Hydration curve and physiological quality of maize seeds subjected to water deficit

Abstract

The hydration pattern associated with the physiological quality of seeds can be an early indicator for the evaluation of seed quality. The present study aimed to evaluate the hydration pattern of seeds subjected, or not, to water restriction, and to relate these patterns to their physiological quality. The physiological quality of seeds from five maize strains (L1, L2, L3, L4, and L5) and four hybrids (HT1, HT2, HS1, and HS2) was initially determined using seed germination and vigor tests (accelerated ageing and electric conductivity). A completely randomized experimental design was used with four repeats for the physiological analyses and a regression analysis was performed in order to assess the behavior of the seeds over time. The hydration curve was determined by imbibing the seeds in distilled water (0.0 control) and in a -0.9-MPa osmotic solution of polyethylene glycol 6000. Water uptake by the seeds was found to follow a triphasic pattern in the absence of water stress (0.0 MPa); however, when exposed to a -0.9- MPa osmotic potential, an extended phase II was observed. Diversity was observed between the strains in terms of the hydration pattern of the seeds, which can influence the physiological quality of the hybrid seeds. Regarding the hybrids, a positive relationship was observed between the shortest time to root protrusion and the quality of the seeds, both with or without water restriction, which allows us to conclude that hydration pattern can be used as a parameter for the early evaluation of physiological quality in hybrid maize seeds.

Osmolyte accumulation and antioxidant metabolism during germination of vigorous maize seeds subjected to water deficit

“…Similar trends have been reported by other researchers, who found a significant decline in the germination capacity of maize seeds as a function of reduced osmotic potential caused by polyethylene glycol 6000, helping to identify drought-resistant maize genotypes (Khayatnezhad, Gholamin, Jamaati-e-Somarin, & Zabihi-e-Mahmoodabad, 2010;Vaz-de-Melo et al, 2012;Abreu et al, 2014;Partheeban, Chandrasekhar, Jeyakumar, Ravikesavan, & Gnanam, 2017), as observed in the present study.In hydration with water, hybrid HT1 achieved protrusion in 36 hours and HT2 achieved protrusion in 48 hours; at -0.3 MPa, HT1 obtained protrusion in 48 hours and HT2 in 96 hours; and at -0.9 MPa, protrusion occurred in 72 and 168 hours for HT1 and HT2, respectively. According to Prazeres and Coelho (2017), root protrusion was achieved in less time in the high vigor hybrid (HT1) than its low vigor counterpart (HT2) for all of the osmotic potentials. Root protrusion was used as a reference point for the mobilization of the stored reserves.…”

“…Both hybrids were produced in the 2015/2016 growing season and provided by a local company in the municipality of Coxilha in the state of Rio Grande do Sul. Both were previously characterized in terms of vigor according to Prazeres and Coelho (2017). The HT1 hybrid showed higher germination (96%), higher vigor by accelerated aging (89%) and a low electrical conductivity (10.81 μS cm -1 g -1 ).…”

Effects of static magnetic fields on onion (Allium cepa L.) seed germination and early seedling growth

“…This limitation of magnetic stimulation had already been reported; for this reason, there was no positive effect from the applied magnetic fields on the germination of onion seeds in studies carried out by Tkalec et al (2009). This may be because the use of electromagnetic fields in seeds alters the rate of water transport to the seed; it slows down germination, and it is directly dependent on hydration (Prazeres & Medeiros, 2017).…”