Production system and harvesting stage influence on nitrate content and quality of butterhead lettuce

Abstract

Leafy vegetables such as lettuce grown under different production systems may accumulate different concentrations of nitrate which may reach to the levels potentially toxic to humans. Moreover, nitrate accumulation varies in various plant parts and physiological age of the plant. Therefore, to determine the effect of production system and harvesting stage on nitrate accumulation and quality of butterhead lettuce, a study was conducted considering two lettuce production systems namely hydroponic and organic, and four different harvesting stages such as 35, 38, 41 and 44 days after transplanting (DAT). The experimental design was complete randomized design (CRD) with four replications. Hydroponic and organic systems performed similar in terms of yield, quality and nitrate content of butterhead lettuce. Delaying harvesting can not only increase yield but also can minimize nitrate accumulation and health hazard risk as well. Delay in harvesting stage may result in quality deterioration of lettuce and increased production cost. Thus, a compromise is necessary to consider 41 DAT as the optimum stage to harvest butterhead lettuce with significantly higher reduction of nitrate content in both outer adult leaf blades and young leaves of hydroponic lettuce. Fresh weight, firmness and color of butterhead lettuce at this stage were still acceptable.

Yield and Quality of Lettuce and Rocket Grown in Floating Culture System

“…Although lettuce is considered a nitrate accumulator and one of the major sources of nitrate intake in human diet (Di Gioia et al, 2013), the highest rate of N (200 mg L -1 ) implemented in the present study did not result in nitrate content higher than the limits allowed in E.U. This could be attributed to late harvesting (40 days after transplanting), since according to Yosoff et al (2015), harvest stage can affect nitrate content in butterhead lettuce leaves, with late harvests (41 days after transplanting) significantly reducing nitrate content. Moreover, growing period has a great effect on nitrate content in lettuce leaves due to seasonal differences in solar radiation and consequently in nitrate reductase activity (Petropoulos et al, 2011).…”

Nitrate Content in Minimally Processed Lettuce (Lactuca sativa L.) as Affected by Fluorescent Light Exposure During Storage

“…The extent of nitrate accumulation in lettuce is affected by different factors. An external factor such as the dosage of N-fertilizer application is the major factor determining the amount of nitrate accumulation in the leaves tissue [3]. Therefore, accumulation of nitrates in the leaves increased with nitrogen fertilizer supply [4].…”

“…The level of nitrate accumulation in lettuce can be differed in various plant parts. In butter head lettuce the higher content of nitrate is reported in the leaves [2,3]. Lettuce is commonly consumed raw as fresh cut, high accumulation of nitrate in the edible part of the plant causes nitrate toxicity leading to health problem.…”

Penerapan Hibrid Sistem Biofilter dan Hidroponik Sebagai Alternatif Pengolahan Limbah Pemukiman Low Income People

“…Pada umumnya, nitrat dikurangi atau disimpan di dalam vakuola tanaman. Namun, sebagian besar disimpan dalam vakuola sampai dilepaskan untuk pengurangan sitosol[21]. Daya absorbsi nitrat lebih tinggi pada selada yang ditanam di bawah sistem hidroponik dibandingkan dengan sistem organik.…”

“…Daya absorbsi nitrat lebih tinggi pada selada yang ditanam di bawah sistem hidroponik dibandingkan dengan sistem organik. Nitrat diabsorbsi diakumulasi pada berbagai bagian yaitu daun selada mengikuti urutan yaitu pada pelepah, daun-daun dewasa luar dan daun muda[21]. nitrat oleh mikroorganisme dalam sistem cukup tinggi, namun tanaman muda dapat mengimbangi kerja mikroorganisme dengan menyerap nitrat tersebut sebagai nutrisi dengan daya absorbsi yang sangat besar dan cepat sehingga nitrat yang terukur pada outlet hidroponik menjadi rendah.…”