Cost analysis on assessing the purity of rice hybrids: grow-out test vs. marker-based test
2012
Maoirat, M.R. | Rigor, A.T., Philippine Rice Research Inst. Maligaya, Science City of Mu�oz, Nueva Ecija (Philippines). Plant Breeding and Biotechnology Div.
It is estimated that for every 1% impurity in the hybrid seeds, the yield reduction is 100 kg per hectare (Mao et. al., 1996). Therefore, purity of seeds is a major factor to consider to fully exploit the yield potentials of hybrids. At PhilRice, assessment of seed purity of hybrid rice seeds before dispatch is done using grow-out tests (GOT), which is based on the morphological assessment of the plants grown to maturity. GOT results should be reliable before seed dispatch, as legal disputes can arise if it turns out that the contracted seeds do not have the required level of seed purity. The objective of this study is to assess the comparative cost between using grow-out testing and marker-based testing in determining purity of hybrid seeds. Four public-bred hybrids-mestiso 1, mestiso 19, mestiso 20, and mestiso 21 were used in this study. Six SSR markers were used to analyze 96 randomly selected samples per entry in three replicates. A 1,000-plant grow-out test plot (replicate) at PhilRice Los Ba�os was used for the cost comparison. The cost for marker-based testing (MBT) was Php 62,314.56 per variety whereas an estimate of Php 28,000 is needed for GOT. For seed companies, large amount of their income is locked up in the form of hybrid rice stocks while waiting for the season-long result of GOT. Using MBT method, in three weeks time, percent off-types will be detected, making it more accurate, fast and practical to use for assessing seed purity. Detecting a single reliable marker that can be used for each hybrid to assess seed purity can be a major plus factor to further reduce the cost of MBT.
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