Sains Malaysiana 49(12)(2020): 2891-2900

http://dx.doi.org/10.17576/jsm-2020-4912-02

Effect of Artificial Night Lighting on the Growth of Loose Head Lettuce in Hydroponic System

(Kesan Cahaya Malam Buatan terhadap Pertumbuhan Salad Loose Head dalam Sistem Hidroponik)

H.S. CHUA²*, LAI SIEW WEI¹, SIVAJOTHI PARAMASIVAM¹, T.T. GOH¹ & GEE CHIA CHEN¹

¹School of Electrical and Electronics Engineering, University of Wollongong Malaysia KDU, Glenmarie Campus, 40150 Shah Alam, Selangor Darul Ehsan, Malaysia

²School of Mechatronic Engineering, University of Wollongong Malaysia KDU, Glenmarie Campus, 40150 Shah Alam, Selangor Darul Ehsan, Malaysia

Received: 3 May 2020/Accepted: 28 July 2020

ABSTRACT

Supplemental LEDs lighting technology has been used as the promising lighting source in hydroponic cultures for sustainable production in urban agriculture. It could be the solution to address the growing concern about food safety, environmental impacts, bad weather, and efficient energy usage in agricultural production. In this study, the response of loose head lettuce toward the irradiance of the supplemental red-blue LED light with different power (Watt [W]) was investigated by comparing the treated lettuce with the lettuce cultured under only natural light. The lettuce plants were treated with red LED (640-660 nm) + blue LED (440-450 nm). The power output of the LEDs was specified to 3, 6, 9, 15, and 20 W. The lettuce plants were hydroponically cultured with 8 h red-blue LEDs light exposure (from 12 to 8 am) and 16 h without the red-blue LEDs light exposure (from 8 pm to 12 am) at average air temperatures of 31/28 ºC (day/night) for 50 days (7 weeks). On the harvesting day, the average shoot heights of the lettuce that was treated with 3, 6, 9, 15, 20 LEDs and natural light were 25.00, 24.75, 20.75, 19.88, 17.63, and 12.63 cm, respectively. The lettuce that was exposed to the 3 W LEDs had the highest shoot height compared to those that were exposed to LEDs with other power outputs. The average fresh weights of the lettuce that was treated with 3, 6, 9, 15, 20 W LEDs and natural light were 27.25, 24.75, 21.25, 19.88, 18.38, and 15.75 g, respectively. The results showed that the fresh weight of the lettuce that was irradiated with 3 W LED light was significantly higher compared to the lettuce that was exposed to LEDs with other power outputs. Hence, it can be concluded that supplementary LEDs lighting technology can be used as an alternative lighting source to improve the growth of lettuce in hydroponic systems. Moreover, the use of 3 W LEDs in hydroponic systems could yield a higher shoot weight and fresh weight.

Keywords: Hydroponic systems; LED light; loose head lettuce; urban agriculture

ABSTRAK

Teknologi pencahayaan LED tambahan telah digunakan sebagai punca pencahayaantambahan dalam pengkulturan hidroponik untuk pengeluaran lestari dalam pertanian bandar. Ia boleh menjadi penyelesaian kepada kebimbangan yang semakin meningkat berkenaan keselamatan makanan, kesan persekitaran, cuaca tidak baik dan penggunaan tenaga yang cekap dalam pengeluaran pertanian. Dalam kajian ini, tindak balas salad loose head terhadap pencahayaan LED merah-biru dengan kuasa yang berbeza (Watt [W]) telah dikaji dengan membandingkan salad terawat dengan salad terkultur di bawah cahaya semula jadi. Tumbuhan salad telah dirawat dengan LED merah (640-660 nm) + LED biru (440-450 nm). Output kuasa daripada LED telah dikelaskan kepada 3, 6, 9, 15, dan 20 W. Tumbuhan salad ini telah dikultur secara hidroponik dengan pendedahan kepada cahaya LED merah-biru selama 8 jam (dari 12 tengah malam ke 8 pagi) dan tanpa pendedahan kepada cahaya LED merah-biru selama 16 jam (dari 8 malam ke 12 tengah hari) pada purata suhu udara 31/28 ºC (siang/malam) selama 50 hari (7 minggu). Pada hari penuaian, purata ketinggian pucuk salad yang dirawat dengan 3, 6, 9, 20 W LED dan cahaya semula jadi masing-masing adalah 25.00. 24.75, 20.75, 19.88, 17.63 dan 12.63 cm. Salad yang terdedah dengan 3 W LED mempunyai ketinggian pucuk yang tertinggi berbanding dengan salad yang terdedah kepada LED dengan output kuasa yang lain. Purata berat segar salad yang dirawat dengan 3, 6, 9, 15, 20 W LED dan cahaya semula jadi masing-masing adalah 27.25, 24.75, 21.25, 19.88, 18.38 dan 15.75 g. Keputusan kajian menunjukkan berat segar salad yang dipancarkan dengan cahaya 3 W LED adalah lebih ketara nilai beratnya berbanding dengan salad yang terdedah kepada LED dengan output kuasa yang lain. Oleh itu, kajian inimerumuskan bahawa teknologi pencahayaan LED tambahan dapat digunakan sebagai salah satu sumber cahaya alternatif untuk penambahbaikan penumbuhan salad dalam sistem hidroponik. Selain itu, penggunaan 3 W LED dalam sistem hidroponik dapat meningkatkan hasil berat pucuk dan berat segar.

Kata kunci: Cahaya LED; pertanian bandar; salad loose head; sistem hidroponik

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*Corresponding author; email: hs.chua@kdu.edu.my