Characterizing the Environmental Response of a Gibberellic Acid–Deficient Rice for Use as a Model Crop

Abstract

Rice (Oryza sativa L.) is a useful model crop plant. Rice was the first crop plant to have its complete genome sequenced. Unfortunately, even semidwarf rice cultivars are 60 to 90 cm tall, and large plant populations cannot be grown in the confined volumes of greenhouses and growth chambers. We recently identified an extremely short (20 cm tall) rice line, which is an ideal model for larger rice cultivars. We called this line ‘Super Dwarf’ rice. Here we report the response of Super Dwarf to temperature, photoperiod, photosynthetic photon flux (PPF), and factors that can affect time to head emergence. Vegetative biomass increased 6% per degree Celsius, with increasing temperature from 27 to 31°C. Seed yield decreased by 2% per degree Celsius rise in temperature, and as a result, harvest index decreased from 60 to 54%. The time to heading increased by 2 d for every hour above a 12‐h photoperiod. Yield increased with increasing PPF up to the highest level tested at 1800 μmol m−2 s−1 (12‐h photoperiod; 77.8 mol m−2 d−1). Yield efficiency (grams per mole of photons) increased to 900 μmol m−2 s−1 and then slightly decreased at 1800 μmol m−2 s−1. Heading was delayed by addition of gibberellic acid 3 (GA3) to the root zone but was hastened under mild N stress. Overall, short stature, high yield, high harvest index, and no extraordinary environmental requirements make Super Dwarf rice an excellent model plant for yield studies in controlled environments.