The Effect of Late‐terminal Drought Stress on Yield Components of Four Barley Cultivars

Abstract

Barley (Hordeum vulgare L.) is an important winter cereal crop grown in the semiarid Mediterranean, where late‐terminal drought stress during grain filling has recently become more common. The objectives of this study were to investigate the growth performance and grain yield of four barley cultivars under late‐terminal drought stress under both glasshouse and field conditions. At grain filling, four barley cultivars (Rum, ACSAD176, Athroh and Yarmouk) were exposed to three watering treatments: (1) well‐watered [soil maintained at 75 % field capacity (FC)], (2) mild drought stress at 50 % FC, (3) severe drought stress at 25 % FC in the glasshouse experiment and (1) well‐watered (irrigated once a week), (2) mild drought (irrigated once every 2 weeks), (3) severe drought (non‐irrigated; rainfed) in the field. As drought stress severity increased, gross photosynthetic rate, water potential, plant height, grain filling duration, spike number per plant, grain number per spike, 1000‐grain weight, straw yield, grain yield and harvest index decreased. In the glasshouse experiment, the six‐row barley cultivars (Rum, ACSAD176, and Athroh) had higher grain yield than the two‐row barley cultivar (Yarmouk), but the difference was not significant among the six‐row cultivars under all treatments. In the field experiment, Rum had the highest grain yield among all cultivars under the mild drought stress treatment. The two‐row cultivar (Yarmouk) had the lowest grain yield. In general, the traditional cultivar Rum had either similar or higher grain yield than the other three cultivars under all treatments. However, the yield response to drought differed between the cultivars. Those, Rum and ACSAD176, that were capable of maintaining a higher proportion of their spikes and grains per spike during drought also maintained a higher proportion of their yield compared with those in well‐watered treatment. In conclusion, cultivar differences in grain yield were related to spike number per plant and grain number per spike, but not days to heading or grain filling duration.

Gene expression and activity of antioxidant enzymes in barley (Hordeum vulgareL.) under controlled severe drought

“…But the decrease in Rum was lower than that in Yamrouk. Hence, Rum is drought-tolerant whileYarmouk is drought-sensitive (Samarah et al 2009). A significant and similar decrease in growth and photosynthetic activity of the two genotypes was shown when exposed to controlled severe drought at the vegetative stage (Harb & Samarah 2015).…”

“…This suggests that at the molecular level, there are specific drought responses to each genotype. Indeed, Yarmouk genotype was shown to be more droughtsensitive when drought started at the flowering stage than when started at the vegetative stage (Samarah et al 2009;Haddadin et al 2013). Hence, in drought imposed at the vegetative stage different molecular and biochemical responses in the two genotypes result in the same physiological and morphological responses.…”

Bioprospecting Drought Tolerant <i>Trichoderma harzianum</i> Isolates Promote Growth and Delay the Onset of Drought Responses in Wheat (<i>Triticum aestivum</i> L.)

“…Many studies have shown the decreased photosynthetic activity under drought stress due to stomatal or non-stomatal mechanisms (Del Blanco et al, 2000;Samarah et al, 2009). Under drought, the maintenance of leaf turgor may also be achieved by way of osmotic adjustment in response to the accumulation of proline, sucrose, soluble carbohydrates, glycine betaine, and other solutes in cytoplasm thereby improving water uptake from drying soil.…”

Alfalfa and Its Symbiosis Responses to Osmotic Stress

“…The reduction of stomatal conductance (g s ) and stomatal density is among the remarkable responses to water deicit in alfalfa plants [23,24]. As a consequence of the stomata closure, the difusion of CO 2 from the atmosphere to the carboxylation site is reduced, which inluences the activity of RuBisCO as well as other enzymes such as sucrose phosphate synthase (SPS) and nitrate reductase (NRA), whose inhibition is often considered to be the main cause of the decrease of water-deicient photosynthesis [25]. It has been shown that decreasing water content and ion concentration in water-deicient leaves are more limiting for photosynthesis than closure of stomata [26].…”