This thesis describes studies into the genetic control of tolerance of wheat to high concentrations of boron ( B ). Initially, experiments were conducted to determine selection criteria for distinguishing between tolerant and sensitive genotypes for both glasshouse and field grown wheat. Responses of plants to high concentrations of B, under glasshouse conditions, included reduced vigour, delayed development, expression of symptoms of toxicity and reduced grain and total dry matter yields. Significant differences between tolerant and sensitive genotypes resulted for all parameters, however the greatest discrimination for tolerance to B, between genotypes, resulted during vegetative growth. Tolerant genotypes accumulated less B than the more sensitive genotypes for both glasshouse and field experiments. The concentration of boron in shoots was a highly heritable character and B concentrations in shoots were significantly correlated between high boron conditions in a glasshouse and the field. The concentration of B in grain was highly correlated with the concentration in shoots for field grown wheat, but this relationship did not occur for wheat grown in pots and the anomalous result was related to the artifical growth conditions. Grain is an appropriate tissue for analysis to determine the B accumulation, and therefore tolerance, for field grown wheat. The tolerance to B for wheat varieties of historical importance in Australia was investigated. Many of the historically dominant varieties are tolerant to B and all tolerant Australian varieties are interrelated. The initial tolerant varieties were Federation and Currawa and members of the derived family include Ghurka, Quadrat, Insignia, Heron, Olympic, Halberd, Spear and Dagger. The distribution of Insignia, Heron and Halberd followed a similar pattern in South Australia and the regions where these varieties were most widely cultivated corresponds to the regions where the highest concentrations of B have been measured in barley grain samples. Thus, there is correlative evidence that the high concentration of B occurring in the subsoils has been a major selective force in South Australian wheat production. Tolerance to high concentrations of boron is inherited as an additive character, however expression of tolerance varies from being a dominant to a partially dominant character depending upon the concentration of applied boron. Major gene control of tolerance to boron was identified from the segregation patterns of F2 and F3 generations derived from parents of contrasting tolerance to boron. The parents used represented five levels of tolerance to boron and the difference between successive levels of tolerance was under the control of single genes. Three independent single gene differences were identified. Transgressive segregation resulted between two tolerant lines, Halberd and G61450, and this suggests they have contrasting genes controlling the uptake of boron. A genetic model comprising four independent loci, designated Borl, Bor2, Bor3 and Bor4 was proposed for the five lines. The five lines and their proposed genotypes were : Kenya Farmer ( very sensitive ) borl bor2 bor3 bor4, ( W1 * MMC ) ( sensitive ) borl bor2 Bor3 bor4, Warigal ( moderately sensitive ) borl Bor2 Bor3 bor4, Halberd ( moderately tolerant ) Borl Bor2 Bor3 bor4 and G61450 ( very tolerant ) bor1 Bor2 Bor3 Bor4. As tolerance to high concentrations of B is under the control of major genes, incorporation of tolerance into sensitive but otherwise adapted local varieties should be readily achieved through backcrossing. The chromosomal location of genes controlling tolerance to B was undertaken by the use of intervarietal substitution lines, monosomic analysis and interspecific addition lines. Chromosome 4A of the Chinese Spring - Kenya Farmer substitution lines had a significant effect upon tolerance to boron and the 4A substitution line was more sensitive than Chinese Spring. Results for monosomic analysis were inconclusive, however chromosomes identified as the more probable locations of genes controlling tolerance to boron included 4A and 7D for analysis of the F3 ' s of ( Chinese Spring monosomics * G61450 ) and chromosomes 7B, 3A and 2B for reciprocal monosomic analysis between Chinese Spring and Federation. The Chinese Spring x Ag. elongatum amphiploid was more tolerant than Chinese Spring and the chromosome 7E addition line was also more tolerant than Chinese Spring. The results of three separate comparisons therefore implicate the chromosomes of homoeologous group seven in the control of tolerance to boron. Random F4 and F5 lines derived from the tolerant Halberd and sensitive I ( W1 * MMC ) were tested under naturally occurring high B conditions in the field. Chemical analysis of shoots and grain by inductively coupled plasma spectrometry found uptake of B to be independent of nine other elements. The correlation between tolerance to B, as measured by B uptake, and yield among lines of this population was tested at six sites to identify conditions where tolerance to B resulted in a yield advantage. A significant correlation between tolerance to B and yield resulted only at sites where high boron concentrations of grain resulted. Genetic variation for concentrations of several other elements in shoots and grain also occurred within this population and significant correlations between the efficiency of nutrient uptake and grain yield resulted for Mn at Two Wells and Minnipa while genotypes with low Na accumulation produced significantly higher yields than genotypes with high Na uptake at Rudall. Genetic variation in response to soil elements, other than B, may explain the variable performance of varieties, between environments, and this is an area which warrants further investigation. / Thesis (Ph.D.)--Department of Agronomy, 1990.

