Short-duration varieties are turning the tide

Buta Singh Dhillon and Ranvir Singh Gill

RICE is a staple of the diet of more than 60 per cent of the global population. In India, rice was grown on 44.19 million hectares during 2020-21; the country exported 17.71 million metric tonnes (MT) of rice to countries such as Iran, Saudi Arabia, Vietnam, USA, Nepal, Benin, Somalia and Guinea. Sustainability of the rice production system in India is important for ensuring global food security. Rice is the predominant kharif crop of Punjab, occupying about 75 per cent of the total cultivated area in the state during this cropping season. Punjab has made remarkable progress in the production and productivity of rice during the past 50 years.

With the substantial increase in area and productivity of paddy, there is concurrent increase in paddy residue. At present, 23 to 24 million tonnes of paddy residue is being produced every year in Punjab. Overexploitation of groundwater in paddy-growing areas is another major challenge threatening the sustainability of irrigated agriculture in the region. In addition to inherent high-water requirement of the paddy crop, early transplanting of rice (before mid-June), aggravates the groundwater fall as the evapo-transpiration during June is very high. The average rate of water table fall in Punjab is about 53 cm/year, but in some central districts, it is almost 100cm/year. Keeping in view these concerns/issues, scientists at PAU reshaped their breeding strategies towards development of short to medium-duration varieties with higher per-day productivity, low paddy residue and a longer window between harvesting of paddy and sowing of rabi crops.

Targeted research at Punjab Agricultural University (PAU), Ludhiana, has led to the development of short to medium-duration varieties. Since 2013, PAU has recommended 10 varieties of paddy for general cultivation in the state (PR 121, 122, 123, 124, 126, 127, 128, 129, 130 and 131) which mature in as less as 93 days after transplanting (PR 126) to the maximum of 117 days after transplanting (PR 122). But most of these mature between 105 and 110 days after transplanting. On account of their shorter duration, low straw load, high yield and resource-conserving nature, the varieties recommended by PAU are becoming the choice of farmers, covering about 70 per cent of the area concerned in the state.

The short-duration varieties recommended by PAU have lesser straw load as compared to long-duration ones. Crop residue of short-duration/early-maturing varieties or those having lesser straw load can be managed quite efficiently with various resource conservation technologies. However, the farmers cultivating long-duration varieties tend to resort to residue burning owing to the shorter window available for sowing of the next crop as well as higher straw load of these varieties. The window between harvesting of rice and wheat-sowing is 22 to 27 days in the case of PR 121, PR 130 and PR 131, which extends further up to 25 to 40 days in case of PR 126 but Pusa 44 (a long-duration variety) offer only 0-5 days’ window between harvesting of rice and wheat-sowing.

The short-duration varieties, besides offering a sufficient window for paddy residue management, also save irrigation water and input cost. In spite of all these benefits, the selection of long-duration varieties by farmers is associated with the perception that owing to their higher yield, they are more profitable. But this perception does not hold true when we evaluate the economics of growing these varieties by taking into account various inputs and operations. Moreover, the cultivation of short-duration varieties offers scope for the adoption of multiple cropping systems.

Since the development of short-duration varieties and extension efforts for their adoption, the area under these varieties has increased considerably in Punjab. The data clearly indicates that with the increase in the adoption of short-duration varieties over the years, there is a rise in the production and productivity of paddy. It is due to the high productivity potential of these varieties.

Though the short-duration varieties have been well adopted by the farmers in the state, in the districts of Barnala, Bathinda, Ludhiana, Mansa, Moga, Muktsar Sahib and Sangrur, the adoption is slow and a sizeable area (40-60 per cent) is under long-duration varieties. It has been observed that the incidence of residue burning was higher in the districts having more area under long-duration varieties (Sangrur, Bathinda, Muktsar Sahib, Mansa, Barnala, Moga and Ludhiana). Besides this, the rate of fall in the water table (except Muktsar Sahib) is also significantly higher in these districts.

Water conservation

Research-based enactment of the Punjab Preservation of Sub-soil Water Ordinance/Act (2008/2009) permits paddy transplantation from June 10. This date was revised to June 15 in 2014 and it caused no yield handicap. Rather, successive record yields were observed in 2016 and 2017. During these years, the adoption of shorter-duration varieties offered the opportunity of shifting the transplanting date further close to the onset of monsoon and the date was pushed to June 20 during kharif-2018. Data of our research experiments in the foregoing years has shown this shift to be a win-win option in terms of productivity and water-saving, while ensuring a sufficient period between harvesting of paddy and sowing of succeeding rabi crops.

Thus, the development and adoption of short-duration high-yielding varieties having low straw load are becoming an integral component of the strategies oriented towards the success of efficient straw management technologies as well as water-saving interventions.

Dhillon is Agronomist (rice) and Gill is Principal Rice Breeder at PAU, Ludhiana