The adaptability of soybean high yield varieties and farmer preferences in dry land area

Soybean development is currently directed to dry land areas. To support this program, IAARD has released some new varieties with a yield potential above 3 tons/ha. The aim of this study was to know the adaptability of new varieties of soybean and farmers preference in dry land areas. The field experiment was conducted in Grobogan Regency, using factorial randomized block design with two factors. The first factor was fertilizer dosage combined with bio fertilizer and the second factor was five soybean varieties. Farmer preference test was performed by interviewing the respondents. Measurements of the farmer attitudes, opinions, and perceptions was done using Likert scale. The results showed that Grobogan variety was better adapted to the dry land conditions of Grobogan Regency. The application of fertilizers combined with biofertilizers increased soybean growth and production. The highest plant (52.42 cm) and the highest soybean yield (2.165 t/ha) were obtained in the farmer’s dosage treatment combined with biofertilizers. The order of farmers preference for the tested varieties was Grobogan, Biosoy, Devon, Dega and Detap. These preferences were mostly based on crop productivity, seed size, seed availability, and ease of selling the yield.


Introduction
Soybean is a national strategic food commodity.The need for national soybean consumption continues to increase with the population increase, per capita income, and public awareness of food nutrition.In Asian countries, including Indonesia, soybeans are used primarily as food and animal feed.Krisnawati [1] suggests that two-thirds of soybean needs are used for food consumption, while the remaining are used for edible oil production.
In line with the growth of Indonesia's population, the need for soybean consumption continues to increase every year.In 2015, soybean consumption reached 2.54 million tons of dry beans, consisting of direct consumption of the population 2.3 million tons, the remainder for other needs, such as nonfood and dairy industries [2].In 2019, the national soybean production was 480 thousand tons, which was only 16.4% of the national production target, while soybean imports reached 2.67 million tons [3].This condition is due to the low soybean productivity.
The main challenges faced in soybean production in Indonesia are planting/harvesting area and soybean productivity.During the last five years soybean productivity has ranged from 1.35-1.55tons/ha.In 2019 the government has announced a national soybean production of 2.8 million tons which requires planting area of 2.24 million hectares, while the available planting/harvesting area during 2014-2018 ranges from 576 -680 thousand hectares.In addition to paddy fields which covers 8.1 million hectares, other types of land targeted to expand soybean planting area are sub-optimal land, including dry land To address the low soybean productivity, IAARD has released new high yielding varieties with potential yields above 3 tons/ha and large seed sizes [4], including Dega 1, Detap 2, Grobogan and Biosoy varieties, with potential yield of 3.5; 3.58; 3.4 and 3.5 tons/ha, respectively.It is well known that tempe producers prefer large-sized soybeans, hence the introduction of the above varieties is expected to meet the needs of tempe producers.
Soybean development is currently focused to dry land areas because the potential for dry land is still quite wide.According to land resources study, around 5.3 million hectares of dry land were very potential and very suitable for soybean development [5], which is mainly spread in the provinces of East Java, Central Java, West Sumatera, West Papua, West Java and South Sulawesi.The use of dry land for soybean development is in line with the four targets of the Ministry of Agriculture, one of them is the expansion of food production to sub-optimal land, including dry land with dry climate.The majority of farmers in this area prefer to cultivate corn as a source of income.In terms of soil fertility, the soil is generally relatively fertile.
This study aims to investigate the adaptability of some high yield varieties of soybean and farmers preference in dry land areas

Research methodology
This research consists of two activities, first activity was a field experiment to test the adaptability of five varieties to dry land condition, and the second was a survey to determine the farmer's preference on soybean.

Field experiment
The field experiment was conducted in Nambuhan Village, Purwodadi District, Grobogan Regency, using a factorial randomized block design with two factors.The first factor was fertilizer dosage with four treatments of fertilizers dosage (as shown in Table 1), and the second factor was soybean varieties.Five varieties were tested in this experiment, i.e., Grobogan, Biosoy, Dega, Detap and Devon.These varieties have significantly different characteristics.The biofertilizer used in this experiment contain Methylobacterium sp. which is known as a bacterium that reveals phytohormone [6].

Preference test
The primary data was collected from the soybean farmers who have planted the seeds of the soybean varieties studied.The number of respondents were 30 people.Attributes in this preference study include productivity, resistance to pests and diseases, plant age, germination rate, seed size, seed color, ease of obtaining seeds and selling the yields, and the crop appearance in the field.Each attribute has parameter 3 -12 statements.Measurements of the farmer attitudes, opinions, and perceptions was done using Likert scale [7].The Likert scale uses five levels of answers, where the values are 5 (strongly agree), 4 (agree), 3 (neutral), 2 (disagree), and 1 (strongly disagree).Level of farmer preference was determined using the following equation: T x Pn, where T is number of respondents and Pn is Likert score.

