Genotype and phenotype diversity of the F2 population three-way cross soybean (Glycine max [L.] Merrill) results

Increasing soybean production through plant crossing helps to supply soybean needs. Three-way crossing of three parents, Grobogan, Anjasmoro, and Dega 1 is expected to increase soybean productivity. Interbreeding is an effort to form a basic population to increase genetic diversity. Based on this, this study aims to determine the diversity of genotypes and phenotypes of the F2 population resulting from a cross between three soybean parents [Glycine max (L.) Merrill]. This research was conducted on Tanjung Selamat Village, Sunggal District, Deli Serdang Regency land. Observations were made by observing all plant populations in the field. Characters observed include plant height, flowering age, number of primary branches, and harvest age. The results showed that the diversity of genotypes and phenotypes of the F2 population varied, this was based on the highest standard deviation value in the F2 population compared to the 3 parent soybean plants. The plant height character has a high diversity value based on the KKG and KKF values.


Introduction
Soybeans are one of the food commodities found in Indonesia.Soybeans are used as food, feed, and industrial materials.The need for soybeans is increasing, so it is necessary to add soybeans through imports [1].BPS reports that the average soybean productivity in Indonesia in 2020 is still 15.69 tonnes and North Sumatra Province is still quite low at under 10 tons [2].
Plant breeding can increase soybean production, one of which is through the process of crossing plants [3] Crossing two parents with superior genetic characteristics aims to produce superior cultivars [4].Plant crossing is carried out to obtain genetic diversity as the formation of a basic population in plant breeding activities [5].High genetic diversity can increase the chances of obtaining new superior varieties [6].
Crossing of soybean varieties has been carried out using the Grobogan x Anjasmoro variety which aims to increase genetic variability with a crossing success rate of 57.14% [7].F1 The results of crossing the variety (Grobogan x Anjasmoro) were backcrossed with the Dega 1 variety where the success rate of the three-way cross ([F1 Grobogan × Anjasmoro] × Dega-1) was 35.37%.Crossing these three soybean varieties is expected to obtain high genetic diversity to produce superior varieties with high yields, large seeds, and early maturity [8].
Research that has been carried out on the F1 generation resulting from crossing three parent soybean varieties (Anjasmoro, Grobogan, and Dega 1) has better scores in the characteristics of seed weight per plant and weight of 100 seeds per plant than the three parents based on heterosis and heterobeltiosis analysis [9].
Based on the description above, the author is interested in researching the diversity of genotypes and phenotypes of the F2 population resulting from a cross between three soybean parents [Glycine max (L.) Merrill].

Research place and time
This research was carried out from February to June 2023 in Tanjung Selamat village, Sunggal District, Deli Serdang Regency, North Sumatra.

Research materials
The materials used in this study included compost, urea fertilizer, KCl fertilizer, TSP fertilizer, sticks of bamboo, fungicides, insecticides, soybean seed varieties such as Grobogan, Anjasmoro, Dega 1, and F2 resulting from crossing Three parents ([Grobogan x Anjasmoro] x Dega 1).A hoe, sickles, waterholes, scissors, analytical balance, sprayer, camera, labels, and stationery were used as tools in this study to conduct observations.

Research methods
This research is a descriptive observation using descriptive statistical analysis.This research used seeds from 3 parent varieties and F2 soybean seeds from a cross between 3 parents [(Grobogan Variety x Anjasmoro Variety) x Dega 1 Variety] and observations were made on each individual in the plant population.The number of plants from the 3 parents was 135 plants with 45 plants for each parent and the number of F2 plants was 450 plants so the total number of plants was 585 plants.Data analysis was carried out by observing the mean, standard deviation, and variety of phenotypes and genotypes.Phenotype Variety (σ2p) is calculated using the formula presented by Suharsono et al (2006), namely Genetic Variation (σ2G) of a population can be calculated using the following formula The Genetic Diversity Coefficient (KKG) and Phenotype Diversity Coefficient (KKF) can be calculated using the formula Based on the KKG and KKF criteria, it is divided into 4 criteria, including low (KKG < 25% or KKF < 0), rather low (KKG < 50% or KKF < 25%), quite high (KKG < 75% and KKF < 50%) and high (KKG < 100% and KKF < 75%) [11].

