Reproductive Development and Yield Components of Bario Sederhana Rice in Response to Photoperiod

Abstract

A series of controlled environment treatments were conducted to quantify reproductive development and yield components of Bario Sederhana rice grown under five photoperiod regimes (8, 9, 10, 11, & 12 h). A ‘broken-stick’ linear regression of heading rate against photoperiod was used to determine the cardinal photoperiods for heading.  The reproductive development towards photoperiod showed a delayed pattern in time to heading, anthesis, and maturity under lengthening photoperiod from 10 to 12 h.  For example, under 10 h photoperiod the crops required 1680 °Cd (70.8 days) from emergence to heading but took an extended duration of 3147 °Cd (132.6 days) when they were sown at 12 h photoperiod. The prolonged time taken for reproductive development modified by photoperiod resulted in higher yield components. This is because the lengthening time from heading to maturity extended the duration of grain filling. The longest photoperiod of 12 h gave the highest percentage of filled spikelets (65.3%) thus consequently leading to the heaviest grain weight of 1.4 g per panicle. The base, optimum, and maximum photoperiod for heading were estimated to be 7.4 h, 10 h, and 14.8 h, respectively.