Genotypic Variation of the Ability of Root to Penetrate Hard Soil Layers among Japanese Wheat Cultivars

Relationship between Deep Root Distribution and Root Penetration Capacity Estimated by Pot Experiments with a Paraffin and Vaseline Layer for Landraces and Recent Cultivars of Wheat

“…Ethiopian landraces 'Et-23 A-1-97 (Et-23)', 'Et-31 A-1-113 (Et-31) ', had a high RP and CIMMYT cultivars 'Plover'S' (Plover)', 'Snipa'S' (Snipa)' and 'Bittern'S' (Bittern)' had low RP, respectively, in the pot experiments (Kubo et al, 2004(Kubo et al, , 2006. 'Haruyutaka' is a major cultivar in Hokkaido, Japan, bred at the Hokkaido Prefectural Agricultural Experiment Station in Kitami in 1985 and has a low RP (Kubo et al, 2006). Five or six genotypes of these seven genotypes were used in root box and fi eld experiments.…”

“…The structure of pot, growth conditions of seedlings and experimental design were the same as those used by Kubo et al (2006). Briefly, the pot consisted of a 10-cm tall cylinder placed on a 5-cm tall cylinder.…”

“…An experimental method to estimate the penetrating capacity of roots (RP) using pots having a layer made from a mixture of paraffin and Vaseline (PV layer) has been developed for rice (Yu et al, 1995), cotton (Klueva et al, 2000) and wheat (Botwright-Acuna and Wade, 2005;Kubo et al, 2004Kubo et al, , 2005Kubo et al, , 2006, and the genotypes of these crops with high RP have been identifi ed. The success of this experimental method is depends on identifying genotypes with a higher ability of deep rooting in the fields (Clark et al, 2002), but such information is lacking in wheat.…”

“…The number of roots penetrating through a PV layer for each plant (NRP) evaluated by the pot experiment was compared with the number of roots on the vertical surface (root frequency (RF): root number cm -2 soil surface) in a root box and fi elds using three Ethiopian landraces with high RP and three recent cultivars bred by International Maize and Wheat Improvement Center (CIMMYT) of spring durum wheat (Triticum turgidum L. var. durum), and one Japanese cultivar of spring bread wheat (T. aestivum L.), evaluated in previous studies by Kubo et al (2004Kubo et al ( , 2006.…”

Structure and Function of the Root Cap

“…Under such an environment, root penetration into the hard pan layer (Kubo et al, 2006) allows crop roots to grow into deeper soil layer, which often alleviates the crop yield reduction due to the physical stresses. The deep rooting is mainly determined by the direction of root growth (rooting angle) and root elongation rate.…”