Intact-plant screening for tolerance of nutrient-deficiency stress

Abstract

SummaryCritical factors in the selection of appropriate screening procedures to detect different phenotypic responses to nutrient-deficiency stress are discussed. Various morphological, anatomical, and physiological plant factors responsible for adaptations to nutrient deficiency, particularly low-P stress, are reviewed. Also, the relative effectiveness of various screening culture techniques for detecting phenotypic efficiencies based on specific plant features are considered.The relative ineffectiveness of liquid culture media in detecting plant factors critical in P acquisition from low-P natural environments is recognized, and a culture medium that is effective under these conditions is described. P adsorbed onto alumina, after mixing with coarse sand, serves as a P source in nutrient cultures. Buffered P concentrations approximating soil solution concentrations are maintained in this system, and P availability at the root surface seems diffusion-limited. With this system, significant differences in the growth of tomato strains under P stress were detected.The desirability of screening phenotypes at the same degree of depression from maximum yield (equivalent deficiency stress) is discussed. The need for evaluations at equivalent stress is associated with the capacities of plants in general to respond to deficiency stress with morphological and physiological changes that may not be under genetic control, for example an increase in root:shoot ratio. Additional capacity to adjust the same plant factors often are characteristic of specific phenotypes. The relative growth of the same tomato strains under equivalent and non-equivalent P-deficiency stress is compared. Significant strain differences were observed under both conditions. However, the relative responses among strains for several efficiency parameters were very different under the two types of stress.

Phosphorous Use Efficiency of Safflower and Sunflower Grown in Different Soils

“…Different concepts of nutrient efficiency have been developed, some giving emphasis to productivity and others to internal nutrient requirement [17], and in some cases their interpretations are misleading [6,9]. To characterize different plant species or genotypes for NUE, researchers use many criteria, including the presence or absence of deficiency symptoms [44], absolute growth at a limiting nutrient level [45], relative growth obtained by comparing growth at limiting and adequate nutrient levels [46], efficiency ratio (ER) or amount of biomass produced per unit of nutrient present in the tissues [47], the use of yield response curves in terms of the functional relationship between yield and nutrient accumulated in the aboveground biomass, or nutrient supply in nutrient media using Michaelis-Menten-type equation [9,10,11,13], and utilization coefficient as the inverse of the whole plant nutrient concentration being expressed on a dry matter basis [13]. The plants nutrient efficiency could be also assessed by other terms like the "external" and "internal" P requirements for plant growth and yield under limited nutrient availability in soil.…”

Mineral nutrient calibration for Cassava (Manihot esculenta Crantz) grown in dry-tropical North-Eastern Queensland, Australia: with a focus on Phosphorus and Boron

“…Stem P concentration in Avoca increased with increasing P application, from 0.16% at 0 kg/ha to 0.32% at 120 kg/ha P rate in Avoca (Figure 4.11 right). This result was consistent with the findings in Gerloff (1987) where reduced allocation of P in supporting structures, such as stems, occurred due to the plant adaptation to low P environment. A strong negative correlation (r 2 =0.73, p<0.001) between PUE and stem P concentrations occurred regardless the cultivar (Figure 4.11 left).…”

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

“…Additionally, the case was made that because soil is the medium in which plant selections ultimately must perform, cultivar screening for nutrient efficiency in solution culture (nutricuIture) should relate to results in soil (Gerloff, 1987). While the nutriculture method facilitates screening large numbers of plants and eliminates some of the physiochemical complexities involved in soil studies, systeminduced variations in nutrient availability, as well as plant morphological, anatomical, and physiological factors with nutriculture might result in genotypic variation in NUE different from those which would occur in soil.…”