Boron: More Than an Essential Element for Land Plants?

Although boron (B) is an element that has long been assumed to be an essential plant micronutrient, this assumption has been recently questioned. Cumulative evidence has demonstrated that the players associated with B uptake and translocation by plant roots include a sophisticated set of proteins used to cope with B levels in the soil solution. Here, we summarize compelling evidence supporting the essential role of B in mediating plant developmental programs. Overall, most plant species studied to date have exhibited specific B transporters with tight genetic coordination in response to B levels in the soil. These transporters can uptake B from the soil, which is a highly uncommon occurrence for toxic elements. Moreover, the current tools available to determine B levels cannot precisely determine B translocation dynamics. We posit that B plays a key role in plant metabolic activities. Its importance in the regulation of development of the root and shoot meristem is associated with plant developmental phase transitions, which are crucial processes in the completion of their life cycle. We provide further evidence that plants need to acquire sufficient amounts of B while protecting themselves from its toxic effects. Thus, the development of in vitro and in vivo approaches is required to accurately determine B levels, and subsequently, to define unambiguously the function of B in terrestrial plants.

Shoot and root responses of Trifolium vesiculosum to boron fertilization in an acidic Brazilian soil

To analyze the influence of boron fertilization on shoot and root growth of Trifolium vesiculosum (arrowleaf clover), an acid soil profile (60 cm depth with 67 percent Al saturation) was recreated in a column (three layers of 20 cm each). Lime and fertilizer (P and K) were incorporated into the top 20 cm. The treatments consisted of six boron rates where boric acid was mixed throughout the profile. Addition of boron to soil with low pH and high Al increased the root and shoot growth, independent of the rate applied. Boron inhibited Al toxicity, but no effect was observed in the root length when Al was not present in the soil. It was also observed that there was more root growth below the plow layer (0-20 cm,) suggesting better root distribution in the soil profile which could be important for the plant growth, especially under drought conditions.

Estudos têm mostrado que o boro (B) afeta o crescimento das raízes em solo ácido reduzindo a toxidez do alumínio (Al). Para analisar a influência do boro no crescimento da parte aérea e raízes do Trifolium Vesiculosum (trevo vesiculoso) um perfil de solo ácido (60 cm de profundidade com 67 por cento de saturação de Al) foi recriado em uma coluna (três camadas com 20 cm cada). Calcário e adubos (P e K) foram incorporados na camada de 0-20 cm. Os tratamentos consistiram de seis doses de boro sendo o ácido bórico incorporado em todo o perfil. A adubação com boro em solo com baixo pH e elevado Al aumentou o crescimento da parte aérea e raízes, no entanto, independente da dose aplicada. Boro pode inibir a toxidez de Al, porém não observou-se efeito no comprimento de raízes sem a presença de Al no solo. Observou-se também um grande aumento no crescimento de raízes abaixo da camada arável (0-20 cm), fornecendo uma melhor distribuição de raízes no perfil do solo, o que pode ser importante para o crescimento da planta especialmente em condição de seca.

Evaluation of shoot growth and fruitful buds of niagara rosada grape submitted to different units of pruning / Avaliação da brotação e da fertilidade de gemas da videira niagara rosada submetida a diferentes intensidades de poda de frutificação

This research was an attempt to evaluate different units and dates of pruning for Niagara Rosada grape produced out of season in the Northwest of Parana state, Brazil. The trial was carried out in a 5-year-old commercial vineyard budded on Riparia do Traviú rootstock, located at Marialva city, PR. The vineyard was trained in a horizontal bilateral cordon and planted in a 2,0 m x 1,0 m spacing. The following treatments were evaluated according to the number os buds left on cane or spur: a. cane-pruning (6-8 buds) on january 5th, 2001; b. half-long pruning (4-5 buds) on january 5th, 2001; c. spur-pruning (1-2 buds) on january 5th, 2001; d. cane-pruning (6-8 buds) on january 19th, 2001; e. half-long pruning (4-5 buds) on january 19th, 2001; f. spur-pruning (1-2 buds) on january 19th, 2001. All treatments were applied after the harvesting originated from winter pruning made on July, 2000. A randomized block with 6 treatments and 4 replications in a 3 x 2 factor design (3 units of pruning x 2 periods) was used as a statistical model. Each plot was composed by 4 trees. The following parameters were compared through variance analysis: porcentage of shooting buds and porcentage of shooting buds with clusters. Spur-pruning treatments (1-2 buds) showed the lowest averages for shooting and porcentage of shooting buds with clusters, whereas the cane and half-long pruning treatments (6-

