Growth Inhibition of Cucumber by Absorbing Excess Al at Low Soil pH

Abstract

On-site diagnosis applied to soil having a symptom of yellowing and whitening in cucumber leaf and stem. Soil pH determined 4.2 by methods of on-site analysis and 4.5 by soil test analysis. High aluminum in soil solution extracted with water saturation was detected. Leaf and stem tissue were abundant in Al content but not in Ca. Also, N content of leaf and stem was low compared to normal N ranges. This symptom of cucumber assumed to be from the Al and nitrous acid gas toxicity by low soil pH and Eh. Conclusionally, symptom in leaf and stem of cucumber was alleviated and cucumber normally recovered during cultivation period by applying calcium hydroxide solution to correct soil pH up to 6.5. These results showed that low soil pH resulted in aluminum toxicity and N deficiency to plant growth in on-site farming.

Emission of NO2Gas Causing Damage to Plants in an Acid Soil under Conditions Favorable for Denitrification

“…In this study, in the acid soil prepared for high rate of denitrification, 36.4 mg N kg -1 of NO2 -was found even after the 5 days of incubation (Table 4). Thomsen et al (1994) (Kim et al, 2010(Kim et al, , 2012. Although NO2 emission and its damaging effect were identified in the wet acid soils containing NO3 -, NO2 -accumulation and NO2 production were completely inhibited when the soil was sterilized (Table 5 and 6).…”

“…Also NO2 gas injury was found in fig trees grown in containers with application of nutrient solution containing 200 mg N L -1 of NO3 -, and pH of the artificial soil in the containers was 5.5 (Kim et al, 2010). Kim et al (2012) reported NO2 gas injury in cucumber plants grown in acid soil (pH 4.8) of plastic film house where soil NO3 content was 500 mg L -1 . Considering those incidences of NO2 gas damage to crop plants, NO2 emission is closely related to the NO3 -applied as a nitrogen fertilizer and also to the acidic soil pH.…”