Boron and Plants

Abstract

Boron is found naturally in the earth's crust in the oxidized form as borax and colemanite, particularly in the oceans, sedimentary rocks, coal, shale, and some soils. It is never found in the elemental form in nature possessing a complex chemistry similar to that of silicon, with properties switching between metals and non-metals. Boron has become an important and strategic element in terms of developing technologies. It is released into the environment mainly through the weathering of rocks, volatilization from oceans, geothermal steam, burning of agricultural refuse and fuel wood, power generators (coal/oil combustion), glass industry, household use of boron-containing products (including soaps and detergents), borax mining and processing, leaching from treated wood and paper, chemical plants, and sewage/sludge disposal, but a major proportion originates from the weathering of rocks. Boron is regarded as an essential element for human beings, animals and plants. Boron occurs in soils at concentrations ranging from 10 to 300 mg kg −1 depending on the type of soil, amount of organic matter, and amount of rainfall. The treatments lead to significant increases in the productivity of some plants but in certain cases a decrease is seen as the boron level increases with the boron content of irrigation water, in particular on the soils with a heavy texture, high CaCO 3 and clay content. Lack of boron in plants results in necrosis but excess amounts are said to produce poisonous effects. Turkey produces more than 60% of the world's borax, with important boron reserves located in Susurluk, Bigadic and Sindirgi regions of Balikesir, Kestelek-Bursa, Emet-Kutahya, the largest reserves occur in Kirka-Eskisehir. Therefore, there is a naturally occurring high level of boron in the ground waters in some of these areas due to the excess amounts of boron given out to the environment during washing and purification processes which result in the pollution of cultivated areas. An attempt will be made here to present an overview of the plant diversity on the boron contaminated soils in Turkey, effects of different concentrations of boron on the germination ability of some plants and possible candidates for phytomining of the soils showing boron toxicity symptoms.

Boron Toxicity Causes Multiple Effects on Malus domestica Pollen Tube Growth

“…In the low rainfall and on highly alkaline and saline soil where the rate of boron is over 2.0 mg/L, there is boron pollution and consequently decreases in production and defect in the products can be seen ( Ozturk et al, 2010 ). When boron is present at high concentrations in the soil or ground water, plant growth, and reproduction can be affected by boron toxicity ( Roessner et al, 2006 ).…”

Soil quality effects on regeneration of annualMedicagopastures in the Swartland of South Africa

“…In general, an extractable amount of less than 0.1 mg kg −1 is regarded as inadequate, yet B may become toxic to some field crops when greater than 1 mg kg −1 (FSSA 2016). Some crops are known to tolerate B up to 5 mg kg −1 (Nable et al 1997;Rashid and Ryan 2004), while Ozturk et al (2009) and Howie (2012) suggested that B may only become toxic to annual medics above 15 mg kg −1 . Phytotoxicity is therefore not expected to have occurred at the concentrations observed in this study.…”

Salicylic Acid Stimulates Antioxidant Defense and Osmolyte Metabolism to Alleviate Oxidative Stress in Watermelons under Excess Boron

“…Watermelon belongs to the Cucurbitaceous family and is considered one of the world's top 20 cultivated crops with elevated economic value. The principal countries producing watermelon, such as China and Turkey [41,42], are affected by B stress, which has drastic effects on watermelon growth and yield. Nevertheless, there is insufficient knowledge on the mechanisms of boron toxicity-induced watermelons injury [4], highlighting the importance of alleviating B stress in watermelon crops.…”