Plant breeders evaluate large numbers of breeding lines/accessions and measure various traits in the field in order to identify and select elite genotypes with high yield. Therefore, information on highly correlated yield-related traits and simple high-throughput methods to predict grain yield would be useful for rice breeders. The objective of this study was to examine the usefulness of various traits as indirect selection criteria for high yield in tropical rice breeding, with an emphasis on rapid and non-destructive measurements. We evaluated a wide range of germplasm, including popular varieties, elite genotypes, and donor parents, in the irrigated rice breeding program at the International Rice Research Institute, in the Philippines, during the 2015 wet season and 2016 dry season. We measured the normalized-difference vegetation index (NDVI), leaf chlorophyll content (SPAD value), agronomic traits, and grain yield. Harvest index, NDVI at the heading and late grain-filling stages, and SPAD value at the late grain-filling stage were significantly correlated with yield during the wet season, whereas plant height, panicle length, and NDVI from panicle initiation to the booting stage during the dry season. Our results indicate that pre-harvest analysis of primary and secondary traits such as NDVI has potential for selecting high-yielding accessions in tropical rice breeding programs. By using low-cost portable equipment, NDVI measurements could be incorporated into breeding programs. Trait associations with yield differed between the dry and wet seasons, which has important implications for breeding new varieties and germplasm evaluation in different seasons.

中文翻译：

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NDVI在热带水稻育种高产间接选择中的应用

植物育种者评估大量育种品系/种质并测量田间的各种性状，以识别和选择高产的优良基因型。因此，高度相关的产量相关性状信息和预测谷物产量的简单高通量方法对水稻育种者很有用。本研究的目的是检查各种性状作为热带水稻育种高产间接选择标准的有用性，重点是快速和无损测量。我们在菲律宾国际水稻研究所的灌溉水稻育种计划中，在 2015 年雨季和 2016 年旱季评估了广泛的种质，包括流行品种、优良基因型和供体亲本。我们测量了归一化差异植被指数 (NDVI)，叶叶绿素含量（SPAD 值）、农艺性状和谷物产量。收获指数、抽穗期和灌浆后期的NDVI、灌浆后期的SPAD值与雨季产量呈显着相关，而株高、穗长和穗长至孕穗期的NDVI在旱季。我们的结果表明，对 NDVI 等主要和次要性状的收获前分析具有在热带水稻育种计划中选择高产种质的潜力。通过使用低成本的便携式设备，NDVI 测量可以被纳入育种计划。性状与产量的关联在旱季和雨季之间存在差异，这对不同季节的新品种选育和种质评价具有重要意义。