Rooting depth and water use efficiency of tropical maize inbred lines, differing in drought tolerance

Abstract

Deep rooting has been identified as strategy for desiccation avoidance in natural vegetation as well as in crops like rice and sorghum. The objectives of this study were to determine root morphology and water uptake of four inbred lines of tropical maize (Zea mays L.) differing in their adaptation to drought. The specific questions were i) if drought tolerance was related to the vertical distribution of the roots, ii) whether root distribution was adaptive or constitutive, and iii) whether it affected water extraction, water status, and water use efficiency (WUE) of the plant. In the main experiment, seedlings were grown to the V5 stage in growth columns (0.80 m high) under well-watered (WW) and water-stressed (WS) conditions. The depth above which 95 % of all roots were located (D 95 ) was used to estimate rooting depth. It was generally greater for CML444 and Ac7729/ TZSRW (P2) compared to SC-Malawi and Ac7643 (P1). The latter had more lateral roots, mainly in the upper part of the soil column. The increase in D 95 was accompanied by increases in transpiration, shoot dry weight, stomatal conductance and relative water content without adverse effects on the WUE. Differences in the morphology were confirmed in the V8 stage in large boxes: CML444 with thicker (0.14 mm) and longer (0.32 m) crown roots compared to SCMalawi. Deep rooting, drought sensitive P2 showed markedly reduced WUE, likely due to an inefficient photosynthesis. The data suggest that a combination of high WUE and sufficient water acquisition by a deep root system can increase drought tolerance.

Stay-green quantitative trait loci's effects on water extraction, transpiration efficiency and seed yield depend on recipient parent background

“…It has also been shown in rice that stay-green lines have a higher profusion of roots under water stress, leading to higher stay-green scores (Hoang et al, 2009). Similar work testing the relation between roots and drought tolerance has been done in maize (Hund et al, 2009;Landi et al, 2007).…”

Corn root morphoanatomy at different development stages and yield under water stress

“…Lavinsky et al (2015) studied the DKB 390 hybrid under drought imposed only at the flowering stage and reported no changes in the length of fine roots. However, Hund et al (2009) concluded that the tolerant genotype, CML44, presents greater length of fine roots at the V5 growth stage.…”

Water: the most important ‘molecular’ component of water stress tolerance research

“…Zaman-Allah and colleagues (2011a) reached the same conclusion with twenty chickpea genotypes contrasting for terminal water stress tolerance. Nevertheless, the benefit of deeper root systems has been shown in other studies (Kirkegaard et al 2007;Christopher et al 2008;Hund et al 2009). For example, a simulation study indicated that maize yields would increase if the root depth increased (Sinclair and Muchow 2001).…”