Biochar Application and Drought Stress Effects on Physiological Characteristics of Cucurbita pepo

Biochar Application and Drought Stress Effects on Physiological Characteristics of Cucurbita pepo

The objective of this study was to investigate the effects of biochar on physiology and yield of pumpkin (Cucurbita pepo L.) under different irrigation regimes. For this purpose, a randomized complete block design with four replicates was conducted in Gorgan, northern Iran, at two successive years (2014-2015) and consisted of a factorial combination of four irrigation regimes including 45%, 60%, 75% and 90% (I1–I4) of maximum allowable depletion (MAD) of available soil water (ASW) and biochar derived from maize-straw feedstock was applied at rates 0, 5, 10 and 20 t biochar ha−1 ( B0–B20). Drought increased the activity of antioxidant enzymes, and the content of malondialdehyde (MDA), oxygen radicals (O2•−), and hydrogen peroxide (H2O2) in leaf compared to control. In contrast, all of the antioxidant activities and proline contents of leaves in soil treated with biochar, particularly at B20 biochar, declined. With the addition of biochar, the contents of MDA, O2•− and H2O2 displayed remarkable decrease. Amendments with biochar increased chlorophyll content and the higher uptake of nutrients in leaves regardless of irrigation regimes. Interestingly, Biochar application allayed the negative impact of reduce irrigation on the leaf gas exchange parameters, crop yields, water use efficiency (WUE) and plant water status. The seed yield showed a decrease of 6%, 46% and 58% in I2, I3 and I4 in comparison with I1 regardless of biochar applied rate. These results indicate that biochar amendment could provide a win-win strategy for improve the physical status of agricultural soils, water productivity and increased crop production in Mediterranean condition.