Search Results
Abstract
Plants growing in nature provide a continuous array of biological efficiencies related to mineral nutrition. Nearly all of the temperate and tropical areas of the earth are covered with species adapted to the unique properties of particular soils. These properties may represent the extremes in element availability from very deficient to toxic levels and may be associated with wide ranges in pH.
Abstract
Genetic control of root development in beans was investigated in the parents, F1, backcrosses and F2 obtained from 6 crosses made among 6 lines obtained from an earlier study of efficiency in P utilization. One line produced significantly larger and more vigorous roots and a narrower shoot/root ratio than the other 5 lines, both at stress and at adequate levels of P. Quantitative inheritance patterns and transgressive segregation for root dry weights were observed and high broad sense heritability estimates were obtained. Dominance variance was more important than additive variance in 4 families.
Abstract
The concept of genetic control of efficiency of nutrient utilization in tomatoes was investigated within naturally occurring variation among 146 strains. Under severe N stress (35 mg of N per plant) in nutrient culture solutions efficient strains produced as much as 45% more dry weight than inefficient strains. Efficiency in N utilization (NER) was defined as the mg of dry weight produced for each mg of N absorbed by a plant. Differences in N uptake and translocation by the root systems did not explain variations in efficiency. At equal total N concentrations in leaves, efficient plants produced larger lower leaves and maintained more normal tissues. High NER values for efficient strains also were associated with greater stem weights and lower total N concentrations. Inheritance studies showed that dominance and additive X additive gene effects made the major contributions to variation in both plant dry weight and N efficiency.
Abstract
Genetic control of efficiency in K utilization was investigated by screening 156 lines of tomato (Lycopersicon esculentum Mill.) in nutrient culture solution (one plant per container) at a stress level of K (5 mg per plant). Efficiency in K utilization was defined and expressed as the mg of dry weight produced per mg of K absorbed by a plant (KER). Under K stress, an efficient line produced an average of 79% more dry wt than an inefficient line. Yields of the lines were comparable under adequate K (200 mg per plant). The efficient lines contained 39% less K and 29% more Na in their tissues when grown at the low levels of K. Differences in K uptake or translocation of K from roots to shoots could not explain variations in efficiency of K utilization. Partial substitution of K by Na was important in high K efficiency. However, part of the efficiency was associated with K functions for which Na could not substitute. One line responded favorably to Na even at moderate levels of K. Additive gene effects made the major contribution to variation in efficiency of K utilization. Dominance and epistatic gene effects were important only in 1 of the 4 inefficient × efficient families and in families derived from parents of similar efficiency. No evidence for maternal control of efficiency in K utilization was observed.
Abstract
Tomato cultivars developed in Brazil, Hawaii, and different parts of the continental United States differed significantly in their tolerance to an acid (pH 4.2), Al-toxic Bladen soil. Cultivars showing greatest tolerance included ‘BGH 588’ (Brazil), ‘Ace’ (Calif.) and Owyhee’ (Idaho); those showing low tolerance included ‘BGH 402’ (Brazil), Anahu’ (Hawaii), and Truckers Favorite’. Differential Al tolerances of ‘BGH 588’, ‘BGH 402’, and ‘Truckers Favorite’ were confirmed in nutrient solutions containing a range of Al concentrations. Tolerance to Al-toxic Bladen soil, measured by vegetative growth, was not associated with reported resistance to blossom end rot (Ca deficiency).
Cultivars showing the greatest tolerance to acid Bladen soil tended to contain lower concentrations of Al, Ca, and P in their tops than did the more sensitive cultivars. In nutrient solutions containing Al, the tops of Al-tolerant and Al-sensitive cultivars generally contained similar concentrations of Al, P, and Ca. Roots of tolerant cultivars tended to contain lower concentrations of Al and P and sometimes Ca.
Results suggest the possibility of developing tomato cultivars specifically for greater tolerance to acid soil environments which cannot be economically corrected. An example would be strongly acid Al-toxic soil zones beneath the plow layer.
