Md Asaduzzaman

Quality Improvement of Horticultural Crops through Hydroponics and Soilless Culture Under Greenhouse and Controlled Environment Agriculture

Hydroponics is a method of growing plants without soil through water or with medium to support the roots (perlite, rockwool, coco coir etc.), using complete nutrient solution (water + mineral nutrients), controlling the root zone condition (water, nutrients, oxygen, temperature). This is an alternative and managed culture technique that enables a more precise control of the growth conditions, which make it easier to study the variables, factors and parameters. The research uses this modern cultivation technique for improvement of growing conditions and quality of horticultural crops through following research themes.

Development of eco-friendly soilless substrate alternative to synthetic substrate
The availability of environmentally sound soilless substrate is scarce globally, including countries such as Bangladesh and Japan. While coconut substrate presents a promising alternative, its rising demand has driven up costs. To address this challenge, Dr. Asaduzzaman’s team is exploring various alternatives, such as balance of coconut substrate with perlite, as well as utilizing rice husk, river gravel, coarse sand and other locally available natural materials (Fig. 1).

Fig. 1 Production of netted melon in coconut substrate based soilless culture

Improvement of growing condition and use of plant growth stimulants
Plant growth and quality in horticultural crops can be enhanced through application of nanoparticles and bio-stimulants. This research focuses on investigating the efficacy of Fe-nanoparticles and various bio-stimulants in augmenting the growth and quality of tomato and sweet pepper cultivated in coco-nut substrate-based soilless systems (Fig. 2 – 3). Additionally, Dr. Asaduzzaman’s team is exploring the benefits of supplemental light emitting diodes (LED) lighting to boost growth and yield in sweet pepper, particularly during the winter season when photosynthetically active radiation (PAR) is low (Fig. 4).

Fig. 2 Foliar application of Fe-nanoparticles for the improvement of yield and quality of tomato in the naturally ventilated polyhouse (NVPH)

Fig. 3 Application of bio-stimulants on yield and quality of sweet pepper grown soilless culture

Fig. 4 Supplemental LED for the improvement of photosynthesis leading to increased yield of sweet pepper in the greenhouse

Specialty crop production through modification of environmental controls and hydroponic nutrients composition
Specialty crops offer potential dietary supplementation, intake of bioactive compounds and antioxidants improves human health. For instance, Non-Communicable Diseases (NCDs) due to dietary habits and the consumption of unsafe produce contaminated with pesticide residues and fertilizers are becoming a common problem in the world, including Bangladesh. Our research endeavors involve developing technologies for producing micronutrient-fortified leafy vegetables through hydroponic cultivation, as well as the production of low-potassium content fruits and vegetables through precise hydroponic nutrient management.

Investigation of autotoxicity in recycled hydroponics
Recycled hydroponics, increasingly popular for commercial produce, face autotoxicity, an intra-specific allelopathy caused by allelochemical accumulation (Fig. 5). Dr. Asaduzzaman’s team investigated this phenomenon in various crops and proposed measures such as activated charcoal adsorption, microbial degradation, auxin supplementation and electro-degradation of phenolic compounds. They have also studied optimal conditions for electro-degradation and tested methods such as amino acid supplementation and LED light variations to improve growth and yield in strawberries and lettuce. The team’s work continues to find effective solutions for challenges in recycled hydroponics for greenhouse and controlled environment agriculture.

Fig. 5 A schematic diagram showing the mode of action of phenolic acid and related compounds that affects plant growth and development during allelochemical stress/ autotoxicity under recycled hydroponics.