Effects of Biochar and Biochar–Compost Mix on Growth, Performance and Physiological Responses of Potted Alpinia zerumbet

Abstract

Container crop production has become increasingly popular over the last 50 years. A major component of container or potting media is peat. Peatlands are a natural carbon sink, and peat is a nonrenewable natural resource. Peat harvesting has become an important environmental issue. There is a growing effort to explore alternative organic materials to completely or partially replace peat as a medium component. Biochar is a carbon-rich product that has gained increasing interest as a component of growing media. In the present study, biochar was produced from rice straw. Peat/perlite/biochar (PPB; 40/30/30 v/v) and peat/perlite/biochar/vermicompost (PPBC; 30/30/35/5 v/v) were evaluated relative to a basal or control medium of peat/perlite (PP; 70:30 v/v). Alpinia (Alpinia zerumbet ‘Variegata Dwarf’) was used as a test plant. Amending biochar and biochar–compost mix increased the pH of the growing media. Hydrophysical properties including container capacity, bulk density, air space and total porosity were all within or near the standard ranges for soilless growing media. Chlorophyll a and b contents of A. zerumbet plants grown in PPB medium were reduced by more than 20% and 28%, respectively, compared to those grown in PP or PPBC media. The net photosynthetic rate of PPB-grown plants was more than 28% lower than those grown in PP and PPBC media. As a result, shoot and root dry weights of plants produced in PPB medium were more than 42% and 22% less, respectively, than those grown in PP and PPBC media. Although visual quality of PPB-grown plants was lower, they still exhibited marketable quality, which was largely due to the fact that their side shoots, leaf numbers, leaf areas, leaf thickness, and shoot diameters were comparable to those produced in PP and PPBC media. The present study showed that in a peat/perlite basal medium, substitution of peat by biochar derived from rice straw at 30% affected the growth of A. zerumbet plants, mainly in dry matter accumulation, but the plants were still marketable. On the other hand, plants grown in the same basal medium with peat replaced by the biochar at 35% plus an amendment of compost at 5% were comparable to those grown in the control medium. As the value of ornamental plants depends on their aesthetic appearance, a potting medium comprised of peat/perlite/biochar/vermicompost at 30/30/35/5 by volume is recommended for the production of A. zerumbet plants. The substitution of peat at 35% suggests that peat use can be reduced in the formulation of potting media, thus contributing to the conservation of peatlands.

Biochar: An emerging recipe for designing sustainable horticulture under climate change scenarios

“…In tomatoes, Massa et al (2019) reported decreased chlorophyll SPAD values under normal and nutritional stress conditions using BC. Similarly, Zulfiqar et al (2021b) reported decreased chlorophyll content in A. zerumbet in response to BC supplementation in a soilless growing medium. SPAD values were also higher in tea plants in response to BC application than in untreated plants (Yan et al, 2021).…”

“…Levesque et al (2020) reported improved growth of tomato and sweet pepper in peat-based growing media incorporating 10% or 15% (v/v) BC, with improved plant water use efficiencies, N and P uptake efficiencies, and increased fruit dry weights. In potted Alpinia zerumbet, Zulfiqar et al (2021b) evaluated the impact of BC incorporation in a peat-perlite-based growing medium; growth improved with 30% BC (v/v) alone or in combination with 5% compost by regulating NPK uptake and leaf gas exchange traits. In Rhododendron delavayi Franch., Bu et al (2022) evaluated the impact of two BC (v/v) applications in peatbased growing media, reporting improved plant and root growth, photosynthesis, and contents of carotenoids, polyphenols, and anthocyanins.…”

“…As a result, studies have shown that exogenous BC application improves growth and yield in plants grown under non-stressed or stressed conditions. For example, Zulfiqar et al (2021b) reported improved growth characteristics (plant height, tiller number, shoot diameter, and leaf number) in an important medicinal plant, A. zerumbet, in response to wheat straw-based BC alone and combined with compost. Jabborova et al (2021a) found that BC application improved plant height, leaf length, leaf number, and leaf width in sweet basil relative to control plants.…”

“…(2020) reported improved growth of tomato and sweet pepper in peat-based growing media incorporating 10% or 15% (v/v) BC, with improved plant water use efficiencies, N and P uptake efficiencies, and increased fruit dry weights. In potted Alpinia zerumbet , Zulfiqar et al. (2021b) evaluated the impact of BC incorporation in a peat–perlite-based growing medium; growth improved with 30% BC (v/v) alone or in combination with 5% compost by regulating NPK uptake and leaf gas exchange traits.…”

“…Biochar has a multifunctional role, including GHG sequestration, improving soil properties, seed germination, crop yield and quality of horticulture produce, and increasing crop tolerance to abiotic and biotic stresses ( Kochanek et al., 2016 ; Almaroai and Eissa, 2020 ; Zulfiqar et al., 2021a ; Zulfiqar et al., 2021b ; Ibrahim et al., 2022 ; Ji et al., 2022 ; Taqdees et al., 2022 ) ( Figure 2 ). This review summarizes current progress on using BC to improve soil and substrate properties, seed germination, root growth, water and nutrient absorption, photosynthesis, crop yield, and tolerance to plant pathogens.…”