1 v. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, Waite Agricultural Research Institute, 1993

Boron deficiency or toxicity can reduce yield and quality of vegetables. Seven vegetable crops, varying from low to high boron requirements were grown in field plots at Corvallis in 1987. Leaf-B and yield components of green bean, cucumber, potato, carrot, tomato, broccoli and table beet were examined under conditions of fall or spring soil applied B at a 5 kg/ha rate on two soil types. Soil tests on control plots indicated B levels of .39 mg/kg and .20 mg/kg in the top 23 cm of soil in the silty clay loam and sandy loam soil, respectively. Fall or spring application of B increased soil B levels in the top 23 cm on the silty clay loam soil to .68 mg/kg and .37 mg/kg, and on the sandy loam soil to .81 mg/kg and .42 mg/kg, respectively. Boron application had no effect on yield or yield components except in green beans where spring applied B on the sandy loam reduced percent of premium grade pods (sieve sizes 1-4). Leaf-B levels were not affected in cucumber, carrot, or tomato on either soil. Boron application on both soils had a significant effect on leaf-B levels in bean, broccoli and table beet. Potato leaf-B was significantly affected only on the sandy loam soil. / Graduation date: 1993

Fundação Araucária / O objetivo deste trabalho foi de avaliar o efeito de datas de coletas e doses de boro nas produções de matéria seca da parte aérea e raízes de alfafa, e os teores de boro e nitrogênio nas plantas e em um Latossolo no Sudoeste do Paraná. O experimento foi conduzido no IAPAR de Pato Branco, PR no ano agrícola de 2011. O delineamento experimental para produção de matéria seca de plantas de alfafa foi de blocos ao acaso com parcelas sub-divididas, com datas de coletas e doses de boro. Para avaliação da matéria seca de raiz (MSR) o delineamento foi de blocos ao acaso com quatro repetições, sendo os tratamentos cinco doses de boro. Para o solo o delineamento foi de blocos aos acaso com parcelas sub-subdivididas com quatro repetições. Onde as parcelas principais se constituíram de coletas, nas subparcelas, cinco doses de boro (0; 0,5; 1; 2; 4 kg ha-1) e nas sub-subparcelas as profundidades (0-5; 5-10 e 10-20cm). A maior produção de matéria seca avaliada por coletas foi encontrada no mês de outubro de 2011, com uma produção de 3.676,6 kg ha-1 e 131,31 kg ha-1 dia-1, respectivamente para matéria seca e taxa de acúmulo. Com relação as concentrações de nutrientes nas plantas as maiores médias foram encontradas nos meses de janeiro, com 81,37 mg kg-1 para boro e em outubro para o nitrogênio com 44,39 mg kg-1. A produção de matéria seca de raízes não foi influenciada pelas doses de boro. A maior concentração, em média, de boro no solo foi de 0,17 mg kg-1. Para o amônio obteve-se os maiores valores de 51,13 mg de NH4 kg-1, em média, no solo na terceira coleta. A máxima eficiência técnica para o nitrato foi com a dose de 2,14 kg de B ha-1, alcançando 52,33 mg kg-1. Além de ter sofrido efeito da interação entre datas de coletas e profundidade variando de 39 a 54 mg kg-1. / The aim of this study was to evaluate the effect of the rates of boron on dry matter production of Alfalfa plants and their roots, and boron and nitrogen concentration in plants in an Oxisol in Paraná, Brazil. The experiment was conducted at Agronomic Institute of Paraná (IAPAR) in Pato Branco town, Paraná, Brazil, in the 2011 agricultural year. The experimental design to the Alfalfa dry matter production was randomized blocks, in subdivided plots, with collection dates and boron doses. To the analysis of root dry matter (RDM) the design a randomized block design was used with four replicates, and treatments of five doses of boron. For the soil the design was randomized block with the sub-divided plots with four replications. In which the main plots consisted of collections, five doses of B (0, 0.5, 1, 2, 4 kg ha-1) in the subplots and in the sub-subplots at 0-5, 5-10 and 10-20 cm depths. The largest dry matter production evaluated by sampling occurred in October 2011, with a production of 3.676,6 kg ha-1 and 131,31 kg ha-1 day-1, for dry matter and accumulation rate, respectively. In relation to the nutrients concentration in plants the highest average was found in January, with 81,37 mg kg-1 of boron concentration, and 44,39 mg kg- 1 of nitrogen, in October. The dry matter production of roots was not affected by boron levels. The highest average boron concentration at the soil was 0,17 mg kg-1. The highest average ammonia levels was 51.13 mg kg-1 of NH4 at the soil in the third collect. The most efficient technique for the nitrate was a dose of 2,14 kg of B ha-1, reaching 52,33 mg kg-1. Besides, an interaction between date and depth was observed from 39 to 54 mg kg-1.

