Variation in production potential and physiological efficiency of different cropping systems under irrigated conditions

The experiment, consisting of ten cropping systems viz. rice-wheat, rice-berseem, rice-potato-wheat, rice-potato-sunflower, rice-wheat-green gram, sorghum (fodder, F)- wheat, sorghum (F)- toria-wheat, pigeonpea-wheat, maize-wheat and sugarcane ratoon-wheat, was conducted during 2000 (kharif) and 2001 (rabi) to find out most productive and physiologically efficient cropping system. Data on various physiological parameters revealed that, among all the systems evaluated, rice-potato-wheat was more efficient and productive as it gave highest biomass yield (27.13 t/ha), followed by sorghum (F)- wheat (26.1 t/ha), sorghum (F)- toria - wheat (25.0 t/ha) and sugarcane ratoon-wheat (22.2 t/ha). Rice-berseem, on the other hand, was lowest in terms of biomass potential (17.8 t/ha) and growth rate. This was largely appeared to be associated with leaf area, net assimilation rate (NAR) and relative growth rate (RGR) during flowering. Highest RGR and NAR were recorded in maize, pigeonpea and sorghum, during kharif, and in wheat, potato and sunflower, during rabi. Variation in biomass productivity among different cropping systems, were more associated with LAI (r = 0.84), RGR (r = 0.73) and NAR (r = 0.35), RGR, on the other hand, appeared to be associated with leaf area (r = 0.52) and NAR (r = 0.56), among different cropping systems. Production potential of different cropping systems, in terms of wheat equivalent yield (WEY), was significantly higher in rice-potato-sunflower (21 t/ha), followed by sugarcane ratoon-wheat (16.5 t/ha) and rice-potato-wheat (15.9 t/ha) than the rice-wheat sequence (9.4 t/ha). On the other hand, wheat equivalent yield was lowest in sorgftum (F)- wheat (9.1 t/ha) and maize-wheat (7.9 t/ha). Ricepotato- wheat, rice-potato-sunflower and sugarcane (ratoon)- wheat were more productive and efficient cropping system than others.