Search Results

You are looking at 1 - 10 of 162 items for :

  • "nitrogen-use efficiency" x
  • Refine by Access: All x
Clear All
Free access

Giuseppe Colla, Carolina María Cardona Suárez, Mariateresa Cardarelli, and Youssef Rouphael

selection and use of genotypes that have high nitrogen use efficiency (NUE) could lead to a low environmental impact in agroecosystems while allowing high yields to be maintained ( Lynch, 1998 ). Nitrogen use efficiency is defined as the yield of harvestable

Free access

Jeremy R. Pinto, Rhiannon A. Chandler, and R. Kasten Dumroese

concentration was determined by MDS Harris Laboratories (Lincoln, NE) using Kjedahl digestion. Nitrogen use efficiency was calculated by dividing the nutrient content of the entire seedling by the total amount of N applied to the seedling. Nitrogen concentration

Free access

Pascal Nzokou and Bert M. Cregg

. Assimilatory nitrogen use efficiency (ANUE), and N use efficiency generally increased with irrigation amounts ( Table 3 ). The index of N availability per unit foliage (N/RW) was the lowest at the highest irrigation treatment and highest at the lowest treatment

Free access

Dan Drost, Rich Koenig, and Terry Tindall

Nitrogen (N) losses can be substantial in furrow-irrigated onions (Allium cepa L.). Polymer-coated urea (PU) may reduce N losses and result in an increase in productivity. In this study, we investigated the effects of different rates and blends of urea and PU on onion yield and N use for two cropping seasons. Nitrogen was applied at 112, 168, and 224 kg·ha-1 as PU or urea. In addition, three PU/urea blends equal to 224 kg·ha-1 of N were compared. Plant growth and N concentration, soil nitrate concentrations, and bulb yield were evaluated each year. Onion yield decreased by 95 Mg·ha-1 for each 25% increase in the proportion of urea in the fertilizer blends. Reducing the N rates from 224 to 112 kg·ha-1 had minimal effect on bulb yield when all the fertilizer was supplied by urea. A reduction of N applied from 224 to 168 kg·ha-1 had little effect on yield, although a further reduction to 112 kg·ha-1 did significantly reduce bulb yield when the entire N was supplied from PU. Nitrogen source and rate had no effect on bulb maturity and only minor effects on leaf area and storage potential. Soil sampling indicated that more N was retained in PU-treated onion beds than in urea-treated beds, which improved nitrogen use efficiency. In addition, N use efficiency improved when there was more PU in the blend and when PU was compared with urea at the same rate. We conclude that the use of PU can dramatically improve N use efficiency and productivity in direct-seeded onions.

Free access

Desire Djidonou, Xin Zhao, Eric H. Simonne, Karen E. Koch, and John E. Erickson

with the grafting process. Yield, irrigation water use efficiency, and nitrogen use efficiency. Mature green tomato fruit and fruit at more advanced ripening stages were harvested from 10 plants in each treatment combination per replication. Fruit were

Free access

Juan Carlos Melgar, Arnold W. Schumann, and James P. Syvertsen

, NJ Sorgona, A. Abenavoli, M.R. Gringeri, P.G. Cacco, G. 2006 A comparison of nitrogen use efficiency definitions in Citrus rootstocks Sci. Hort. 109 389 393 Sultan, S

Free access

Anita Gunnarsson, Börje Lindén, and Ulla Gertsson

BG system). The net effect is difficult to forecast. Ratio of net inorganic nitrogen equivalents to Sum of all N in ley and red beet foliage (nitrogen use efficiency). The ratio of net inorganic N equivalents to the Sum of all N in ley and red beet

Full access

Paolo Benincasa, Marcello Guiducci, and Francesco Tei

Meaning of nitrogen use efficiency. Several studies have addressed the optimization of fertilization and the improvement of NUE of crops to achieve high yields with reduced N fertilization rates and limited environmental side effects related to N

Free access

Kenneth V. Pecota and Wanda W. Collins

Eight clones of sweetpotato [Ipomaea batatas (L.) Lam.] at five N levels in 1992 and five clones at three N levels in 1993 were evaluated for genotypic variation in N use efficiency [NUE (yield/unit N fertilizer applied)], uptake efficiency (N accumulated/unit N fertilizer applied), and utilization efficiency (yield/N accumulated). There were significant genotypic differences for all NUE components and the variables used for calculation. When total marketable yield was used in calculating NUE, utilization efficiency was always more important than uptake efficiency in accounting for NUE variation. Regression equations developed from 1992 NUE components and selected non-N variables used to calculate them ranked the 1993 NUE components correctly when averaged over all clones. Uptake efficiency could be predicted by biomass; utilization efficiency by total marketable yield.

Free access

Zhongchun Jiang, W. Michael Sullivan, and Richard J. Hull

Efficient utilization of fertilizer-nitrogen (N) by turfgrasses is probably related to N uptake efficiency of roots and metabolic efficiency of absorbed N in roots and shoots. This study evaluated Kentucky bluegrass (Poa pratensis L.) cultivars for potential differences in nitrate uptake rate (NUR), temporal variation in NUR, and the relationship between NUR and N use efficiency (NUE), defined as grams dry matter per gram N. Six cultivars were propagated from tillers of seeded plants, grown in silica sand, mowed weekly, and watered daily with a complete nutrient solution containing 1.0 mm nitrate. A nutrient depletion method from an initial nitrate concentration of 0.5 mm was used to determine NUR of 5-month-old plants. NUR (μmol·h-1 per plant) of the six cultivars ranked as follows: `Blacksburg' > `Conni' > `Dawn' > `Eclipse' = `Barzan' > `Gnome'. When NUR was based on root weight, `Conni' ranked highest; when NUR was based on root length, surface, or volume, `Eclipse' ranked highest. Averaged across cultivars, NUR on the second day was greater than NUR for the first day of nitrate exposure. Temporal variation was greatest in `Blacksburg', while none was noted in `Conni' or `Eclipse'. Cultivar differences in NUE were significant in fibrous roots, rhizomes, and leaf sheaths, but not in leaf blades and thatch. Total nitrate uptake was positively related to total N recovered and total plant dry matter, but NUR based on root weight was negatively correlated with NUE of the whole plant.