Genetic and Physiological Aspects of Drought Tolerance in Smooth Bromegrass

Abstract

The genetic basis of physiological traits and their association with forage yield and drought tolerance is poorly understood in smooth bromegrass (Bromus inermis Leyss). In this study, half‐sib families from a polycross population were evaluated in the field under normal and water deficit conditions during 2012 and 2013. Water deficit greatly influenced physiological traits and forage production. Under water deficit conditions, most of physiological traits decreased, whereas carotenoid content, proline content, and ratio of chlorophyll a/ chlorophyll b increased. Moderate to high estimates of heritability and genetic variation for yield and physiological traits indicated that selection in this germplasm would be useful in achieving genetic progress. Heritability estimates were slightly decreased for agromorphological traits under water deficit conditions, but the heritability of physiological traits increased in response to water deficit conditions. Significant associations between drought tolerance index and chlorophyll a, chlorophyll b, total chlorophyll content, carotenoids, and proline content showed the importance of these traits to confer drought tolerance in smooth bromegrass. Several genotypes with relatively higher tolerance and forage yield were identified under both moisture regimes that can be used in further breeding programs of smooth bromegrass.

Yield Stability of Contrasting Orchardgrass (Dactylis Glomerata L.) Genotypes Over the Years and Water Regimes 

“…Water deficit caused a significant reduction in all of the measured traits except for DPE and DA in five years of study. As water deficit was applied each year from 1 May onwards, which coincided exactly with the start of flowering and just before pollination, these results were expected and are consistent with the findings of previous studies in orchardgrass (Saeidnia et al 2017;Majidi et al 2016) and smooth bromegrass (Abtahi et al 2019;Saeidnia et al 2020). The region in which the study was conducted (Najafabad, Isfahan, Iran) is a warm and dry area where the summer temperature reaches as high as 45°C and precipitation is null.…”

Root K affinity drivers and photosynthetic characteristics in response to low potassium stress in K high-efficiency vegetable soybean

“…In present study, K high-e ciency vegetable soybean genotypes exhibit greater Chl a/b ratio but lower total Chl content when suffering low K stress. The higher Chl a/b ratio with enhanced relative content of Chl a in response to low K stress might be an adapted mechanism for K high-e ciency genotypes to maintain photosynthetic capacity, because Chl a is the main pigment in leaves that absorbs light energy, which ensures light absorption as much as possible (Abtahi et al, 2019). Similar results were also revealed in the research of Wang et al (2008).…”

“…Consistent with photosynthetic parameters, chlorophyll (Chl) content also re ects the photosynthetic activity in leaves (Szafrańska et al, 2017;Choudhury et al, 2019). The effect of photosynthetic photon ux density on the leaf Chl a/b ratio is one of the most characteristic differences between sun and shade leaves (Abtahi et al, 2019). Typically, total Chl content per unit leaf area is lower and the Chl a/b ratio is greater in sun compared to shade soybean leaves (Anderson, 1986;Fritschi et al, 2007).…”

Root K Affinity Drivers and Photosynthetic Characteristics in Response to Low Potassium Stress in K High-Efficiency Vegetable Soybean

“…In the present study, K high-efficiency vegetable soybean genotypes exhibit lower total Chl content but greater Chl a/b ratio when suffering low K stress. The effect of photosynthetic photon flux density on the leaf Chl a/b ratio is one of the most characteristic differences between sun and shade leaves ( Abtahi et al, 2019 ). Typically, total Chl content per unit leaf area is lower and the Chl a/b ratio is greater in sun compared with shade soybean leaves ( Anderson, 1986 ; Fritschi and Ray, 2007 ).…”

“…Typically, total Chl content per unit leaf area is lower and the Chl a/b ratio is greater in sun compared with shade soybean leaves ( Anderson, 1986 ; Fritschi and Ray, 2007 ). The higher Chl a/b ratio with enhanced relative content of Chl a in response to low K stress might be an adapted mechanism for K high-efficiency genotypes to maintain photosynthetic capacity because Chl a is the main pigment in leaves that absorbs light energy, which ensures light absorption as much as possible ( Abtahi et al, 2019 ). Similar results were also revealed in the research of Wang et al (2008) .…”