A mono-layer matrix for pelleting marigold (Tagetes erecta) seeds

Abstract

Marigold growers in Thailand face challenges in the cultivation from seeds of marigold owing to the elongated, slender and sometimes fragile shape of the seeds. These characteristics often result in a high number of seedlings with abnormal traits, making them susceptible to diseases and insects. The objective of this study was to develop a pellet formulation for marigold seeds to increase their size and facilitate cultivation from seeds. Seven pellet matrices, including a commercial product (pre-pelleted seeds), were assessed for integrity, including friability, dissolution period germination, shoot length, and root length under both laboratory and greenhouse conditions. Methylhydroxyethyl cellulose (MHEC) was used as the binding agent for each pellet matrix. Seeds pelleted with MHEC-bentonite and MHEC-zeolite resulted in irregularly shaped pellets, whereas the other matrices appeared smoother and more similar to commercially-pelleted seeds. CaCO3 and talc-pelleted seeds had a high friability, whereas CaSO4-, pumice- and bentonite-pelleted seeds had friability values similar to those of the commercially-pelleted seeds. CaSO4-pelleted seeds exhibited germination rates that were the closest to those of non-pelleted and commercially-pelleted seeds under both laboratory and greenhouse conditions. In conclusion, the MHEC-CaSO4 matrix is the most suitable choice for pelleting marigold seeds.