Root growth during formative phase in irrigated and water stressed sugarcane and its relationship with shoot development and yield

The sett and shoot-root growth in relation to shoot dry matter and yield was evaluated in ten normally irrigated and water stressed (60 to 150 days) sugarcane (Saceharum sp.) varieties. The first formed sett-roots which reached a maximum length of 13.7 cm were replaced by a potential shoot-root system by 150 days age. An average reduction of 59.6% in total root weight and 49.9% in total root length at 150 days under stress was associated with 66.4% 64.5% and 87.3% reduction in leaf, leaf sheath and stem dry matter, respectively, at 150 days, or a reduction of 19.2%, 32.7% and 15.0% in cane yield, sugar yield and sucrose % juice, respectively, at harvest. The low shoot/root ratios in water stressed plants suggested a higher root growth than shoot component. Foliage development was faster during rehydration, while stem growth remained low upto 300 days in stressed plants. Roots penetrated deep in response to stress ond a typical rope type root system occurred in variety Co 285. It was observed that shoot-roots but not the sett-roots had positive association with growth and yield. A greater root weight and root system that extends sufficiently deeper are some of the characters which help alleviate the stress effect during the critical water demand period.