Muhammad Muharram, Agus Suryanto, Sudiarso, Anna Satyana Karyawati
Rice production stability is essential to maintain Indonesia’s food security, yet it is increasingly affected by climate variability. This study quantified thermal time as growing degree days (GDD) and radiation use efficiency (RUE) to evaluate rice performance across wet-season planting windows and to identify a suitable planting period for tropical lowland ecosystems. The field investigation was carried out in Sidoarjo, East Java, Indonesia, during the 2023–2024 wet season using three representative varieties: Pandan Wangi, Inpari 32, and Intani 602. Rice was transplanted at three planting periods representing early (November), mid (January), and late (March) wet season planting. The experiment applied a randomized block design with two factors with combine anlyzed. Data were analyzed using analysis of variance and regression. The results indicated that planting time significantly affected all yield components. The hybrid Intani 602 achieved the highest panicle number, grain weight, and grain yield (7.56 to 9.54 t ha⁻¹), demonstrating superior adaptability and physiological performance. Regression analysis showed a significant negative relationship between GDD and grain yield and a positive relationship between RUE and grain yield. The findings emphasize the importance of matching variety selection with planting time to enhance productivity and resilience under tropical climates. Developing suitable agroclimatic-based planting calendars is recommended to support sustainable rice production systems. © 2026, Association of Agrometeorologists. All rights reserved.
Department of Agronomy, Faculty of Agriculture, Brawijaya University, Malang, 65145, Indonesia
