Estimation of Yield, Photosynthetic Rate, Biochemical, and Nutritional Content of Red Leaf Lettuce (Lactuca sativa L.) Grown in Organic Substrates.

Md Jahedur Rahman,Md Obyedul Kalam Azad,Md Hafizur Rahman,Ki-Young Choi,Most Tahera Naznin,Md Quamruzzaman,Md Jahirul Islam,Mohammed Saifur Rahman,Jasim Uddain,Md Dulal Sarkar

doi:10.3390/plants10061220

Abstract

This study aimed to evaluate the effect of organic substrates on the growth yield, photosynthetic response, and nutritional profile of red leaf lettuce grown in different compositions of cocopeat (CP), sawdust (SD), and rice husk (RH). The result showed that the properties of substrates were influenced variably by their mixing ratios. The highest water holding capacity and moisture content were found in CP, and it provided the preferable pH, electrical conductivity, bulk density, and air-filled porosity in association with other categories of the substrate. Cocopeat-based media provides ample microclimate conditions in the root region of plants and increased their height, number of leaves, and fresh biomass components. The utmost dry biomass of plant parts also remarkably increased in CP; L*, a*, and b* chromaticity of leaves remained unchanged. The maximum chlorophyll content was attained in CP substrate, except for chlorophyll a/b, which was higher in RH. The net photosynthetic rate (PN), transpiration rate (E), and nitrate in leaves were enhanced substantially in CP, while it was lower in SD. Biochemical compositions and nutrients in leaves were likewise stimulated under the culture of cocopeat-based media. Results indicate that cocopeat, sawdust, and rice husk are a possible substrates mixture in a volume ratio of 3:1:1, which would be a better choice in the cultivation of red leaf lettuce.

Highlights

Consumers are increasingly interested in balanced, fresh convenience foods, which has resulted in high demand for healthy ready-to-eat vegetables [1]
The experiment was conducted in an open field at Sher-e-Bangla Agricultural University (SAU), Dhaka, Bangladesh, from September to December 2018
Air-filled porosity at both 2 h and 5 h after drainage ranged from 15.24% and 17.64% in SD to 31.68% and 33.60% in RH, indicating that sawdust and cocopeat were the most efficient at retaining water in comparison to rice husks

Summary

Introduction

Consumers are increasingly interested in balanced, fresh convenience foods, which has resulted in high demand for healthy ready-to-eat vegetables [1]. Lettuce is a superior dietary fresh salad vegetable [2]. Because of the high concentrations of vitamins, minerals, dietary fiber, and antioxidant compounds, it is considered a health-promoting food [3]. Plants are grown in mineral substrates such as rock wool, vermiculite, perlite, zeolite, and ceramsite culture media. The growing medium provides mechanical support for plants and aids in the delivery of water, nutrients, and oxygen to the roots, enabling plants to grow and develop [6]. Substrate selection is one of the most important factors in soilless culture since it affects plant growth, development, and quality [7,8]

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Discussion

Conclusion