Germination Responses of Ryegrass (Annual vs. Perennial) Seed to the Interactive Effects of Temperature and Salt-Alkali Stress

Abstract

Ryegrass is considered a useful grass species for forage production and turf purposes. Annual ryegrass (Lolium multiflorum Lam.) and perennial ryegrass (Lolium perenne L.)are two species of ryegrass with similar genomes. So far, little information exists concerning their physiological response to salt-alkali stress during germination stage, especially under different temperature regimes. Seeds of ryegrass were germinated at four alternating temperatures (10–20, 15–25, 20–30, and 25–35°C) with salinity (NaCl) and alkalinity (Na2CO3, high pH) stresses. Results showed that optimal germination for both species under stress conditions occurred at higher temperatures (20–30°C for annual ryegrass; 20–30°C and 25–35°C for perennial ryegrass). Germination percentage and germination rate were both inhibited by increasing salinity or alkalinity, particularly higher alkalinities under any temperature. The inhibitory effects of the high salinity on germination were greater at 10–20°C for both species. However, seeds were subjected to more stress at 25–35°C under alkali stress even though the concentration was very low. In addition, both high and low temperatures lead to a markedly decrease in seed germination under alkali stress for perennial ryegrass. Recovery percentage of both species were highest at 400 mM salinity and 25 mM alkalinity under any temperature, especially 10–20°C, and 25–35°C also resulted in lower recovery percentages under both stresses for ryegrass. Moreover, annual ryegrass had a much higher recovery percentage than perennial ryegrass under such stress conditions. These results suggest that salinity stress and alkalinity stress are greatly different, and the salt-alkaline tolerance of ryegrass seeds is greatly affected by the interactions of temperature and salinity–alkalinity.

Trichoderma harzianum IS005-12 promotes germination, seedling growth and seedborne fungi suppression in Italian ryegrass forage

“…of mature IRG seeds can be also diminished by different environmental factors (Lin et al 2018) as well as seed pathogens, enhancement of germination and growth of mature seeds is desirable too.…”

Effect of a Micronutrient Fertilizer and Fungicide on the Germination of Perennial Ryegrass Seeds (Lolium perenne L.) in Field Conditions

“…Previous studies have mainly dealt with the effect of the temperature, length of the day, and salinity level on the germination of perennial ryegrass seeds [40]. Alkaline stress [41], the presence of seminal fungi, and the correlation between the basic physical properties of the seeds, with their diameter, shape factor, spherical index, and density [42], have also been studied. It can therefore be noted that in recent years a number of studies have been undertaken to determine the key factors affecting perennial ryegrass germination, given the importance of its seed production in many regions of the world.…”

Physiological and Proteomic Analyses Reveal Adaptive Mechanisms of Ryegrass (Annual vs. Perennial) Seedlings to Salt Stress

“…ETR = Φ PSII × PPFD × 0.5 × 0.84 (3) where PPFD was the actinic light intensity, 0.5 was the proportion of light energy assigned to PS II, and 0.84 meant that 84% of the incident light was absorbed by seedlings [29]. All the treatments have three replicates.…”

“…These two species have very similar genomes but have great differences in morphological characteristics and uses. For example, annual ryegrass can be grown together with other grass species to improve pasture quality [2,3]. Perennial ryegrass is also valued for high yield potential as forage grass, but this species can also be used for a variety of turf applications (e.g., home lawns, fairways, athletic fields, and golf courses) [4,5].…”