DEVELOPMENTAL AND PHENOLOGICAL RESPONSES OF WHEAT TO SOWING DATES

This study was conducted to study the developmental and phenological responses of different wheat cultivars planted at varying sowing dates. Five wheat cultivars viz. Sahar-2006 (SH-06), Faisalabad-2008 (FSD-08), Lassani-2008 (LS-08), Abdul Staar-2002 (AS-02) and Triple Dwarf-1 (TD-1) were sown on 25th Oct, 10 and 25th Nov, and 10th and 25th Dec. Minimum days to emergence and tillering were recorded in early planted wheat. In comparison late planted wheat took less time to switch into other phenophases like jointing, booting and grain formation stages due to high temperature during lateral growth stages of late planted wheat. Likely, early planted wheat accumulated less growing degree days (GDD) and photo thermal units (PTU) for emergence but accumulated more GDD and PTU to switch into next phenophases from tillering to grain development. Nonetheless late planted wheat required more helio-thermal units (HTU) only during grain formation stage. However, total growth period of wheat was substantially decreased from 166 days in early planted (25th Oct) to 110 days in late planted (25th Dec) being a photosensitive in nature. Tested wheat cultivars behaved differently and LS-08 and AS-02 had higher grain yield and heat use efficiency (HUE) due to higher tillering capacity and longer growth period, whereas performance of short duration cultivar (TD-1) was poor. In conclusion, wheat cultivars LS-08 and AS-02 planted on 10th Nov produced more grain yield and had higher HUE.