Abstract
Variability within the plant kingdom for nutrient acquisition and use reflects differences in root morphology and differences in mechanisms that either aid or prevent ion movement into the root. This variability implies genetic variance, yet few genetic studies have been completed. Methods of studying acquisition and their application to genetic research and interpretation are presented for K, Ca, and P.
Abstract
A sand medium containing activated alumina was developed to provide a range of stable, reproducible P concentrations in plant cultures. The lowest P levels compare favorably to concentrations found in soils. Activated alumina was “loaded” by absorption of phosphate from 0.01 m NaCl solutions containing KH2PO4. Phosphorus concentrations in solutions expressed from sand-alumina mixtures were dependent upon the P concentrations used to absorb P onto the alumina. Increasing the density of a specifically loaded alumina did not affect the average solution P concentration in the cultures but did result in substantial increases in total dry weight yields of tomato (Lycopersicon esculentum Mill.) plants grown in the cultures. Thus, diffusion of P to root surfaces seems to be a prominent limiting factor in this system as in soils. The sand alumina culture technique shows promise for simulating plant responses to P at concentrations and under conditions comparable to those found in soils.
Abstract
One hundred tomato (Lycopersicon esculentum Mill.) strains were grown under low-K stress (0.071 mm K) in the absence and presence of added Na to identify strain differences in efficient K use, efficient substitution of Na for K, and upper leaf Na accumulation. Five strains, selected as representing extreme differences for K efficiency and Na substitution capacity, were used as parents to create a series of F1, F2, and backcross generations to study the inheritance of K efficiency, Na substitution, and upper leaf Na accumulation of tomatoes grown under low-K stress. Reciprocal differences in the F1 generation were relatively unimportant in the inheritance of K efficiency, Na substitution capacity, and Na accumulation. K efficiency in the absence of Na was a trait of low heritability, with highly significant additive, dominance, and additive × additive epistatic effects. Na substitution capacity was highly heritable, with highly significant additive and dominance effects. Na accumulation also was highly heritable, with highly significant additive effects. Moderately high correlations were observed between Na accumulation and Na substitution capacity within genetically segregating generations.
Abstract
Differential plant response to Ca-deficiency stress was investigated by screening 138 tomato lines (Lycopersicon esculentum Mill.) in nutrient solution at 10 mg of Ca per plant. Dry weight produced during vegetative growth and severity of Ca-deficiency symptoms were used to classify plants as efficient and inefficient. Efficiency in Ca utilization within the plant was defined and expressed as the mg of dry weight produced for each mg of Ca absorbed by a plant (CaER). Three of the most efficient and 3 of the most inefficient lines were selected for additional studies. The efficient lines produced an average of 81% more dry weight than the inefficient lines at 10 mg of Ca. Comparable amounts of dry weight were produced by all lines at 400 mg of Ca per plant. Two factors were responsible for greater dry weight production under Ca-deficiency stress: more efficient utilization of tissue Ca and greater ability to absorb Ca from low-Ca solutions. Inheritance studies indicated that additive gene effects made major contributions to variations in response to low Ca. A simple additive-dominance model was adequate to explain differences in CaER, with additive effects highly significant. Some interallelic interactions appear to be important for total plant dry weight inheritance.
Abstract
Bean (Phaseolus vulgaris L.) lines were screened for efficiency of P utilization in nutrient culture at 2 mg P per plant (seed P + added P). The P in the nutrient cultures was removed rapidly and nearly all the P stored in cotyledons was exported before abscission. From 54 lines screened, 6 were selected to represent extremes in response to P stress and were classified as efficient, moderately inefficient, and inefficient based on dry weight production and P efficiency ratio (PER) defined as the mg dry weight yield per mg of P in the tissue. PER values for top dry weight production at 2 mg of P varied from 380 to 671 mg. In some lines, growth increased as solution P increased to relatively high levels; in other lines there was no growth response. Under P stress, net photosynthesis per unit of P was higher in an efficient than in an inefficient line. Thus, 1 factor in P efficiency was concluded to be associated with photosynthetic metabolism. Inheritance of P efficiency based on top dry weight varied among different matings. Reciprocal hybrids indicated little or no maternal inheritance of efficiency.