Effects of biodegradable hydrogel incorporated in planting media on lettuce (Lactuca sativa sp.) growth and pesticide residues
2023
Carol, H.A. | Norida, M. | Norhayu, A. | Yusop, M.R.
Superabsorbent hydrogels are gels that were formed by chemical stabilization of hydrophilic polymers and have found its application in various sectors including mitigating the water scarcity in agriculture. Lettuce (Lactuca sativa sp.) is a popular crop, mainly cultivated using soilless media. The aim of this study is to determine the growth and yield of lettuce when hydrogel is incorporated into the planting media, as well as assessed the pesticide residues from the treatments. Three types of soilless plantings system were used (fertigation (F), hydroponic (H) and hydrogel+cocopeat (HG)) to plant butterhead lettuces. The experiment was conducted in a fully closed glasshouse. The experimental design used was randomized compete block design (RCBD) with 3 replicates and various growth and yield parameters were observed and taken. Chemical pesticide (a.i. imidacloprid and a.i chlorothalonil) were sprayed unto the crops and its residues were analyzed using gas-chromatography with electron capture detector (GC-ECD) at 1, 3, 5,7, 10 and 14 days after spraying (DAS). The result shows that lettuces planted in hydrogel incorporated in cocopeat has the overall best result in growth parameters, followed by fertigation and hydroponic system. The treatments given (control (T) and sprayed with imidacloprid (TZ)) have no significant effect on the lettuce's growth. As for the pesticide residues, on 5 DAS, most of the imidacloprid content has declined more than 70% and continues to do so until 14 DAS. Chlorothalonil on the other hand, requires at least 10 DAS for 70% decline across all planting systems. As a conclusion, hydrogel incorporated in the current soilless planting method can help to improve the overall lettuce's growth when paired with suitable pest and disease control method.
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