Flooding is one of the major constraints for rice production in rainfed lowlands, especially in years and areas of high rainfall. Incorporating the Sub1 (Submergence1) gene into high yielding popular varieties has proven to be the most feasible approach to sustain rice production in submergence-prone areas. Introgression of this QTL into popular varieties has resulted in considerable improvement in yield after flooding. However, its impact under non-flooded conditions or years have not been thoroughly evaluated which is important for the farmers to accept and adopt any new version of their popular varieties. The present study was carried out to evaluate the effect of Sub1 on grain yield of rice in different genetic backgrounds, under non-submergence conditions, over years and locations. The study was carried out using head to head trials in farmer’s fields, which enable the farmers to more accurately compare the performance of Sub1 varieties with their recurrent parents under own management. The data generated from different head to head trials revealed that the grain yield of Sub1 varieties was either statistically similar or higher than their non-Sub1 counterparts under non-submergence conditions. Thus, Sub1 rice varieties show no instance of yield penalty of the introgressed gene.

Shivalik region is sandwiched between Himalayan ecosystem and Indo-Gangetic plains in northwestern India. However, its area is reported to range from 2.14 to 8.00 m ha in northwestern India by different workers. Based on geology and physiography, we demarcated the Shivalik region (3.33 mha), covering hills (1.79 mha) and its piedmont plains or foot hills (1.54 m ha) in the states of Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Punjab, Haryana, Uttar Pradesh and union territory of Chandigarh at an elevation ranging from 217 to 2332 m above MSL. The delineated map showing Shivalik region will be useful in conserving the natural resources of the region without any dispute over its location and area.