Growth and yield responses in wheat and barley to potassium supply under drought or moderately saline conditions in the south-west of Western Australia

Abstract

This study assessed whether more potassium (K) was required for optimal growth and grain yield of cereal crops under drought and salinity than under non-stressed conditions. In 2011, three experiments on wheat (Triticum aestivumL.) with four K rates (0, 20, 40, 80 kg K/ha), four application times (0, 5, 10, 15 weeks after sowing, WAS) and two sources (KCl, K2SO4) were conducted in the central and southern grainbelts of Western Australia. The lack of plant response to K supply at the sites of Bolgart (36 mg K/kg at 0-30 cm) and Borden (25 mg K/kg at 0-30 cm), compared with significant gain in K uptake, dry matter and grain yield at Dowerin (29 mg K/kg at 0-30 cm), was not explained by differences in soil K levels. However, rain fell regularly through the growing season at Bolgart and Borden, whereas a dry spell occurred from stem elongation to grain development at Dowerin. The effectiveness of K application time followed the trend of 0, 5 > 10 > 15 WAS. In 2012, barley (Hordeum vulgare L.) was grown on a moderately saline (saturation extract electrical conductivity ~4 dS/m) and low K (20 mg K/kg) farm in the central grainbelt and treated with 0, 20, 40 and 120 kg K/ha. Applying K increased K uptake but decreased Na uptake, especially at 120 kg K/ha. Plant growth and grain yield increased with K supply, but the difference between the K rates was relatively small, indicating possible partial K substitution by Na. Higher than normal fertiliser K supply on low K soils would enhance the adaptation by cereals to water-limited environments, but K-fertiliser management on moderately saline soils may need to account for both K and Na uptake and use by the crops.

Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review

“…Consequently, low K supply on dry soils may make crops less drought-resistant, which further impairs root growth and K uptake. Our field experiments with wheat grown on low K soils (25-40 mg Colwell K/kg at 0-30 cm) in the central and southern grain belts of WA showed that K treatments (20-80 kg K/ha) enhanced K uptake, dry matter and grain yield (by 0.3-0.6 t/ha) at the drought-affected sites but not at the nonstressed sites (Ma et al 2015;Bell and Ma 2017). The findings suggest that drought stress may increase plant K requirement, and higher than normal fertiliser K supply on low K soils is likely to improve crop adaptation to low rainfall environments.…”

“…Low K decreased the number of spike-bearing tillers per plant in wheat Ma et al 2013) and barley (Andersen et al 1992;Mäkelä et al 2012). In the field, K applied at sowing or up to 5 weeks after sowing was more effective for grain yield in wheat than later application (Ma et al 2015), likely attributed to the beneficial effect of early K supply on tillering. Adequate supply of K to barley also improved straw strength and reduced head loss (C. Li, pers.…”

“…In wheat, most K uptake occurs as the shoot is undergoing its rapid phase of growth (Gregory et al 1979) and minimal K is taken up after anthesis (Rose et al 2007;Ma et al 2013). Shoot K accumulation in wheat during early growth followed by K redistribution during later growth suggests a need for K fertilisation early in the season for wheat, especially on sandy soils with low K buffering (Ma et al 2015). By comparison, soil K availability post flowering can be more important to canola than to wheat (Rose et al 2007).…”

Potassium‐induced decrease in cytosolic Na+ alleviates deleterious effects of salt stress on wheat (Triticum aestivum L.)

“…, Table ) in the shoots and to sugar translocation into the grain through phloem loading and increased photosynthesis (Ma et al . ). Supplemental K + also enhanced grain yield of rice (Bohra & Doerffling ).…”

Optimizing irrigation and fertilization can improve degraded saline soils and increase wheat grain yield

“…The positive effects of the optimal fertilization treatments on the wheat grain yield depended on scientific NPK fertilizer rates for wheat production and on the optimal fertilizer treatments (F312, F321) and more reasonable nutrients distribution of the optimal application treatments (A11, A12) than the conventional treatment (FDU or ADU) (Ma, Bell, Scanlan, Sarre, & Brennan, 2015;Zhan et al, 2016). Additionally, the higher NUE and PUE of the optimal fertilization treatments were due to the higher wheat grain yield and the lesser fertilizer rates than the conventional treatment and the coupling of irrigation with the fertilization (Wang, Chi, Ning, Tian, & Li, 2013).…”