Climate resilience key to curbing yield losses

The transplanting of PUSA 44 paddy variety should be avoided as it takes a longer time to mature and usually delays the sowing of the subsequent wheat crop. Always use 40-kg seed per acre; however, for PBW 869 and Unnat PBW 550 varieties, 45-kg seed per acre should be used. The seed should be purchased from a reliable source, preferably PAU or govt seed-producing agencies. The farmers are advised to use certified seed in case these are procured from private agencies.

Hari Ram and Satbir Singh Gosal

WHEAT crop requires low temperature and less humidity during the early stages for better tillering. The mild temperature during the grain-filling stage helps in the proper ripening and grain filling of the crop. The sudden rise of 2.1-6.6°C in the minimum temperature and 2.6-6°C in the maximum temperature in March became unfavourable for the crop.

High temperature impacts the enzyme system of the crop for early maturity, which leads to shrivelled grains and less yield. The productivity in Punjab during 2021-22 (42.11 quintals/hectare) was reduced by 13.5% than the productivity in 2020-21. The same trend of lower productivity was also seen in other wheat-bowl states. At the national level, the wheat production was 109.6 million tonnes in 2020-21; it was reached only 105 million tonnes in 2021-22.

The first fortnight of November is the optimum sowing time for better productivity; however, the sowing of long-duration varieties should be started from October 25. Delayed sowing after November 15 results in a 1.5 quintals/acre per week reduction in grain yield. The transplanting of PUSA 44 paddy variety should be avoided as it takes a longer time to mature and usually delays the sowing of the subsequent wheat crop. Always use 40-kg seed per acre; however, for PBW 869 and Unnat PBW 550 varieties, 45-kg seed per acre should be used. The seed should be purchased from a reliable source, preferably PAU or government seed-producing agencies. The farmers are advised to use certified seed in case these are procured from private agencies. If the farmers are using their own seed, then these should be cleaned, properly graded, be free from other crop/variety seeds, free from diseases, especially seed-borne ones like Karnal bunt. Under irrigated conditions, PBW 826 (newly identified variety of PAU from Jammu to Assam), PBW 869 (for Happy Seeder and Super Seeder), PBW 824, PBW 803, PBW 766 (Sunehri), PBW 1 Chapati, Unnat PBW 343, DBW222, DBW 187, HD 3226, Unnat PBW 550, PBW 1Zn, PBW 725 and PBW 677 varieties have been recommended. Under irrigated conditions of the submontane Punjab, farmers must raise PBW 725, Unnat PBW 550 and PBW 677 varieties due to their higher resistance to yellow rust.

According to a survey conducted in Punjab during 2022 by PAU, wheat variety PBW 766 (Sunehri) performed better in 15 districts of the state with less reduction in grain weight and the yield even under the high temperature conditions that prevailed earlier this year. PBW 766 (Sunehri), PBW 826, PBW 824, PBW 869 and PBW 725 are climate-resilient varieties and have better heat susceptibility index. Paddy straw management with machines helps in timely sowing, reduces pollution, saves energy, improves input use efficiency, lowers weed growth, reduces lodging, yellowing after first irrigation and the cost of production. If the paddy straw is removed, the crop can be sown with the seed-cum-fertiliser drill in conventionally tilled field and with zero-till drill in no-tilled fields. The seed should be placed 4-6 cm deep with a row-to-row spacing of 15-20 cm.

Wheat can be sown directly in the standing paddy stubble with the help of Happy Seeder or PAU Happy Seeder with press wheel attachment or Super Seeder or Smart Seeder. Mulching protects the loss of moisture from the soil surface and keeps the crop canopy cooler. Retention of mulching in very heavy soil should be avoided, otherwise after the first irrigation or heavy rain, the crop will show yellowing due to less aeration in the soil. Always use organic manure like farmyard manure, poultry manure, gobar gas slurry, rice husk or bagasse or grow green manuring crops like dhaincha or sunhemp for improving soil health by increasing organic matter and reducing the farmer’s dependence on chemical fertilisers.

In conventionally tilled medium-fertility soils, apply 55 kg DAP/acre and 90 kg urea/acre to the wheat crop. Apply whole DAP at the time of sowing, the half dose of nitrogen at the first irrigation and the remaining half can be top-dressed at the second irrigation. Apply DAP @65 kg/acre at the time of sowing in Happy Seeder/PAU Happy Seeder/Smart Seeder-sown crop. Apply half urea before sowing and the remaining before the first irrigation. Complete the sowing of the crop up to November 15 to protect it from high temperature stress. The high temperature stress effect can be minimised through the application of 2% potassium nitrate by dissolving 4 kg potassium nitrate in 200 litres of water at boot leaf and anthesis stage during the evening hours. These sprays increase the crop duration and enhanced the grain yield. Always try to give pre-sowing irrigation. The pre-sowing irrigation can be given to standing paddy 5-10 days before harvesting if soil moisture is less.

The first irrigation should be light and be given three weeks after sowing to October-sown crop and four weeks after sowing if the crop is being sown later. The subsequent irrigations can be applied at 4-5 weeks’ interval, depending upon the soil type and temperature. If temperature rises at the grain-filling stage, give light irrigation immediately. So, farmers are advised to complete the sowing of wheat by November 15 using recommended varieties with any sowing method as per availability and prevailing conditions along with proper fertilisation, irrigation management and protective foliar application of nutrients to realise the production potential of wheat under the changing climate scenario.

Hari Ram is Principal Agronomist (Wheat), PAU; Gosal is Vice-Chancellor