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Impact of a Biochar or a Compost-Biochar Mixture on Water relation, Nutrient uptake and Photosynthesis of Phragmites karka

Zainul, Abideen, KOYRO, Hans-Werner, HUCHZERMEYER, Bernhard, GUL, Bilquees, KHAN, M. Ajmal
Pedosphere 2017
Phragmites, biochar, bioenergy, biomass production, calcium, carbon dioxide, chlorophyll, clay, cobalt, energy, forage, gas exchange, gravel, growth performance, leaves, lignocellulose, magnesium, nutrient content, nutrient uptake, nutritional status, osmotic pressure, oxidative stress, photosynthesis, plant growth, potassium, sand, sandy clay soils, soil air, soil amendments, soil degradation, soil respiration, soil water, turgor, water holding capacity, water potential, water use efficiency
Soil water and nutrient status both are of major importance for the plant appearance and its growth performance. The objective of this research was therefore to study the effect of biochar (1.5% BC) and a biochar-compost mixture (1.5% BC + 1.5% Co) on the performance of Phragmites karka plants grown in a nutrient poor sandy clay (control, 50% sand 30% clay and 20% gravel) soil. The indicators of plant performance such as growth, lignocellulosic biomass, water relations, mineral nutrition status, leaf gas exchange, chlorophyll fluorescence parameters of P. karka, as well as soil respiration activity, were assessed. The sole amendment of BC led to higher growth rate and lignocellulosic biomass production in P. karka plants compared to the non-treated control. There was also significant increase in soil respiration with biochar treatments that stimulated microbial interaction. The increase in the water holding capacity after BC amendment caused a significant improvement in plant water status (water potential, osmotic potential, leaf turgidity) and plant ion content (K+, Mg++ and Ca++) leading to an increase of net photosynthesis but also a higher energy use efficiency of the Photosystem II. Additionally, the BC plants managed to avoid oxidative stress, improved water use efficiency (WUE) and decreased dark respiration. However, the amendment of a biochar-compost mixture (BC + Co) led to even better improvement of physiological parameters such as growth, leaf turgor, photosynthesis and nutrient content and soil gas exchange of P. karka. Our results suggested that BC and Co promote plant growth with respect to nutrient uptake, water balance, and efficiency of the photosynthetic system. In summary both soil amendments might open an opportunity for P. karka to sequester CO2 and to produce higher fodder, bio-active compounds and biomass for bio-energy on nutrient poor degraded soils.