Research implementation
This study was conducted in the same planting environment by planting and observing each plant F2 and its three parents.Based on the availability of existing seeds, the three parents varieties were each planted with 135 plants and 450 plants of F2.Plots of 120 x 220 cm, and the distance between the plots was 70 cm were used to grow soybean seeds.One seed was placed into each planting hole, which had been dug to a depth of around 2 cm and a spacing of 20 x 40 cm, then inserted one seed per planting hole and then closed again.

Observations parameters
The parameters observed in this research were plant height, flowering age, number of primary branches, and harvest age.Plant height is measured using a ruler from the base of the stem to the last growing point.Flowering age is calculated based on each plant's number of flowering days.The number of primary branches is calculated in the main stem of the number of branches growing.Harvest age is measured based on soybean harvest criteria, and each plant has a different harvest age.

Results and discussion
Table 1 shows the average values and standard deviations of the parent populations of Grobogan, Anjasmoro, Dega 1, and F2 for the characteristics of plant height, flowering age, number of primary branches per plant, and harvest age.The mean value and standard deviation for each character look different from each other and there is an increase in the highest standard deviation value in the F2 population.The F2 population showed different average plant heights, flowering age, number of primary branches, and harvest age, but the average values were close to those of the Grobogan and Dega 1 parent plants (table 1).This shows that the parents of the soybean have the same characteristics as their offspring because the parents of the soybean pass on many genes to their offspring so that the offspring.These characters are included in the maternal effects which are inherited through the genotype of the parents, especially the female parents.Maternal influence is determined by many genes in the nucleus of the female parent's cells so that they can pass on traits and characteristics to the plant [12].
In the characteristics of flowering age and harvest age, it can be seen that the F2 population has a relatively early flowering age and the fastest harvest age compared to its 3 parents.Flowering time and harvest time are related to each other.The faster soybean plants flower, the faster the harvest will be.The results of crossing these three parents are expected to have a fast flowering period and a short harvest period and produce good yield potential [13].
The F2 population showed that the standard deviation value was the highest compared to the 3 plant parents.These results show that diversity in the F2 population is due to segregation that occurs throughout and demonstrated by the genotype frequency distributions.In plants, different segregation patterns are often brought about by the activity and interplay of genes [14].A segregated population is a combination of individuals obtained from a cross and is projected to produce diversity.The initial F2 generation experienced maximum segregation, so genetic diversity was very high and the phenotype was broad [15].
Table 2 shows that the F2 population has different values for genotype variety, phenotype variety, KKG, KKF, and criteria for each observed character.The plant height character shows that it has high criteria in the F2 population based on the KKG and KKF values.Table 2 shows that most of the observed variables have high phenotypic and genotypic diversity values in the characteristics of plant height and flowering age.This shows the high genetic diversity of the F2 population.Plant populations grown under the same conditions will provide different phenotypic and genotypic responses because different genotypes have different nutrient absorption abilities even though they are in relatively the same environment, resulting in differences in phenotypic diversity [16].
In the F2 population, the observed agronomic characteristics largely determine genetic variation.The diversity of the F2 population based on the coefficient of diversity for both phenotype (KKF) and genotype (KKG) on the characteristics of flowering age, number of primary branches per plant, and harvest age is relatively narrow.The diversity is relatively narrow because the diversity of the F2 population is at low and rather low criteria.Plant-height characters have high diversity.High diversity shows that genetic factors play a more important role than environmental factors.Selection characters in the next generation can use by plant height characters (Table 2).
This difference in genotype and phenotype is due to the F2 population experiencing segregation.The extensive level of segregation and recombination in the F2 population can be seen through the distribution of genotype frequencies.The distribution of genotype frequencies can be used as an estimate of inheritance patterns and the number of genes involved in controlling a trait so that these traits can pass on superior traits to their derived plants [17].

Conclusions
The F2 population has an average plant height, flowering age, number of primary branches, and harvest age that is close to the Grobogan and Dega 1 parent plants.The F2 population has the highest standard deviation value compared to its 3 parent plants.Plant height characters have high diversity based on

Table 1 .
Mean values and standard deviations for the parent populations of Grobogan, Anjasmoro, Dega 1, and F2 for the characteristics of plant height, flowering age, number of primary branches per plant, and harvest age.

Table 2 .
Values of genotype variation, phenotype variation, KKG, KKF, and F2 population criteria for the characteristics of plant height, flowering age, number of primary branches per plant, and harvest age.