38.The attack of rust disease was not statistically significantly different between the hybrids tested and the control varieties (table 2).To anticipate the rapid adaptation of pathogens, it is important to develop new varieties that are resistant to blight and leaf rust [11].According to Muis et al. [8], in corn plants that are attacked by leaf blight, leaf rust disease is usually also found, and vice versa.The husk cover was good with an average score of 2.10, only hybrid G0888 (2.50) was different from the comparison varieties and other test hybrids.The plant aspect is also quite good with an average score of 2.04.The best plant aspect was shown by hybrid G1603 (1.50) and did not differ from the two control varieties.The ear aspect is good with an average ear score of 1.54.The hybrids G1805 and G2070 showed good ears with respective scores of 1.50 (table 3).
The shelling percentage of the hybrids tested showed significant differences (table 3).The highest shelling percentage was found in hybrid G1805 (0.83%) but it was not different from hybrids G0888 and variety P 36 respectively (0.81%).Shelling percentage in corn commodity is the ratio between the net weight of the corn kernels and the weight of the corn kernels which are still together with the cobs.The water content at harvest of the test hybrids ranged from 31.07-34.88%.Statistically, hybrid G1805 (31.73%) showed no significant difference in water content from variety P36 (table 3).
The average stem diameter is 18.09 mm.Hybrid G1603 showed a large stem diameter (18.89 mm) while hybrid G1805 showed a small stem diameter (17.71 mm).The character of stem diameter is closely related to resistance to lodging.Large stem diameter is more resistant to felling.
Leaf angles were significantly different, and the 3 hybrids tested (G1603, G1805, and G2070) exhibited leaf angles that were greater than both controls and the average values.One hybrid (G0888) had small leaf angles, smaller than the average of both control varieties.Small leaf angles indicate more upright leaves, and more efficient use of sunlight, and can be planted with dense populations so that the number of plant populations is optimum.The weight of 1000 seeds did not show a significant difference (table 4).Hybrid G1603 (343.01 g) was the highest but not significantly different from all the hybrids tested.The lowest 1000 seed weight of the tested line was G2070 (301.09g).The character of the weight of 1000 seeds and the length of the ear are the main factors contributing to the main yield and are crucial factors for selection [12] The number of seed rows showed a significant difference (table 4).Hybrid G1805 had the highest number of rows and did not differ from the comparison varieties P36 and PAC399.The range of the number of seed rows per ear of the hybrids tested was 13.35-15.20.Most of the hybrids tested had as many as 14 rows of seeds [11] showing that the number of rows of seeds per ear and grain yield showed significant differences for these two traits among the populations tested.The number of grain rows per cob is an important yield parameter and contributes to the total grain production [12] Ear length showed a significant difference (table 4).Hybrid G1603 showed a longer cob (19.11 cm) among the 4 hybrids tested and was different from P36 while hybrid G1805 showed a shorter ear (16.95) but was not different from the PAC399 variety.According to Ur Rehman and Kahan [12] the net grain yield of corn plants is influenced by the character of ear length and the results of their research show that the average range of ear length is 17.28-22.47cm.Observation of ear diameter showed a significant difference (table 4).The largest ear diameter was shown by the PC399 variety (50.88 mm) and did not differ from the G1805 hybrid (49.43 mm).
The grain yield was not significantly different, ranging from 10.22 to 11.61 t/ha.The test hybrid that showed the highest yield was G1603 (11.61 t/ha) and did not differ from all the controls.This high yield is supported by better agronomic characteristics such as plant height, ear height, plant and ear appearance, and husk covering, as well as better yield components such as ear diameter, ear length, and the number of row seeds per ear.Grain yield is a complex trait, influenced by several other characteristics so the direct selection of grain yield is usually ineffective [13].

Correlation coefficient
Correlation analysis studies and path coefficients need to be carried out to better understand the relationship between yield and yield-related characters [13].Components that affect a trait both positively and negatively are determined through correlation estimation [14].The correlation of several characters with seed yield is presented in (table 5).In this study, the characters of the number of rows of seeds per ear, ear length, and ear diameter showed a real and positive correlation to grain yield.It means that these characters are very decisive in improving yield and these three characters are the most important yield characters. Selection of these three characters will most likely result in an increase in the yield capability of the maize population [1] and these characters can be considered for indirect selection to increase grain yield.[15].The significant positive correlation between the two characters indicates that the characters can be improved simultaneously in the selection program due to the strong relationship between the two characters [15].Muliadi et al., [16] reported a positive and significant correlation between grain yield and the number of seed rows per ear, ear length, and ear diameter.The results of the study by Izzam et al [9] also reported that ear length contributed directly to the grain yield.The number of seed rows per ear with grain yield is an important parameter for grain yield and total grain production [17].Research by Aliu et al. [18], Soumya et al [19] and Yahaya et al [20] found that ear diameter showed a significant correlation to grain yield.Genotypes that have the number of seed rows per ear, large ear diameters, and long ears will give higher grain yields.Grain yield is a complex trait, influenced by several other characteristics so the direct selection of grain yield is usually ineffective [14] and [21].
A negative and significant correlation was shown by grain yield with husk cover (r= -0.50) and ear aspect (r= -0.56) (table 5).This means that plants that show poor husk cover and ear aspects will also give bad results because the ears are not tightly closed so they are easily attacked by pests, especially ear borers, and during the rainy season, the ends of the ears will rot, and seeds can grow.This situation will affect the ears' appearance, ultimately affecting the grain yield.The results of Tulu (2014) [1] on Quality Protein Maize showed the same results, namely grain yield had a significantly negative correlation with husk cover and ear aspect.

Conclusion
There was 1 hybrid that showed a higher grain yield than the control variety, namely G1603 (11.61 ton ha -1 ).This hybrid needs to be tested in several locations to be proposed as a candidate for a new hybrid corn variety.The results obtained were supported by good agronomic characteristics and yield components such as the number of rows of seeds per ear, ear length, and ear diameter.These characters can be considered for indirect selection to increase grain yield.

Table 1 .
The mean square of yield characters and yield components of several new varieties of hybrid corn

Table 2 .
Average of the agronomic character of several candidate New Varieties of hybrid corn in Bone Means followed by the same letter in the same column have no significant difference.

Table 3 .
Average several agronomic components of candidate new varieties of hybrid corn in Bone Husk cover; PA: Plant aspect; EA: ear aspect; SP: Shelling percentage MC: Moisture content; SD: Stem diameter; LA: Leaf angle; Means followed by the same letter in the same column have no significant difference.

Table 4 .
Average yield and yield components of several candidate new varieties of hybrid corn in Bone Weight of 1000 seeds; NSR: Number of seed rows per ear; EL: Ear length; ED: Ear diameter; Y: Grain yield; Means followed by the same letter in the same column have no significant difference.