The impact of limited soil moisture and waterlogging stress conditions on morphological and anatomical root traits in maize (Zea mays L.) hybrids of different drought tolerance

Abstract

Key words: m a i z e , d r o u g h t , w a t e r l o g g i n g , stress t o l e r a n c e , root m o r p h o l o g y , r o o t a n a t o m y Abstract Effects of soil drought or waterlogging on the morphological traits of the root system and internal root anatomy were studied in maize hybrids of different drought tolerance. The investigations comprised quantitative and qualitative am~lyses of a developed plant root system through determining the nnmber, length and dry matter of the particular components of the root system and some traits of the anatomical structure of the semihal root. Obtained results have demonstrated a relatively broad variation in the habit of the root system. This mainly refers, to the number, length and dry matter of lateral roots, developed by seminal root, seminal adventitious and nodal roots as well as to some anatomical properties of the stele, cortex and metaxylem elements.Plants grown under waterlogging or drought conditions showed a smaller number and less dry matter of lateral branching than plants grown in control conditions. The harmful effect of waterlogging conditions on the growth of roots was greater when compared with that of plants exposed to drought. In the measurements of the root morphological traits, the effect of soil drought on the internal root anatomical characteristic was weaker than the effect of soil waterlogging. The observed effects of both treatments were more distinct in a drought sensitive hybrid Pioneer D than in drought resistant Pioneer C one. The drought resistant hybrid Pioneer C distinguished by a more extensive rooting and by smaller alterations in the root roof phology caused by the stress conditions than drought sensitive hybrid Pioneer D one. Also the differences between the resistant and the sensitive maize hybrids were apparent for examined root anatomical traits. Results confirm that the hybrid Pioneer D of a high drought susceptibility was found to be also more sensitive to periodical soil water excess. A more efficient water use and a lower shoot to root (S:R) ratio were found to be major reasons lbr a higher stress resistance of the hybrid Pioneer C.The reasons/'or a different response of the examined hybrids to the conditions of drought or waterloggiug may be a more economical water balance and more favourable relations between the shoot and root dimensions in the drought resistanl geno--type. The observed modifications of the internal root structure caused by water deficit in plant tissues may partly influence on water conductivity and transport within roots.The results suggest that the morphological and anatomical traits of the maize root system may be used in practice as direct or indirect selection criteria in maize breeding.

Hydraulic regulation strategies for whole-plant water balance of two maize inbred lines differing in drought resistance under short-term osmotic stress

“…First, the 478 plants had larger ratios of root surface area/leaf area than the Tian4 plants (Fig. 1), a result that had also been observed in drought-resistant maize hybrids (Grzesiak et al 1999). Second, the K root of 478 was higher than that of Tian4 at noon (Fig.…”

Interspecific differences in root architecture among maize and triticale genotypes grown under drought, waterlogging and soil compaction

“…The heavy suppression of lateral root growth would affect plant nutrition and water relation because the soil compaction resulted in decreased size of root system, increased irregularity of root distribution and thus in greater distances for the transport of water and nutrients to the nearest roots (Tardieu 1991;Lipiec et al 1996). Also the restriction in number and length of each root type in conditions of high soil impedance accompanied by a decrease in leaf water potential, decrease in photosynthesis, and changes in stomata conductance and contents of internal carbon dioxide (Grzesiak et al 1999). Highlighting the water relation and gas exchange rate of plants under soil stresses, many studies indicate that leaf water status and gas exchange parameters Fig.…”

“…These morphological differences are usually closely connected with the physiological functions of the particular components of the root system. Root system structure may be characterized by the number, length, diameter of the particular root components, direction of extension of nodal roots and branching (rooting angle between plant axis and root) (Kono et al 1987a, b;Yamauchi 1993;Grzesiak et al 1999). The particular components of the plant root system show both similarities and differences in their functions.…”

“…Other type designated as a ''scattered'' develops fewer but longer nodal roots, many of which runs obliquely in the soil profile (larger rooting angle). Although it is reported that the responses of growth in each root type and architecture of root system to soil environmental stresses are different among plants with concentrated and scattered root system (Kono et al 1987b;Yamauchi 1993;Iijima et al1991;Chan and Weil 2010;Grzesiak et al 1999Grzesiak et al , 2013. Typical responses of a plant root system structure to soil water content, temperature, soil compaction, pH is reduction in number, length of roots and restriction of downward penetration of the main root axes.…”

“…Those changes accompanied by morphological changes in shoot include a decrease in plant height, leaf number, area and their thickness and changes in the shoot-to-root ratio dry mass and a decrease in grain yield (Clark et al 2003;Fageria et al 2006). Inhibited plant growth is mostly attributed to reduced rooting volume Yamauchi 1993;Grzesiak et al 1999Grzesiak et al , 2002Masle 2002;Fageria et al 2006). …”