W heat is a major grain crop and primary staple food of Pakistan and it is a major source of carbohydrates and energy (Chattha et al., 2017a (Chattha et al., , 2018 . The seed of wheat contains 2.11% minerals, 68% carbohydrate, 2.9% fat, 15.4% proteins and an important source of calories and micro-nutrients Abstract | Delayed wheat sowing is the main factor responsible for the lower yield of wheat owing to low temperature during emergence and early growth. Seed size has an appreciable potential

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... to improve stand establishment, growth, and yield under late sowing conditions. Therefore, the present study was performed to assess the impact of diverse seed sizes (SS) on the growth and yield of wheat crop under late sowing conditions. The study was comprised of different sowing dates (SD), SD 1 : 15 th December, SD 2 : and 30 th December and different seed size classes i.e. bold (having a diameter of > 2.7 mm), medium (having a diameter of > 2.3 mm to 2.7 mm), small (having a diameter of ≤ 2.3 mm) and mixed seeds. The results indicated that different sowing dates and seed size classes had a significant effect on germination, growth, and yield of wheat crop. The crop sown on 15 th December took less time to start emergence (7.8 days) and resulted in maximum plant height (81 cm), grains per spike (44.5), productive tillers (321.5), spike length (10.2 cm), 1000 grain weight (37.2 g), and grain yield (3.83 t ha -1 ) and maximum time to start emergence (11 days) and minimum plant height (60 cm), grains per spike (35.7), productive tillers (273), spike length (8.6 cm), 1000 grain weight (32 g), and grain yield (2.7 t ha -1 ) was recorded in the crop sown on 30 th December. In the case of seed size classes, bold seed performed appreciably well and took less time to start emergence (8.5 days) and had more plant height (74.7 cm), productive tillers (326), spike length (10.1 cm), grains per spike (45), 1000 grain weight (37 g), and grain yield (3.67 t ha -1 ) compared to other seed size classes. In conclusion, bold seed size can significantly improve the wheat production under late sown conditions due to better stand establishment, vigorous germination, and increase in yield related traits.