Thesis (Ph.D. 1973) from the Dept. of Agricultural Biochemistry and Soil Science, University of Adelaide.

vii, 122 leaves : ill. ; 25 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1973) from the Dept. of Agricultural Biochemistry and Soil Science, University of Adelaide

vii, 122 leaves : ill. ; 25 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1973) from the Dept. of Agricultural Biochemistry and Soil Science, University of Adelaide

The effect of boron deficiency was studied in tomato plants grown hydroponically. Morphological studies showed that boron deficiency in the root system caused a cessation of root elongation, browning and thickening of root tips, the formation of branch roots close to the apex and decrease in the overall size of the root. The pyrimidine biosynthetic pathway remained intact and functional under boron limitation. The sugar nucleotide, uridine diphosphate glucose, was diminished in boron deficient medium and its level was restored to that of born sufficiency when uracil, cytosine, uridine, cytidine or orotic acid was provided.

The most apparent symptom of boron deficiency in higher plants is a cessation of growth. Deficiency causes a reduction in ascorbate concentration and the absorption of nutrient ions. Addition of ascorbate temporarily relieves deficiency symptoms. In boron sufficient plants the addition of ascorbate to media causes an increased uptake of nutrients. In an attempt to discover if ascorbate addition to deficient plants causes increased ion uptake, radish plants were grown hydroponically in four different strengths of boron solution. A colorimetric assay for phosphorus was performed both before and after supplementation. Results, however, were inconclusive.

Submitted by JORGE MARTINELLI MARTELLO (jorgemartinelli@hotmail.com) on 2016-02-29T20:47:16Z No. of bitstreams: 1 DISSERTAÇÃO- JORGE MARTINELLI.pdf: 16363477 bytes, checksum: e325bf527b7f461e3d998472d2084c38 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-03-01T13:47:45Z (GMT) No. of bitstreams: 1 martello_jm_me_bot.pdf: 16363477 bytes, checksum: e325bf527b7f461e3d998472d2084c38 (MD5) / Made available in DSpace on 2016-03-01T13:47:45Z (GMT). No. of bitstreams: 1 martello_jm_me_bot.pdf: 16363477 bytes, checksum: e325bf527b7f461e3d998472d2084c38 (MD5) Previous issue date: 2016-01-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Recentemente no Brasil, a deficiência de boro têm sido constatada tanto em regiões tradicionais mas, principalmente, em regiões de expansão da cultura da cana-de-açúcar para solos arenosos e de baixa fertilidade. Relacionado a isso, doenças como estria vermelha (Bactéria - Acidovorax avenae), além de redução qualitativa e quantitativa da produtividade dos canaviais, têm sido observados. Portanto, estudos mais detalhados que revelem com maior clareza as particularidades deste micronutriente para a cultura se fazem necessários. Assim, objetivou-se com o presente trabalho avaliar o efeito da disponibilidade de boro em solução nutritiva sobre o desenvolvimento radicular e da parte aérea e, também, sobre a eficiência na absorção e concentração de nutrientes em duas variedades de cana-de-açúcar de ciclos semelhantes e recomendadas para o mesmo ambiente de produção. O experimento foi realizado em casa de vegetação, na Faculdade de Ciências Agronômicas /UNESP, em Botucatu-SP, Brasil. O delineamento experimental foi inteiramente casualizado com esquema fatorial composto por duas variedades (1- RB867515 e 2- RB92579) e, duas concentrações de B na solução nutritiva (1-Deficiente: 4,5 μmol L-1 e 2-Adequado: 45 μmol L-1 de B), totalizando quatro tratamentos com quatro repetições. Foram avaliados os parâmetros biométricos das plantas e morfológicos das raízes, a produção de matéria seca, a concentração e o acúmulo de nutrientes na parte aérea, e a quantidade de nutrientes absorvidos por metro de raiz. Os dados foram submetidos à análise de variância e aplicação do teste LSD a 5% de significância para as médias obtidas. O desenvolvimento e o comprimento radicular e dos entrenós das plantas de cana-de-açúcar foram restringidos pela deficiência de boro e, a concentração de nutrientes na parte aérea também foi reduzida. A variedade RB92579 apresentou maior produção de MSRA, MSC, MSF, menor diâmetro radicular e maior AP em relação a variedade RB867515, sob baixa concentração de B. As variedades de cana-de-açúcar estudadas comportam-se de maneira diferente frente a baixa disponibilidade de boro na solução nutritiva, sendo a variedade RB92579 mais tolerante e a variedade RB867515 mais suscetível a deficiência de boro. / Recently in Brazil, boron deficiency has been verified both in traditional, but mainly in expanding regions of the sugarcane crop to areas with sandy and low fertility soils. Associated with that, diseases like red stripe (Bacteria - Acidovorax avenae), as well as, qualitative and quantitative reduction in the productivity of sugarcane plants, have been observed. Therefore, more detailed studies, in order to further clarify special features of this micronutrient for the crop, become necessary. Thus, the aim of the present study was to evaluate the effect of boron availability in nutrient solution, on the root and shoot growth, and also on the nutrient uptake efficiency and concentration in two sugarcane varieties with similar growth cycles, that are recommended for the same growth environment. The experiment was conducted in a greenhouse at the College of Agricultural Sciences – Department of Crop Science/UNESP, in Botucatu-SP, Brazil. The experimental design was completely randomized in a factorial composed of two varieties (1- RB867515 and 2- RB92579) and two boron concentrations in the nutrient solution (1-Deficient: 4,5 μmol L-1 and 2-Adequate: 45 μmol L-1 B), four treatments with four repetitions in total. Were evaluated, the biometric parameters of plants, root morphology, dry matter yield, nutrient concentration and uptake in shoots and the uptake of nutrients by root length unit. Data were subjected to the variance analysis and means compared by the LSD test at 5 % significance. The root length and internodes development of sugarcane plants were restricted by boron deficiency and the concentration of nutrients in shoots was also reduced. The variety RB92579 showed higher production of MSRA, MSC, MSF, smaller root diameter and larger AP regarding RB867515 variety, under low boron concentration. The varieties of sugarcane studied, behave in a different way across the low availability of boron in the nutrient solution, being variety RB92579 more tolerant, and variety RB867515 more susceptible to boron deficiency. / CAPES: 3300406-4

The incidences of suspected Boron (B) deficiency have increased recently in Kentucky tobacco fields, potentially due to recent changes in management practices. The symptoms observed in the field include; hollow stalk, stunted growth, deformed or no bud formation, small slits on the lower leaf midrib and uncontrollable breaking of the midrib approximately two inches from the stalk. B is a micronutrient tobacco needs in minute amounts, however excessive additions of B could cause toxicity. The objectives of this work were to 1) establish critical points for B sufficiency, 2) describe and define B deficiency and toxicity symptoms and 3) develop field strategies to aid in the mitigation of B deficiency. A general nutrient response curve was generated utilizing solution culture experiments. The peak of the response curve appeared to occur at solution B concentration of 100 µM. Trace-levels of B contamination and small plant size in the solution culture limited the development of deficiency symptoms. Toxicity was observed at solution concentrations of 400 µM and above. Despite choosing sites with a history of B deficiency, deficiency symptoms were not observed during this study. Toxicity was observed when 0.56 kg B/ha or greater was applied as simulated transplant water treatments. No toxicity was observed when B was applied as a soil broadcast or foliar application. Recommendations are to apply B with caution as a broadcast application to avoid potential problems with toxicity. Additional research is required to refine the nutrient response curve and better understand B deficiency.