Physiological responses of selected African sorghum landraces to progressive water stress and re-watering

Abstract

Sorghum is particularly drought tolerant compared with other cereal crops and is favoured for subsistence farming in water scarce regions of the world. This study was conducted to identify South African sorghum landraces with superior drought tolerance compared with a drought tolerant breeding line (P898012). Seedlings of 14 South African sorghum landrace accessions were initially screened for drought tolerance by assessing percentage leaf water content (LWC) during progressive water deficit. Four landraces (designated LR5, LR6, LR35 and LR36) recorded higher LWC than P898012.These were subsequently evaluated with P898012 during the reproductive growth stage, for their physiological responses to mild (four days) and severe (six days) water stress treatments and a moderate re-watered treatment on day seven. Plant height, soil moisture and LWC were measured during harvests. Chlorophyll, carotenoid and proline contents were quantified. All five genotypes maintained LWC above 80% during mild and severe stress treatments. For LR35 and LR36, LWC were recorded within 8% less in comparison to their well-watered controls following the moderate re-watered treatment.Significantly higher chlorophyll and carotenoid contents were recorded for both LR6 and LR35 in comparison to P898012 during severe stress. When LWC was reduced in LR36 (to 73.68%) and LR35 (to 73.51%), their proline content significantly increased by 14-and 16-fold, respectively. In this study, we have identified four previously uncharacterised sorghum genotypes exhibiting drought tolerance and described their physiological responses during water deficit and moderate re-watering. Aside from their application to breeding, these landraces are valuable resources to elucidate genetic mechanisms that enable drought tolerance in South African sorghum.3

Improvement of growth performance of Amorpha fruticosa under contrasting regime of water and fertilizer in coal-contaminated spoils using response surface methodology

“…1de; Additional file 1: Figure S1; Table 1). These findings indicated that due to scarcity of soil-water, nutrients present in the soil did not mobilize well, and plant roots could not uptake it adequately, which ultimately prevented water and nutrients flow through the xylem to the surrounding cells, as observed in other plant species under watershortage conditions [19][20][21]. Thus, the deficiency of nutrients and water eventually led to the inhibition of cell growth and elongation [21], as was also manifested in this study in terms of plant height and stem diameter (Table 1).…”

Comparative physiological and root proteome analyses of two sorghum varieties responding to water limitation

“…Furthermore, drought tolerant/resistant sorghum varieties are highly water use efficient (WUE) with an extensive root system for water absorption 23 and a thick waxy cuticle that retards excessive water loss 17 . Different sorghum varieties also accumulate varying amounts of osmolytes 24 – 26 for osmotic adjustment during periods of drought stress.…”

“…The sorghum genome has been sequenced 28 and is part of the growing cereal genomics resource 27 , 29 , guiding crop breeding strategies. Sorghum physiological 26 , 30 , 31 , transcriptomic 32 , 33 , and proteomic 34 – 37 responses to osmotic/drought stress together with computational characterization of candidate genes 38 , 39 have been conducted. However, more comparative studies are required in order to fully understand how sorghum survives in hot and dry environments that are unsuitable for most crops.…”

Sorghum mutation breeding for tolerance to water deficit under climate change

“…Plant leaf senescence is considered as a post-flowering drought stress symptom (Burke et al, 2013). Green plants such as sorghum have two options for maintaining a high tissue water status during periods of soil moisture deficit, either by decreasing water loss due to transpiration or by increasing water uptake (Devnarain et al, 2016). Leaf senescence reduces seriously the source-sink translocation from leaves to grain (Krupa et al, 2017).…”