Fundação Araucária / O objetivo deste trabalho foi de avaliar o efeito de datas de coletas e doses de boro nas produções de matéria seca da parte aérea e raízes de alfafa, e os teores de boro e nitrogênio nas plantas e em um Latossolo no Sudoeste do Paraná. O experimento foi conduzido no IAPAR de Pato Branco, PR no ano agrícola de 2011. O delineamento experimental para produção de matéria seca de plantas de alfafa foi de blocos ao acaso com parcelas sub-divididas, com datas de coletas e doses de boro. Para avaliação da matéria seca de raiz (MSR) o delineamento foi de blocos ao acaso com quatro repetições, sendo os tratamentos cinco doses de boro. Para o solo o delineamento foi de blocos aos acaso com parcelas sub-subdivididas com quatro repetições. Onde as parcelas principais se constituíram de coletas, nas subparcelas, cinco doses de boro (0; 0,5; 1; 2; 4 kg ha-1) e nas sub-subparcelas as profundidades (0-5; 5-10 e 10-20cm). A maior produção de matéria seca avaliada por coletas foi encontrada no mês de outubro de 2011, com uma produção de 3.676,6 kg ha-1 e 131,31 kg ha-1 dia-1, respectivamente para matéria seca e taxa de acúmulo. Com relação as concentrações de nutrientes nas plantas as maiores médias foram encontradas nos meses de janeiro, com 81,37 mg kg-1 para boro e em outubro para o nitrogênio com 44,39 mg kg-1. A produção de matéria seca de raízes não foi influenciada pelas doses de boro. A maior concentração, em média, de boro no solo foi de 0,17 mg kg-1. Para o amônio obteve-se os maiores valores de 51,13 mg de NH4 kg-1, em média, no solo na terceira coleta. A máxima eficiência técnica para o nitrato foi com a dose de 2,14 kg de B ha-1, alcançando 52,33 mg kg-1. Além de ter sofrido efeito da interação entre datas de coletas e profundidade variando de 39 a 54 mg kg-1. / The aim of this study was to evaluate the effect of the rates of boron on dry matter production of Alfalfa plants and their roots, and boron and nitrogen concentration in plants in an Oxisol in Paraná, Brazil. The experiment was conducted at Agronomic Institute of Paraná (IAPAR) in Pato Branco town, Paraná, Brazil, in the 2011 agricultural year. The experimental design to the Alfalfa dry matter production was randomized blocks, in subdivided plots, with collection dates and boron doses. To the analysis of root dry matter (RDM) the design a randomized block design was used with four replicates, and treatments of five doses of boron. For the soil the design was randomized block with the sub-divided plots with four replications. In which the main plots consisted of collections, five doses of B (0, 0.5, 1, 2, 4 kg ha-1) in the subplots and in the sub-subplots at 0-5, 5-10 and 10-20 cm depths. The largest dry matter production evaluated by sampling occurred in October 2011, with a production of 3.676,6 kg ha-1 and 131,31 kg ha-1 day-1, for dry matter and accumulation rate, respectively. In relation to the nutrients concentration in plants the highest average was found in January, with 81,37 mg kg-1 of boron concentration, and 44,39 mg kg- 1 of nitrogen, in October. The dry matter production of roots was not affected by boron levels. The highest average boron concentration at the soil was 0,17 mg kg-1. The highest average ammonia levels was 51.13 mg kg-1 of NH4 at the soil in the third collect. The most efficient technique for the nitrate was a dose of 2,14 kg of B ha-1, reaching 52,33 mg kg-1. Besides, an interaction between date and depth was observed from 39 to 54 mg kg-1.

