期刊
REVISTA BRASILEIRA DE CIENCIA DO SOLO
卷 33, 期 5, 页码 1281-1290出版社
SOC BRASILEIRA DE CIENCIA DO SOLO
DOI: 10.1590/S0100-06832009000500021
关键词
Mass flow; soil solution; water deficit; boron deficiency and toxicity
类别
The mechanism and magnitude of B transport to plant roots depend on both water and B soil contents. The contribution of mass flow and diffusion to the B transport in soil to eucalypt roots was evaluated in response to the water potential and B rates. Two water potentials (-10 and -40 kPa) and six B levels (0; 0.5; 1; 2; 3 and 5 mg dm(-3) of B) were evaluated. The plants were grown in 2.5 dm(3) plastic pots with soil, in a greenhouse. The water potential was controlled by a tensiometer in each pot and soil moisture adjusted with distilled water. The maximum root dry weight was produced at rates of 0.98 and 2.38 mg dm(-3) of B, at potentials of -10 and -40 kPa, respectively, and the maximum shoot dry weight at rates of 0.96 and 1.82 mg dm(-3) of B, at potentials of -10 and -40 kPa, respectively. Positive and highly significant relationships were observed between B rates, soil extractable B, B in soil solution and B plant content at both water potentials. Mass flow was the predominant mechanism for B transport in soil, supplying 100 % of the plant demand in the soils treated with the highest B rates. Diffusion was a complementary mechanism, but its relative increased substantially under conditions of low soil B and greater water deficit.
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