Document Type : Research paper
Authors
1
Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
2
Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Seed Bank Unit, Natural History Museum, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Centre of Insects Systematics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
3
Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Abstract
It is predicted that the average world temperature will rise by 1.5 ºC in the next few decades, which may adversely affect vegetable productivity and global food security. The present study aimed to identify lettuce genotype(s) that are tolerant of heat stress so that they may be good candidates for future breeding programs to develop heatstress-tolerant lettuce cultivars. While using a complete randomized design with three replicates, we evaluated the performance of eight lettuce genotypes using a hydroponic system under non-stress (controlled) and heat stress (high temperature) environmental treatments. The effects of environmental treatments on the morphophysiological and agronomic characteristics of the genotypes were assessed. Ten traits were recorded after harvest, i.e., the number of leaves, plant height, root length, yield, fresh root weight, plant weight, leaf area, leaf width, leaf length, and chlorophyll contents. In general, lettuce genotypes cultivated under heat stress exhibited decreased performance in most traits compared to the non-stress treatment group. The yield of SAL092, SAL093, SAL094, SAL095, SAL096, SAL097, and SAL099 decreased by 65.8%, 66.4%, 65%, 28.2%, 40.6%, 76.3%, and 73.1%, respectively, under heat stress. In contrast, SAL098 grown under non-stress conditions showed higher yield, leaf count, root length, plant weight, and plant height by 0.1%, 15.2%, 0.9%, 4%, and 27%, respectively, compared to non-stress conditions. In addition, during heat stress, every trait exhibited a positive correlation with yield, except leaf width, suggesting that productive attributes are crucial for enhancing yield under high-temperature conditions. SAL095 and SAL098 exhibited effective adaptive mechanisms and may be regarded as potential heat-tolerant genotypes for future breeding programs and developing heat-tolerant cultivars and high yields.
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