Root growth and nitrate utilization of maize cultivars under field conditions

Abstract

In a 2-year field study conducted on a high fertilized Gleyic Luvisol in Stuttgart-Hohenheim significant differences among 10 maize cultivars were observed in soil nitrate depletion. The different capability of the cultivars to utilize nitrate particularly from the subsoil was positively correlated with (a) shoot N uptake at maturity, and (b) root length density (Lv) in the subsoil layers at silking. "Critical root length densities" for nitrate uptake were estimated by (a) calculating uptake rates per unit root length (U), (b) subsequent calculation of needed nitrate concentration in soil solution (Cl) to sustain calculated U according to the Baldwin formula, and (c) reducing measured Lv and proportionate increase of U until needed concentration equaled measured concentration. Uptake rate generally increased with soil depth. "Critical root length densities" for cultivar Brummi (high measured root length densities and soil nitrate depletion) at 60-90 cm depth ranged from 7 % (generative growth) to 28 % (vegetative growth) of measured Lv Measured root length density of each other cultivar was higher than "critical root length density" for Brummi indicating that the root system of each cultivar examined would have been able to ensure N uptake of Brummi. Positive relationships between root length density and nitrate utilization as indicated by correlation analysis therefore could not be explained by model calculations. This might be due to simplifying assumptions made in the model, which are in contrast to non-ideal uptake conditions in the field, namely irregular distribution of roots and nitrate in the soil, limited root/soil contact, and differences between root zones in uptake activity. It is concluded from the field experiment that growing of cultivars selected for high N uptake-capacity of the shoots combined with "high" root length densities in the subsoil may improve the utilization of a high soil nitrate supply.

Influence of root zone nitrogen management and a summer catch crop on cucumber yield and soil mineral nitrogen dynamics in intensive production systems

“…Kristensen and Thorup-Kristensen (2004a) reported that soil N depletion by catch crop species was highly correlated with their rooting depth but there was little correlation with root density. According to Wiesler and Horst (1994), sweet corn roots may penetrate the soil to a depth of 1.5 m. However, Kristensen and Thorup-Kristensen (2004b) observed shallow rooting (0.3 m) by sweet corn in minirhizotrons and they attributed the differences in their results to relatively low temperatures in spring and summer. In our experiment sweet corn rooting depth approached 1.1 m, which was in accordance with the results of Ren (2003) at Dongbeiwang in the Beijing suburbs.…”

Nitrogen use efficiency in rapeseed. A review

“…As root growth and maintenance are energetically costly, root architecture is a lever to optimize the balance between nitrogen absorption ability and metabolic cost (Lynch 2014). From this perspective, increasing the root surface by increasing fine root density has been considered as one possible strategy in other crops (White et al 2013) such as maize (Wiesler and Horst 1994), faba beans (Kage 1997), and Kentucky bluegrass (Sullivan et al 2000).…”

Effects of elevated atmospheric CO2and soil water availability on root biomass, root length, and N, P and K uptake by wheat

“…Within the 'dry' treatment, plants might have acquired more N at elevated [COg] either because the soil remained wetter between waterings, or because of their greater root length density (e.g. Wiesler & Horst 1994), or both. This N was taken up from the top soil layers, which might reflect the extra stimulation of root growth in the top soil layers by elevated [CO2].…”