Ameliorative effects of sulphur and humic acid on the growth, antioxidant levels, and yields of pea (Pisum sativum L.) plants grown in reclaimed saline soil

The effects of sulphur (S) and/or humic acid (HA) on the growth, leaf anti-oxidant levels, leaf nutrients, and yields of pea (Pisum sativum L.) plants grown on reclaimed saline soil (EC = 8.2 - 8.5 dS m(-1)) were investigated. Two field experiments were performed in a completely randomised design with four treatments and four replicates for each treatment. Sulphur and HA were applied at the rates of 500 kg ha(-1) or 200 kg ha(-1), respectively, singly or in combination. Neither S nor HA was included in the controls. Soil application of S and/or HA significantly increased shoot lengths, the number of branches plant(-1), leaf area plant(-1), shoot dry weight plant(-1), the contents of leaf pigments, leaf free proline, leaf macronutrients (N, P, and K), seed protein, and the total yields of pods and seeds ha(-1), when compared with non-treated control plants. In contrast, there were significant reductions in leaf Na+ ion contents under the S and/or HA treatments. The combined S + HA treatment was found to be highly effective at improving the growth and yield of pea plants by alleviating the inhibitory effects of soil salinity stress. The same trends were observed over two growing seasons (2010 and 2011).