How Do Cultural Practices Affect Soybean Growth And Development

2.1.3 Cultural Practices Affecting Soybean Growth and Development
The choice of cultivar plays a great role in increasing soybean production. Soybean genotypes are sensitive to changes in environmental conditions where the crop is grown. Therefore, it is necessary to study the interaction between genotype and environment in order to identify the genotypes that are stable in specific environments (Calvino et al., 2003). This has resulted in the classification of soybean into thirteen (000, 00, 0, I, II, III, IV, V, VI, VII, VIII, IX and X) different maturity groups (Mundstock 2005). In the United States of America (USA), soybean maturity groups range from 000 in the extreme north to VIII in the southern Gulf Coast area and Florida. Usually
Research has shown that soybean nodulation and yield can be affected by the interaction of nitrogen and phosphorus in the soil (Singh et al., 1994; Sanginga et al., 1996) thus making these essential for exploiting maximum yield potential of the crop (Harper et al., 1989). According to Kumaga and Ofori, (2004) phosphorus and inoculation significantly affect soybean nodulation, growth, and yield parameters. Phosphorus plays a key role in the energy metabolism of all plant cells, particularly in nitrogen fixation as an energy-requiring process. Nodules are strong sinks for phosphorus, which reaches concentrations three fold higher than in other organs (Kumaga and Ofori, 2004). Moreover, soil deficiency in phosphorus limit the extent of nodulation, nitrogen fixation, and seed yield of legume crops (Akpalu et al. 2014). Phosphorus, apart from its effect on nodulation process and plant growth, exerts some direct effects on soil rhizobia (Singleton et al., 1992). Phosphorus is the most critical nutrient limiting soybean production, and is deficient in the majority of soybean-cultivated areas (Nandini, 2012). Research indicates that, soybean yield positively responded to phosphorus fertilization in the Nigeria savannahs (Kamara et al., 2007). Nandini (2012) reported maximum grain yield and total phosphorus uptake in soybean using single super phosphate (SSP) plus phosphorus solubilising bacteria (PSB). According to him, yield attributing characters, grain and stover yield increased with increasing levels of phosphorus. The response of soybean to phosphorus fertilization depends on soil moisture status and pH. Soil moisture stress and acidity may decrease the release of phosphorus in the soil, which may result in poor biomass production and reduced phosphorus uptake. Over the years, there has been