Boron affects the growth and ultrastructure of castor bean plants

Abstract

The cultivation of oleaginous plants like the castor bean guarantees employment for agricultural families and can contribute in energy and chemical sectors, especially in the northeastern semi-arid regions of Brazil. Boron (B) deficiency is a widespread nutritional disorder despite the fact that various anthropogenic sources with high B content may increase soil B to toxic levels for plants. The present study was designed to investigate the ultrastructural effects of boron deficiency and toxicity on castor bean plants which were grown under greenhouse condition using plastic containers with 10 L of nutrient solution. Boron treatments comprised: control (no B); 0.27 mg L -1 , 5.40 mg L -1 B pots (one plant per pot), tested in a completely randomized design with three replicates. The dry matter of all plant parts and B concentration were determined. Cellular ultrastructure was evaluated by transmission and scanning electron microscopy on samples of leaves and petioles. Dry matter yield was affected by the B absence treatment but there was no difference for the 5.4 mg L -1 B (toxic conditions) treatment. A marginal leaf burn at edge and tips of oldest leaves and absence of starch granules in chloroplasts were noted for the B toxicity treatment. The deformation of the youngest leaves, the death of the apical meristem as well as the swelling of the middle lamella, absence of starch granules in chloroplasts and petiole vessels untidily were observed in the B absent treatment. It is concluded that the production and development of castor bean plants is affected by boron deficiency, but not for boron toxicity conditions.

Deficiency symptoms and uptake of micronutrients by castor bean grown in nutrient solution

“…the fruits (seeds plus capsules), with adequate and moderate b supply, accumulated 24 % (151.2 µg/plant) and 27 % (100.0 µg/plant) of the total amount accumulated by the plants, respectively. it is known that the long-distance transport of b in plants is influenced by the transpiration flow in the xylem, and the more developed this organ is, the greater will be the leaf area or presence of stomata and consequently the higher the transpiration rate (Silva et al, 2008;eichert & Goldbach, 2010), possibly explaining these results. moreover, it is worth noting the differences in the b accumulation between seed and capsule in both treatments (figure 2).…”

Boron deficiency alters root growth and development and interacts with auxin metabolism by influencing the expression of auxin synthesis and transport genes

“…[7] Boron deficiency has severe negative effects on plants, including induction of male sterility in wheat, rice and maize, [5,6] the reduction of root biomass and nodules in legumes [8] and the deformation of new leaves and hyperplastic petioles in castor beans. [9] In citrus, boron deficiency causes leaf senescence, decreases the tree vigour and reduces the fruit yield and quality. [10,11] It also causes corky split veins to occur in mature leaves.…”

Crescimento e aspectos sintomatológicos na aclimatização de Ipê-roxo

“…Prado et al (2007) afirmam que plantas com falta de cálcio e magnésio apresentam clorose internerval e necrose das regiões cloróticas; o que corrobora com os resultados obtidos neste trabalho. A deficiência de boro provoca desorganização do sistema vascular e, consequentemente, morte do meristema apical (SILVA et al, 2008), o que também foi observado no tratamento que utilizou água destilada na suplementação hídrica das plantas de Ipê-roxo.…”