Soil and climatic conditions
Based on the map of soil distribution in Grobogan Regency, the type of soil commonly found in Purwodadi District is Alluvial soil which is indicated by brown color, where in some areas many silt deposits are found containing sand and clay.The physical properties of Alluvial soil are solid and amorphous structure and slow permeability.The chemical properties of Alluvial soils are constrained by the availability of nutrients, low soil pH, high Al solubility, while the biological properties of alluvial soils are constrained by poor microorganism activity.
The soil of the experiment site is classified as acidic with low organic C content (1.3%).The N, P and K content is low, which is a characteristic of alluvial soils.Base saturation was high (64%) with moderate to high levels of Ca and Mg (Table 2).Based on this result, soil fertility in the experimental site was classified low.The type of climate at the research site was classified as type C (Oldemann) with 6 dry months (rainfall <100 mm/month) and 5-6 wet months (rainfall > 200 mm/month).The dry month occur between April -September, while the rainy season occurred during October to March.Farmers in this area usually plant soybean between April to June, when soil moisture is sufficient for the optimal soybean growth.This is in line with the calculation by Kinasih et al. [8], where 3-4 months after the rainy season the condition of groundwater is surplus, and it can be used to grow soybeans.The same thing was stated by Mustikawati et al. [9].Soybean water requirement correspond to the growth stage, where at the early of growth it needs a little water, and reaches its peak in the flowering and pod filling phases, then decreases in the maturity phase until harvest.Wijewardana et al. [10] stated that optimal soil moisture conditions resulted in plant height growth, productive branches and the highest number of pods.

Crop growth and yield
Table 3 shows that statistically there was no significant combination effect between the two tested factors in this experiment, however each factor separately affected crop growth and yield, significantly.3 shows that not all varieties tested were able to adapt to dry areas.Based on the plant height, two varieties, namely Grobogan and Biosoy, were able to adapt to dry land.These two varieties were able to grow consistently with the variety description, while the other three varieties were lower than the average plant height as stated in the variety description.The ability to adapt to the environment is a characteristic of each variety [11,12].Soybean crops adapted to drought by reducing the leaves number, the leaf area, or by folding leaves.This crop mechanism affects crop growth, seed yield, water use efficiency, and radiation use efficiency [13].
Dega and Biosoy varieties produced smaller soybean seeds, which was only 81.33% and 93.97% respectively, compared to the seed size potential varieties.In contrast to Grobogan, Detap and Devon varieties, they were able to produce even larger soybean seed sizes compared to the seed size potential varieties.
The results show that Grobogan variety was better able to adapt to dry areas.This is because Grobogan has long been developed in the dry area.Grobogan variety produced the highest yield (2.4 tons/ha), however, it still falls below its yield potential of the variety.Compared to the yield potential (3.4 tons/ha), the production obtained from this study only reached 70.65%.Meanwhile the yields for the Devon, Detap, Dega and Biosoy varieties were only 48.41%, 53.43%, 51.53% and 69.51%, respectively, compared to the variety yield potential.The high crop yield was associated with a combination of genotypes, water availability during the vegetative cycle and early flowering stages as well as, and during reproductive phases [12].
Fertilizer treatment combined with biological fertilizers had an effect on soybean growth and yield of soybean (Table 3), especially on productive branches, number of pods, weight of 100 seeds and soybean yield.The application of recommended fertilizers and biological fertilizers produced the highest plants (52.42 cm) but not significantly different from the doses of farmer's fertilizers (48.27 cm).The effect of this treatment may be related to the addition of biological fertilizers containing Methylobacterium sp.Methylobacterium sp is known as a bacterium that able to grow in a N 2 free medium, produce indole acetic acid and solubilizes mineral phosphate [14][15][16].Therefor the addition of biofertilizer was able to improve the growth and yield of soybeans.
Senthilkumara et al. [16] found that the use of Methylobacterium sp. in rice was able to increase the growth of the lateral roots of rice, thereby increasing the growth and yield of rice.Rahim et al [15] suggested that Methylobacterium sp bacteria are able to increase dissolved phosphate which is very much needed by plant growth.In this study the fertilization packages were always supplemented with organic fertilizers because all studies indicated the need to use organic fertilizers [17][18][19].
The application of biofertilizer containing Methylobacterium sp did not affect number of nitrogen fixing bacteria in the soil.This finding was not in line with the statement Grossi et al. [14], however, it was similar to the research result of Rahim et al. [15] which is found that Methylobacterium sp was found poorly grew on two nitrogen-free media.Figure 2 presents the logarithms of the number of nitrogen-fixing bacteria, varied between 1.78 x 10 6 and 6.75 x 10 7 CFU/g soil.

