Field experiments were conducted for the three consecutive cropping seasons of 2003-05, 2004-06 and 2005-07 at the Indian Institute of Sugarcane Research, Lucknow, India, to explore the feasibility of planting sugarcane in autumn as a relay intercrop in standing rice. The cropping systems evaluated were: (i) rice-potato-spring sugarcane; (ii) rice+autumn sugarcane (planted as a relay intercrop in every sixth row devoid (skipped) of transplanted rice)+potato after rice; (iii) rice-autumn sugarcane (planted without preparatory tillage)+potato; and (iv) rice-autumn sugarcane (planted with preparatory tillage)+potato. In each case, sugarcane was planted in rows 90 cm apart. Rice was transplanted in rows at 20-cm row spacing when followed by potato or sugarcane, but at 18-cm row spacing when intended for sugarcane planting as a relay intercrop in late September. The germination (60.4%) of cane buds, tillers (323 000 ha -1) and number (149 000 ha -1), length (225 cm), girth (2.44 cm) and weight (747 g) of millable canes were markedly better when autumn sugarcane was planted with rice as a relay intercrop in comparison to other cropping systems. Similarly, this cropping system produced the maximum cane (111.4 t ha -1) and sugar (13.2 t ha -1) along with sugarcane equivalent yield (216.4 t ha -1). In turn, relay intercropping system with maximum cane production efficiency of 420 kg ha -1day -1 fetched the highest economic returns (Rs. 258 ha -1day -1) and benefit:cost ratio (1.5). Compared with the rice-potato-spring sugarcane cropping system, the relay intercrop of autumn sugarcane in standing rice produced 35.4% more cane and 38.3% more sugar with 24.1% higher returns besides 79.1% energy saving. This practice will not only benefit cane growers and sugar mill owners in tropical and sub-tropical India, but also in other parts of the world where rice and sugarcane are extensively cultivated.
