Quality Evaluation of Coated Extra-Large Hulled Sunflower (Helianthus Annuus) Kernels for Precision Planting
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Abstract
Domestic and export demand for extra-large (XL) in-shell confectionary sunflower seeds (Helianthus Annuus) growing; however, a significant proportion of the hybrid seed for planting goes to the snack food market because the extra-large seed is not acceptable to farmers. The extra-large hybrid seed has poor emergence in the field and is not compatible with precision planters. Therefore, the option of coating the hulled sunflower kernels for improved germination and plantability is investigated in this dissertation. Twenty types of kernel coatings have been tested, through collaboration with five seed coating companies and development of our own in-house seed coating capabilities. Coated kernels were tested for germination, seedling vigor, and other indicators of kernel viability. Coated kernels were also tested for plantability using a precision planter test stand. The top-performing coated kernels achieved singulation and post-singulation germination comparable to large planting seed used by farmers. A field trial was conducted in 2017 at Prosper, ND with eight types of coated kernel treatments having zeolite, lime, Polymer A, and Polymer B In-house coating materials each at 30% and 35% build-up levels. Coated kernels produced grain yields up to 55% greater than from XL seeds, and up to 25% greater than large seeds. Live seed emergence of all the coated kernels (93 – 99%) was significantly higher than the XL seeds (88%) and similar or higher than the large seeds (94%). Another small-scale field trial was conducted at Minot, ND, where moisture stressed conditions were observed. Coated kernels showed similar trends to the Prosper location both in terms of live seed emergence and grain yield as compared to XL seeds. Further, an automated image processing method was developed form the RGB images taken with an unmanned aerial vehicle which predicted the emergence counts and a number of multiples in every row of the sunflower field trial at Prosper with R2 of 0.94 and 0.92. Overall, coated kernels showed significant improvements in achieving plant stand uniformity compared to XL seeds.