Validation of root growth simulation models for cotton crop grown under specified environment

The cotton root growth was observed through vertical soil column studies. The maximum root depth of 175cm was attained at 180 DAS. However, rooting depth of 148 cm could be obtained at 120 DAS only. It was observed that major part of total root length was concentrated within 30cm up to 80 DAS and within 60cm up to maturity. The root depth data were fitted to models such as Rasmussen and Hanks (1978), Hanks and Hill (1980), Reuss (1980) Fereres et al. (1981), Borg and Grimes (1986) Schouwenaars (1988), and Subbaiah and Rao (1994), by regression analysis. Among these, the model of Rasmussen & Hanks was found the best fitted, followed by Hanks and Hill, Subbaiah and Rao, Borg and Grimes, Fereres et al., Reuss and Schouwenaars.