Effect of Seeding Dates, Rates of Nitrogen and Manipulator on Wheat and Barley

Two field experiments were conducted; one on wheat and another on barley during 2021, 2023 and 2024 in split plot design replicated four times. Main plots treatments included 4 seeding dates (first earliest possible seeding date in spring and later at weekly intervals) and sub plot treatments included combinations of two rates of N (80 and 160 kg N ha-1) and two rates of Manipulator (chlormequat) @ 1.8 l ha-1 in wheat and @ 2.3 l ha-1 in barley at complete tillering. Averaged over 2021, 2023 and 2024, maximum grain (4.33 Mg ha-1) and biomass (9.2 Mg ha-1) yields were recorded with seeding on May 8, with application of N @ 80 kg ha-1 and no Manipulator spray. Whereas, maximum straw yield (6.25 Mg ha-1) was registered by May 30 seeding, with application of 160 kg N ha-1 and spray of Manipulator. Increasing N rate from 80 to 160 kg ha-1 or spraying Manipulator didn’t significantly improve the grain yield, though Manipulator spray reduced the plant height by 4 cm. In barley, averaged over 2021, 2023 and 2024, grain yields were maximum with May 8 (5.19 Mg ha-1) or May 15 (5.18 Mg ha-1)

seedings. However, the straw (5.72/5.65 Mg ha-1) and biomass (10.2/10.4 Mg ha-1) yields were higher with the later seedings. Increasing the rate of N application from 80 to 160 kg N ha-1 significantly improved the straw yield, but not the grain and biomass yields. Manipulator spray had no impact on grain, straw or biomass yields, though Manipulator spray reduced the plant height by ~3 cm.