Farmer's preference
To determine farmers' preferences for introduced soybean varieties, interviews were conducted with participating and non-participating farmers.There are nine parameters asked to the farmers, namely the superiority of the varieties, productivity, resistance to pests and diseases, harvesting age, color, shape and size of seeds, the availability of certified seeds, ease to sell and crop performance.From the data analysis, there are four aspects that are considered by the farmers in choosing varieties, namely crop productivity, size of seeds, the availability of certified seed, and ease to sell.
The order of farmer preference to the introduced varieties are Grobogan, Biosoy, Devon, Dega and Detap (Table 4).This choice mostly based on the crop productivity, seed size, the availability of certified seeds and ease of yield selling.Compared to other varieties, Grobogan resulted the highest yield (2.4 t/ha) followed by Biosoy (2.282 t/ha).Seed size is an important factor for farmers in choosing varieties because it determines the ease of selling the product.Tempe producers prefer large seeds for making tempe [20], even though, there is no correlation between soybean seed size and the quality of tempe [21].Another factor that determines farmer preference is the availability of seeds in the field.Farmers will plant varieties that are more readily available.Yofa et al [22] stated that in order to increase the acceptance and use of high-yielding soybean varieties, the availability of these highyielding varieties must be guaranteed.According to Prasetiaswati et al. [23], the resistance of varieties to drought is an important factor that is considered by farmers in choosing varieties.

Grobogan variety
Grobogan variety has long been developed in Grobogan Regency.Ripe pods do not break easily, and at harvest the leaves drop 95-100%.The color of the seed coat is light yellow, the ripening age is about 76 days, the plant height is 50 -60 cm, and the weight of 100 seeds is approximately 18 g.This variety is able to adapt well to several growing environmental conditions [24].
The yield of Grobogan variety is quite varied, depends on the crop management applied by the farmer.The Grobogan variety is resistant to several pests and diseases, such as bean seed fly, shoot fly, snake pod moth, leaf rust, sprout damping and mosaic virus from 12 types of pests and diseases [25].According to the farmers, the price of the seeds of the Grobogan variety is quite expensive, but the stock seeds (SS) are easy to obtain, and the selling price is quite high.Biosoy variety has a yield potential of 3.5 tons/ha, however the actual yield at the farmer field ranged between 1 -2 tons/ha.This variety resistant to pests and diseases of red mites, leaf roller caterpillars, leaf rust, sprout damping and mosaic virus.According to the farmers, the seed price of this variety is expensive, but the seeds are easy to obtain, the selling price is lower than Grobogan.

Devon variety
The Devon variety has high isoflavone content ( 2,200 µg/g) which acts as an antioxidant.Therefore, this variety could be used as a functional food source.The yield potential of Devon is 3.09 t/ha, 83 days of harvest, large seeds (15.3 g/100 seeds), and 35% protein content [25].Farmer prefer to plant this variety; however, their preference is still below the Grobogan and Biosoy varieties, only 69.23% of the respondent choose to plant Devon.Harvest age of Devon variety is 86 -90 days and the germination/growth rate is 80-90 percent.This variety has a small seed size <10g/100 seeds.The seeds price is quite expensive and a bit difficult to obtain, the selling price of the produce is lower than that of Grobogan and Biosoy.

Dega variety
Yield potential of this variety is 3.82 t/ha.ripening age of 71 days, large seed size (22.98 g/100 seeds), and early maturity [25].Dega 1 is the favorite soybean because it is classified as a soybean with large and early maturing seeds.The Dega variety is quite resistant to pests and diseases of red mites, shoot flies and leaf roller caterpillars.Resistant to bean seed fly, leaf rust, sprout damping and mosaic virus.The seeds price of Dega variety is quite expensive and difficult to obtain, the selling price of the product is lower than that of Grobogan and Biosoy.

Detap variety
The advantages of the Detap variety are resistant to lodging, resistance to pod breaked, large seed size (15.37 g/100 seeds), yield potential 3.58 t/ha, protein content of approximately 40.11% dry weight, and fat content of approximately 16.16% dry weight.This variety is resistant to leaf rust disease, sensitive to SMV virus disease, resistant to pod-sucking pests, moderately resistant to pod borer pests, and sensitive to armyworm pests [25].The farmer prefer to plant Detap since it has large seeds, early maturing, resistant to pod splitting and has high productivity and can reach up to 2.9 t/ha.However, in this study, the productivity of the Detap variety was only 1.74 t/ha.

Conclusion
From this study, it can be concluded that each variety has different capability to adapt to the dry areas, where Grobogan variety was found better adapted than other introduced varieties.The addition of biological fertilizers to fertilization increased the growth and yield of soybean plants by 10.85 -18.93%.The order of farmer preference to the introduced varieties are Grobogan, Biosoy, Devon, Dega and Detap.This choice mostly based on the crop productivity, seed size, the availability of certified seeds and ease of yield selling.

Figure 1 .
Figure 1.The distribution of rainfall and rainy days on the research site.

Figure 2 .
Figure 2. Number of nitrogen fixing bacteria (log CFU/g soil) under different fertilization dosage and soybean variety.

Table 1 .
Experimental treatment of the study.

Table 2 .
Physical and chemical properties of soil in the experimental site.

Table 3 .
Growth and yield of five soybean varieties and under different fertilizer treatment.

Table 4 .
Farmer's preference of the introduced varieties