No description available.

Field experiments were conducted during the 1985 growing season on six soils in the Atlantic Coastal Plain region and one from the Piedmont region to determine the response of irrigated corn (<i>Zea mays</i> L.) to boron application. Two treatments applied to each of the soils consisted of 1) a control and 2) both band and foliar boron applied at rates of 2.0 and 0.5 kg ha⁻¹, respectively, as Solubor when corn plants were in the V5 to V6 growth stage. Corn grain yields averaged 13,485 kg ha⁻¹ across treatments on the seven soils. Based on published calibration data for the hot water soluble boron procedure, a corn grain yield response to boron application was not expected on any of the seven soils. Nevertheless, boron application increased corn grain yield from 13,485 kg ha⁻¹ on the control treatment to 14,300 kg ha⁻¹ on the plus boron treatment for one of the seven soils, an Altivista loamy sand. This soil had a hot water soluble boron concentration of 0.56 mg kg⁻¹ and a Mehlich 3 extractable boron concentration of 0.78 mg kg⁻¹. The six soils for which boron application did not increase yields had hot water soluble boron concentrations from 0.55 to 0.92 mg kg⁻¹ and Mehlich 3 extractable boron concentrations from 1.02 to 1.33 mg kg⁻¹. The boron concentration in whole corn plants sampled at the V5 to V6 growth stage was 6.7 mg kg⁻¹ on the Altivista soil where boron application increased corn grain yields and ranged from 9.6 to 103.1 mg kg⁻¹ on the six soils where boron application did not increase yields. The boron concentrations in ear leaves sampled at the early silk growth stage ranged from 8.5 to 18.6 mg kg⁻¹ and in corn grain from 0.66 to 3.31 mg kg⁻¹ on the control treatments of the seven soils. Ear leaf and grain boron concentrations were 10.7 and 0.74 mg kg⁻¹ for plants grown on the control treatment on the Altivista loamy sand, respectively. It can be concluded that, of the plant tissue and soil test procedures evaluated, boron concentration in whole young plants and Mehlich 3 extractable B were the most promising for diagnosis of boron deficiency in corn plants. Nevertheless, research is required on more soils before boron concentrations in young plants and Mehlich 3 extractable B can be used as a routine procedure for detection of boron deficiency in corn plants. / M.S.

Greenhouse and laboratory experiments were conducted to investigate the distribution of native B, the availability of native and applied B in 14 Virginia soils and the specific reactions of B in soil and hydroxy Al and Fe systems. Total B in the 14 soils ranged from 21.5 to 96.3 mg kg⁻¹. Only a small portion of the total B was in soil solution, non-specifically and specifically adsorbed forms and Mn minerals. These fractions of B are readily available to plants. A large part of the total B was associated with non-crystalline and crystalline Al and Fe minerals and soil silicates. These forms of B contribute little to B absorption by plants. Hot water soluble B, NH₄-acetate extractable B, mannitol exchangeable B and Mehlich III extractable B from the soils closely correlated with the concentrations in corn plants from native B in the greenhouse experiment. A yield response of corn plants to B application did not occur on the soils. Both tissue B concentration from applied B and maximum B adsorption by the soils closely correlated with soil clay, hydroxylamine hydrochloride extractable Mn and NH₄—oxalate (pH 3.25) extractable Al and Fe (under UV light). These data indicated that soil clay and Al-, Fe- and Mn-oxides and hydroxides have high affinities to adsorb B in plant unavailable forms. Boron adsorption on both gibbsite and goethite was pH and temperature dependent. At pH 6.5, boric acid was major species in the system and B was absorbed by the negatively charged surface of gibbsite and the positively charged surface of goethite. At pH 10, borate was primarily species in the system and B was adsorbed on negatively charged surfaces of both minerals. Boron adsorption was greater at pH 10 than at pH 6.5. An increase in temperature increased B adsorption on both minerals at both pH levels. This indicated that the B adsorption was an exothermic process. Boron adsorption on gibbsite and goethite shifted the ZPC of the minerals downward. This verified that specific B adsorption occurred on the surfaces. Aluminum substitution in goethite increased the affinity of the surface for B adsorption. / Ph. D.