O presente trabalho teve por objetivo avaliar a aplicação de diferentes intensidades e épocas de poda de frutificação para a produção fora de época da videira Niagara Rosada na região noroeste do Paraná. O ensaio foi conduzido em uma plantação comercial de 5 anos de idade enxertada sobre Riparia do Traviú, localizada no município de Marialva, PR, conduzida no sistema de espaldeira em cordão bilateral em espaçamento 2,0 m entre linhas por 1,0 m entre plantas. Foram estudadas as seguintes intensidades de poda em relação ao número de gemas deixadas por sarmento ou esporão: a. poda longa (6-8 gemas), época 1 (05/01/2001); b. poda média (4-5 gemas), época 1 (05/01/2001); c. poda curta (1-2 gemas), época 1 (05/01/2001); d. poda longa (6-8 gemas), época 2 (19/01/2001); e. poda média (4-5 gemas), época 2 (19/01/2001); f. poda curta (1-2 gemas), época 2 (19/01/2001). Todos os tratamentos foram aplicados após a colheita originada da poda de inverno realizada em julho de 2000. O delineamento experimental foi o de blocos ao acaso, com 6 tratamentos e 4 repetições, em esquema fatorial 3 x 2 (3 intensidades de poda x 2 épocas de poda), sendo cada parcela constituída por 4 plantas. Foram comparados, através de análise de variância, os seguintes parâmetros: porcentagem de gemas brotadas e; porcentagem de gemas brotadas com cachos. A poda curta (1-2 gemas) apresentou as menores médias para

Evaluation of shoot growth and fruitful buds of niagara rosada grape submitted to different units of pruning / Avaliação da brotação e da fertilidade de gemas da videira niagara rosada submetida a diferentes intensidades de poda de frutificação

This research was an attempt to evaluate different units and dates of pruning for Niagara Rosada grape produced out of season in the Northwest of Parana state, Brazil. The trial was carried out in a 5-year-old commercial vineyard budded on Riparia do Traviú rootstock, located at Marialva city, PR. The vineyard was trained in a horizontal bilateral cordon and planted in a 2,0 m x 1,0 m spacing. The following treatments were evaluated according to the number os buds left on cane or spur: a. cane-pruning (6-8 buds) on january 5th, 2001; b. half-long pruning (4-5 buds) on january 5th, 2001; c. spur-pruning (1-2 buds) on january 5th, 2001; d. cane-pruning (6-8 buds) on january 19th, 2001; e. half-long pruning (4-5 buds) on january 19th, 2001; f. spur-pruning (1-2 buds) on january 19th, 2001. All treatments were applied after the harvesting originated from winter pruning made on July, 2000. A randomized block with 6 treatments and 4 replications in a 3 x 2 factor design (3 units of pruning x 2 periods) was used as a statistical model. Each plot was composed by 4 trees. The following parameters were compared through variance analysis: porcentage of shooting buds and porcentage of shooting buds with clusters. Spur-pruning treatments (1-2 buds) showed the lowest averages for shooting and porcentage of shooting buds with clusters, whereas the cane and half-long pruning treatments (6-

O presente trabalho teve por objetivo avaliar a aplicação de diferentes intensidades e épocas de poda de frutificação para a produção fora de época da videira Niagara Rosada na região noroeste do Paraná. O ensaio foi conduzido em uma plantação comercial de 5 anos de idade enxertada sobre Riparia do Traviú, localizada no município de Marialva, PR, conduzida no sistema de espaldeira em cordão bilateral em espaçamento 2,0 m entre linhas por 1,0 m entre plantas. Foram estudadas as seguintes intensidades de poda em relação ao número de gemas deixadas por sarmento ou esporão: a. poda longa (6-8 gemas), época 1 (05/01/2001); b. poda média (4-5 gemas), época 1 (05/01/2001); c. poda curta (1-2 gemas), época 1 (05/01/2001); d. poda longa (6-8 gemas), época 2 (19/01/2001); e. poda média (4-5 gemas), época 2 (19/01/2001); f. poda curta (1-2 gemas), época 2 (19/01/2001). Todos os tratamentos foram aplicados após a colheita originada da poda de inverno realizada em julho de 2000. O delineamento experimental foi o de blocos ao acaso, com 6 tratamentos e 4 repetições, em esquema fatorial 3 x 2 (3 intensidades de poda x 2 épocas de poda), sendo cada parcela constituída por 4 plantas. Foram comparados, através de análise de variância, os seguintes parâmetros: porcentagem de gemas brotadas e; porcentagem de gemas brotadas com cachos. A poda curta (1-2 gemas) apresentou as menores médias para