Drought Effect on Grain Number and Grain Weight at Spike and Spikelet Level in Six-Row Spring Barley

Abstract

Water is the primary regulator of yield formation in cereals. The effect of water limitation and its timing on development of yield components were studied in detail at spike and spikelet level in spring barley (Hordeum vulgare L.). An experiment with three watering treatments (control watering, CONT; drought prior to pollination, DR1 and terminal drought, DR2) was set up in a large greenhouse (20 × 30 m). In addition to watering treatments, two NPK fertilizer application rates (0 and 120 kg N ha−1) were used to investigate the fertilizer effect. The drought effect exceeded the effect of fertilizer application for grain number and single grain weight (SGW). DR1 reduced the number of grains, whereas DR2 reduced both SGW and the number of grains. Resuming the watering at pollination (DR1) restored photosynthesis and enhanced grain filling, resulting in almost similar SGW in DR1 and CONT plants. Spikelets in the upper mid‐section of the spike dominated yield formation in all treatments. This was particularly emphasised in DR1 plants as 58 % of the grain yield was produced in spikelets 3–5, whereas in DR2 and CONT plants it was 39 % and 36 %, respectively. Hence, drought prior pollination strongly reduced yielding capacity (=grain number) in apical and basal spikelets. DR1 and DR2 reduced substantially grain yield and grain N yield resulting in low nitrogen use efficiency.

Impact of Pre-Anthesis Water Deficit on Yield and Yield Components in Barley (Hordeum vulgare L.) Plants Grown under Controlled Conditions

“…Indeed, the current study confirmed this by the presence of variation amongst the studied 11 barley genotypes. The effects of water stress on the yield reduction of barley have been well documented [28,29].The present study showed that yield and yield components were significantly reduced in all tested genotypes due to water deficit during tillering and stem elongation stages (e.g., yield reduced by 66% and 54% at SS and SE, respectively; Table 4). These results indicated that drought stress during the pre-anthesis period reduced grain yield by decreasing the number of fertile spikes and grains per plant (Table 4).…”

Physiological and Biochemical Responses to Heat Stress on Barley Seedlings and Their Impact on Growth and Yield

“…Toth et al (2005) attributed the reduction in photosynthetic pigments to abrupt damage of the PSII units, loss of their capacity of oxygen evolution leading to a restricted electron transport and thus reduced rate of photosynthesis. The reduced rate in photosynthesis may have contributed to the reduction in plant height, number of tiller, fresh weight and dry weight since the production of biomass is the result of photosynthesis (Rajala et al, 2011).…”

Irrigation of Field Crops in the Boreal Region

“…At that stage, the limited availability of water and assimilates affects the translocation processes, from sources to sinks, filling grains. In oat, however, water deficit at post-anthesis mainly decreased the number of grains (Peltonen-Sainio & Mäkelä, 1995), similarly to wheat (Rajala et al, 2011), probably due to limited source capacity. Fábián et al (2011) showed that water deficit occurring after pollination, during early grain development stage, decreases the embryo size and increases the degradation of cell layers surrounding the ovule.…”

“…For spring cereals, long coleoptiles and vigorous seedling emergence are important traits in Boreal conditions, where there is uneven precipitation and a short growing season (reviewed in Mäkelä et al, 2008). In spring barley (Hordeum vulgare L.), early season water deficit reduced both the sink and source capacity of plants through decrease in photosynthesis and thereby dry weight accumulation and number of grains (Rajala et al, 2011). According to Jamieson et al (1995), a water deficit related decrease in dry weight accumulation of barley during the early phases of growth is mainly due to reduced radiation use efficiency, which does not recover completely after stress relief.…”

“…After anthesis, water deficit mainly caused decreases in grain yield and fewer grains in barley (Rajala et al, 2011). At that stage, the limited availability of water and assimilates affects the translocation processes, from sources to sinks, filling grains.…”