Dry Weight Production and Nitrogen Efficiency Traits in Kentucky Bluegrass Cultivars in Nutrient Solution and Soil

Abstract

Because of the importance of such factors as appeorance and vigor in turf management, genetic selection of Kentucky bluegrass (Poa pratensis L.) is often conducted at high levels of N application. This process can mask potential differences between genotypes in Nelli· ciency, especially under low N levels. The case is also made that because soil is the medium in which plant selections ultimately must perform, cultivar screening for N efficiency in solution culture should relate to results in soil. This study was conducted to evaluate N.utilization efficiency (NUE-mg plant dry matter mg-1 plant N) in six bluegrass cultivars at low (0.2, 0.7 mM N03-N) and high (3.5 mM NOJ-N) levels of N supply in nutrient solution culture (nutrieul· ture) and soil. With high N supply, total plant N accumulation and N.root uptake efficiency (NRE-mg plant N g-l root dry matter) increased iu each cultivar, while NUE and shoot efficiency ratio (SER-mg shoot dry matter mg-1 shoot N) decreased, with the magni· tude and relative response dependent on genotype and medium. As a group, as well os individually, cultivars Asset, Dawn, and Trenton were higher yielding, more responsive to increasing solution N concen· tration, and more ellident (NUE) at low levels of N supply than cultivars Limousine, Barzan, or Midnight. Under low N supply, NUE in nutriculture ranged from 26.2 (g plant dry weight mg-1 N) in Limousine to 40.1 in Asset, and in soil from 63.6 in Midnight to 77.4 in Asset. Differences in NUE among cultivars were more associated with shoot efficiency than with root absorption efficiency. Despite noticeably higher NUE in soil than in nutriculture, and significant effects of N fertility, genotypic differences in the various N efficiency traits in solution culture were also apparent in soil. The results suggest that NUE In Kentucky bluegrass can be enhanced by cultlvar selection under low·N conditions. While the similarities of the actual N conditions between nutriculture and soil remain in question, it appears that solution culture can be used as an effective surrogate for characterizing NUE in divergent types of bluegrass cultivars.

Selection for nitrogen use efficiency and N concentration in timothy

“…Nitrogen use efficiency is usually defined as the DM yield produced per unit of N available in the soil. Studies conducted on annual and perennial species showed that NUE differences are possible through genotype selection (De Datta and Broadbent 1988; Van Loo et al1992;Swiader et al 1994;Bertauski et al 1997).…”

“…Nitrogen use efficiency is usually defined as the DM yield produced per unit of N available in the soil. Studies conducted on annual and perennial species showed that NUE differences are possible through genotype selection (De Datta and Broadbent 1988; Van Loo et al1992;Swiader et al 1994;Bertauski et al 1997).Our overall objective is to improve NUE of timothy by selecting populations or genotypes that will produce greater or similar DM yields with less N fertilizer while maintaining N concentration close to the optimal level required by high-producing ruminant animals. The specific objective of this preliminary study was to classify a wide range of timothy genotypes presenting contrasting characteristics of NUE and N concentration.…”

Physiological and Proteomic Dissection of the Responses of Two Contrasting Wheat Genotypes to Nitrogen Deficiency

“…Overall, the root N absorption efficiency gradually reduced, but the root N utilization efficiency gradually increased in both cultivars, particularly over long-term treatments (Figure 3). The elongation of N stress time and the fact that the roots absorbed and accumulated less N also lead to the increase of N utilization efficiency [37]. Nevertheless, this phenomenon differs in different genotype cultivars, as it was showed that Scout 66 had higher root N absorption efficiency in the roots while Atlas 66 showed higher N utilization efficiency in the roots in response to N deficiency (Figure 3).…”

Nitrate Leaching from Two Kentucky Bluegrass Cultivars as Affected by Nitrate Uptake Capacity and Subsurface Soil Compaction

“…At least two factors are responsible for this efficiency: enhanced uptake capacity in response to N deficiency (Bowman and Paul, 1988;Bowman et al, 1989a) and a very dense root system (Bowman et al, 1989b;Murphy et al, 1994). While most if not all turfgrass species exhibit these two factors, there are differences in N uptake capacity both between species and cultivars (Bertauski et al, 1997;Jiang and Hull, 1998;Liu et al, 1993). We recently reported intraspecific differences among 60 Kentucky bluegrass cultivars in terms of NO 3 uptake rate and further identified cultivars Julia and Midnight as being high and low in NO 3 uptake efficiency, respectively.…”

“…Subsurface soil compaction was included as a second factor. While most if not all turfgrass species exhibit these two factors, there are differences in N uptake capacity both between species and cultivars (Bertauski et al, 1997;Jiang and Hull, 1998;Liu et al, 1993). Each column was filled with Wagram loamy sand with or without a subsurface compaction layer 8.5 cm below the surface.…”