Seed Health Management for Better Productivity - Govind Ballabh ...

(Seed Health Management for Better Productivity)the seed quality assurance. Different methods can be used to enhance seeds and seedlingperformances namelyi) Film-coating methods: It allows the chemicals to be applied in a synthetic polymer that issprayed onto the seeds and provide a solid, thin coat covering them. The advantage of thepolymers is that they adhere tightly to the seed and prevent loss of active materials like fungicides,nutrients, colorants or plant hormones. Some novel applications of film coating are used to modifyimbibitions and germination. They can confer temperature-sensitive water permeability to seeds oraffect gaseous exchange. By this they control the timing of seed germination and seedlingemergence.ii) Seed pelleting methods: This adds thicker artificial coverings to seeds, which can be used tocover irregular seed shapes and add chemicals to the pellet matrix, e.g. of sugar beet or vegetableseeds. The pellet matrix consists of filling materials and glue. Loam, starch, tyllose (cellulosederivative) or polyacrylate/polyacrylamide polymers are commercially used. Seed pelleting is alsoused to increase the size of very small horticultural seeds. This provides improved plantingfeatures, e.g. singulate planting, the use of planting machines, or precise placement and visibilityin/on the soil.iii) Seed Priming methods: It is the most important physiological seed enhancement method.Seed priming is a hydration treatment that allows controlled imbibition and induction of the pregerminativemetabolism ("activation"), but radicle emergence is prevented. The hydrationtreatment is stopped before desiccation tolerance is lost. An important problem is to stop thepriming process in the right moment; this time depends on the species and the seed batch.Molecular marker can be used to control the priming process. Priming solutions can besupplemented with plant hormones or beneficial microorganisms. The seeds can be dried back forstorage, distribution and planting. Germination speed and synchrony of primed seeds areenhanced and can be interpreted in the way that priming increases seed vigor. A widertemperature range for germination, release of dormancy and faster emergence of uniformseedlings is achieved. This leads to better crop stands and higher yields. A practical drawback ofprimed seeds is often a decrease in storability and the need for cool storage temperatures.Several types of priming viz. Osmopriming, Hydropriming and Matrixpriming are commonly used.i) Osmopriming (osmoconditioning) is the standard priming technique. Seeds are incubated inwell aerated solutions with a low water potential, and afterwards washes and dried. The low waterpotential of the solutions can be achieved by adding osmotica like mannitol, polyethyleneglycol(PEG) or salts like KCl.ii) Hydropriming (drum priming) is achieved by continuous or successive addition of a limitedamount of water to the seeds. A drum is used for this purpose and the water can also be appliedby humid air. 'On-farm steeping' is the cheep and useful technique that is practiced by incubatingseeds (cereals, legumes) for a limited time in warm water.- 190 -