TY - JOUR AU - Pin, Sokornthea AU - Sreewongchai, Tanee AU - Onwimol, Damrongvudhi PY - 2019/10/31 Y2 - 2024/03/29 TI - Effects of Gibberellic Acid Applied at Different Flowering Stages on Agronomic Traits and Yields of Hybrid Rice Parental Lines JF - Science & Technology Asia JA - Sci Tech Asia VL - 24 IS - 4 SE - DO - UR - https://ph02.tci-thaijo.org/index.php/SciTechAsia/article/view/172130 SP - 126-134 AB - <p>Gibberellic acid (GA<sub>3</sub>) application in hybrid rice seed production plays a vital role in increasing seed yield; however, improper use of GA<sub>3</sub> may affect diversely the growth of hybrid parental lines. This study aimed to investigate the effects of GA<sub>3</sub> application at different flowering stages on agronomic traits and seed yield of hybrid parental lines. A micro-crossing plot experiment was employed for A line multiplication (HCS<sup>A</sup>/HCS<sup>B</sup>) under five treatments: applying GA<sub>3</sub> at 0%, 10%, 30% and 50% panicle heading stages and not applying GA<sub>3</sub>. The results indicated flag leaf length, number of internodes, length of base internode, spikelets per panicle, total dry biomass of both lines, panicle length of HCS<sup>A</sup> line and seed setting rate of HCS<sup>B </sup>line were not significantly different among the treatments. However, applying GA<sub>3</sub> at 10% panicle heading to 50% flowering stage significantly increased plant height, length of 1<sup>st</sup>, 2<sup>nd</sup>, and 3<sup>rd</sup> upper internodes, total length of these three upper internodes and panicle exsertion rate of these lines. Interestingly, applying GA<sub>3</sub> at 30% panicle heading stage enhanced A line to produce significantly higher panicle exsertion, stigma exsertion, and seed setting rates, ultimately leading to the highest seed yield of A line, while applying GA<sub>3 </sub>at 0% panicle heading stage slightly reduced panicle exsertion rate, and produced lower seed yield of both parental lines. These results suggest that applying GA<sub>3 </sub>at 30% panicle heading stage can be an effective method for increasing seed yield of A line. A verification test is necessary to confirm the present results.</p> ER -