Nano seed technology is a new platform with endless possibilities and impacts on applied agriculture and forestry research. The implementation of nanotechnology in seed research is in its infancy and needs more pace to meet the needs of current global demand. Carbon nanotubes (CNTs) are allotropes of carbon and engineered nanomaterials. Based on the number of concentric layers of rolled graphene sheets, they are classified into single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs). CNTs exhibit both beneficial and toxic effects on plant species by altering the morphological and physiological properties of plant cells. In most of the studies, low concentrations of CNTs are considered safe. Therefore, there is plenty of room to use these cutting-edge technologies to alleviate seed dormancy, boost vigor, and solves the problem of slow growth in seed propagated species. This chapter summarizes the results of various studies investigating the effects of carbon nanotubes on seed viability, as well as seedling growth and biomass.
TopIntroduction
Seed is the most important and effective input for plant propagation. The quality of seed, which plays a critical role in the successful establishment of a plant population, determines the success of future plant development. Many factors influence the quality of a seed, including its physical, physiological, genetic, and health status. Good processing procedures can increase the physical quality of any seed. Similarly, good breeding procedures and proper rouging of undesired plants, as well as scientific seed generation chain maintenance, can improve the genetic and health quality of a seed. The planting value (germination and vigour) of a seed determines its physiological quality, which can be improved using various seed quality enhancement technologies (Villa et al., 2019). Seed germination is the most important step in initiating a physiological process that requires plant growth and water intake (Adhikari et al., 2013). This is determined, among other things, by the amount of water accessible during the seed coat penetration and germination cycle seed maturity, and surrounding growth conditions (Khodakovskaya et al., 2012). Seed vigour is a key metric for evaluating seedling quality, storability, emergence, and establishment under a variety of environmental and natural circumstances.
Seed dormancy is a situation in which seeds cannot germinate under otherwise ideal germination conditions.. There are three types of dormancy in seeds: a) strong seed coatings that are not only impervious to water and gases, but also restrict embryo expansion (physical dormancy). b) The second is embryo or internal dormancy, which occurs when seeds have small and underdeveloped embryos that do not germinate after ripening. c) Germination inhibitors, which prevent seed germination and plant growth, induce the third seed dormancy. These inhibitors must be laeched out (Kobayashi et al., 2010). Finding efficient techniques to relieve seed dormancy in numerous forest species and enhance their use and success in forest restoration is essential. Germination rates of rosemary seeds with hard seed coats, embryos and physiological seed dormancy are increased by low temperature stratification after maturation, incubation with gibberellic acid (hormone priming), seed coat scarring and inhibitor leaching. Acid scarification, which is used to break seed coat-induced dormancy, can harm seedling growth and is not environmentally friendly. Yucel (2000a) studied the effects of different NaCl, KN03, and H2SO4 concentrations on the germination rate of six Salvia species. The proportion and rate of H2SO4 on germination that is hazardous is reported. As a result, acids must be replaced with safer chemicals.
Pre-sowing, pre-storage, and mid-storage treatments are examples of seed enhancement technologies (SETs) that are widely employed in today's seed science and technology (Sharma et al., 2015). Scarification, stratification, seed pelleting, seed priming, seed coating, and seed protection are all used as pre-planting treatments to break dormancy, increase germination, and for precision sowing of seeds (Ahmed and Kumar 2020). Pre-storage and mid-storage treatments are used to improve or maintain the viability and vigour of seeds while they are being stored. Seed priming is a pre-sowing seed preparation that helps seeds to be hydrated and proceed through the first stage of germination while preventing radical protrusion through the seed coat (McDonald, 2000). It comes in a variety of forms, including hydropriming, osmopriming, halopriming, hormonal priming, and biopriming (See Figure 2). Despite the fact that these seed treatment methods have been used for a long time to improve seed growth, they have a number of drawbacks. Traditional seed priming systems are plagued by inconsistency, the need for repeated treatments, and a huge waste of priming material (Tsuji, 2001). To overcome the challenges given by existing approaches, a prospective alternative seed growth enhancement methodology is required.