Soybean types
There are a number of factors that have to be considered when selecting a variety of soybean that will have the genetic potential to produce a good crop in accordance with the local conditions.
The characteristics that have to be considered include yield and yield stability, resistance to pests and diseases, iron deficiency chlorosis, maturity, quality traits, plant height and lodging.
Height and lodging
Taller plants are in general more susceptible to lodging than lower varieties. Lodging reduces yield and complicates harvest.
Maturity Group
Maturity is classified according to the time needed from flowering to harvest maturity. If soybeans from different maturity groups are planted, there can be a reduced risk for drought damage by spreading out flowering, seed fill and physiological maturity. But the local conditions must be taken into consideration, as soybean reacts to daylength. Growing a variety at higher latitudes than what is normal for the specific variety, the longer days will induce flowering at a later stage, thus extending the time needed to mature. A variety from higher latitudes moved closer to the equator, will flower earlier than it should in its ideal geography. Flowering prior to the plant’s adequate height may reduce yields.
Grain Composition
Higher contents of oil, protein and amino acids are important for assessing the value of a soybean crop.
Disease Tolerance
Genetic disease tolerance is another major consideration. This is particularly important for difficult diseases such as Sudden death syndrome and White mold. On soils with high pH, some varieties can be susceptible to Iron deficiency chlorosis, while others are more tolerant.
Other Aspects
In tropical and sub-tropical countries, there has been an increased demand for cultivars with shorter cycles, which allow a winter crop (especially in regions with two maize crops) with lower risks and higher earnings. However those cultivars have presented problems such as lower production potential, low height and increased susceptibility to drought. Currently, these challenges are being overcome with the launch of new materials each new year, adding a higher yield potential, better size and increased resistance to drought besides of precocity. Another important aspect is the higher availability of soybeans with resistance to caterpillar attack. It is a second generation of genetically modified soybeans, in the wake of already established RR soybean (resistant to glyphosate), which has changed the course of the crop in the last decade.
