Fertilization, Nutrient Composition, and Yield Relationships in Irrigated Spring Wheat¹

Abstract

Wheat acreage in Arizona has increased tenfold since the introduction of high yielding semidwarf spring wheats (Triticum aestivum L.). Because of the higher yield potential of these wheat cultivars, many growers have applied more fertilizer without evidence that these semidwarf spring wheats require more nutrients. This study was initiated to evaluate the effect of N and P fertilization on the growth and yield of semidwarf spring wheat and to develop a workable tissue test to determine the nutritional status of the wheat plan. Tissue samples for chemical analysis were taken from uheat plants in three different field experiments. These experiments consisted of 1) six rates of N and three rates of P, 2) six rates of N and six wheat cultivars, and 3) six rates of N and three wheat cultivars. The NO3‐N concentration in the lower 5 to 8 cm of the stem indicated the N status of the wheat plant. Minimum levels of NO3‐N for different stages of growth were established for Southwestern Arizona conditions. In two experiments excessive N decreased yields slightly when compared to sufficient levels of N. The main effects of N on grain yield components were to increase the number of heads/unit area, increase the number of seeds/ head, and decrease the weight of individual seeds. The total N content in the grain increased with increased N applications. Determination of P in the lower portion of wheat stems was not found to be suitable for indicating the P status of the crop.

Plant part selection and evaluation of factors affecting analysis and recovery of nitrate in irrigated durum wheat tissue

“…This expectation was verified in this study and strongly indicates that analysis of leaf or wholeplant samples for N0 3 -N would be a much less sensitive indicator of Downloaded by [University of Calgary] at 03:32 03 February 2015Ν nutritional status of wheat compared to N0 3 -N analysis of basal stem tissue. Partitioning data for N0 3 -N confirm the recommended wheat stem sampling guidelines of Gardner and Jackson(2).…”

“…Because nitrogen (N) is the nutrient most often limiting irrigated small grain production, several attempts have been made to characterize the Ν status of these crops using tissue tests for NO3-N (2,3,4,5,6,7,8,9,10). These tests have proven to be reliable indicators of Ν nutrition of small grains in Australia and Cyprus (4,5,6) as well as in Arizona, (3,4,7) but they have been inconsistent or impractical in other locations (8,9 ).…”

Diagnosing nitrogen fertilization requirements of cereals in less than 30 seconds

“…The last is not easily amenable to prediction, so the decision to fertilize without reference to future weather conditions is a risk which it is impossible to avoid. The need of plants for Ν can be decided by plant analysis for NO3-N concentration [1,2,4,5], since plant composition is an integration of seasonal and site effects [13]. The decision has to be reached quickly and cannot be delayed by sending samples away for laboratory analysis.…”

The effect of rhizoctonia root disease and applied nitrogen on growth, nitrogen uptake and nutrient concentrations in spring wheat

“…However, extreme nitrogen deficiency was not attained in their trials, and all the BS[NO3-N ] levels they report are above 1000 mg kg 1. The is also used as a predictive test to forecast nitrogen limitation to grain yield of the crop (Gardner and Jackson, 1976;Papastylianou et al 1984). Predictive criteria for BS[NO3-N ] developed from field trials are understandably higher than diagnostic criteria, and have been defined as 6000 to 10,000mgkg -1 at joining in Arizona, USA (Gardner and Jackson, 1976), and in South Australia as 6000 to 10000 mg kg -1 at tillering (Papastylianou et al, 1984), and 6000 to 7000mgkg -~ at mid-tillering (Elliot et al, 1987).…”