Greenhouse Assays with Lactuca sativa for Testing Sewage Sludge-Based Soil Amendments

Sustainable agriculture practices within the guidelines of nutrient recycling and the circular economy must be increasingly promoted. This work aims to evaluate the performance of dried sewage sludge (DSS), green liquor dregs mixed with sewage sludge (DSSA), raw sewage sludge, and commercial organic fertilizer control, using a short-term agronomic assessment with lettuce crop (Lactuca sativa) in greenhouse conditions. Different application rates based on the nitrogen content were tested for each soil amendment: 0, 85, 170, and 225 kg N/ha (treatments T0, T1, T2, and T3, respectively). DSS and DSSA resulted in fresh lettuce productivities 1.3 and 3.2 times higher in T3 than in T0, respectively. The ideal N content in lettuce leaves was reached for all materials and treatments, with the highest values obtained for DSS (2.88–3.33% from T1 to T3). Lettuce produced in soils amended with DSS and DSSA showed also ideal levels of Ca. Overall, the performance of sludge-based products was similar to commercial fertilizer, without impairing the nutritional balance of the crop and the soil.

Nutrient Availability for Lactuca sativa Cultivated in an Amended Peatland: An Ionic Exchange Study

Few conservation strategies have been applied to cultivated peatland. This field study over one growth cycle of Lactuca sativa examined the effect of plant-based, high-C/N-ratio amendments in a real farming situation on peatland. Plant Root Simulator (PRS®) probes were used directly in the field to assess the impacts of incorporating Miscanthus x giganteus straw and Salix miyabeana chips on nutrient availability for lettuce. The results showed that lettuce yield decreased by 35% in the miscanthus straw treatment and by 14% in the willow chip treatment. In addition, the nitrogen flux rate was severely reduced during crop growth (75% reduction) and the plant N uptake index was much lower in the amended treatments than in the control. The phosphorus supply rate was also significantly lower (24% reduction) in the willow treatment. The influence of sampling zone was significant as well, with most macro-nutrients being depleted in the root zone and most micro-nutrients being mobilized. Additional work is needed to optimize the proposed conservation strategy and investigate the effects of consecutive years of soil amendment on different vegetable crops and in different types of cultivated peatlands to confirm and generalize the findings of this study. Future field studies should also explore the long-term carbon dynamics under plant-based, high-C/N-ratio amendments to determine if they can offset annual C losses.

Evaluasi Penerapan Sistem Hidroponik Tenaga Surya Berbasis Iot Untuk Peningkatan Produktivitas Hasil Pertanian Tanaman Hortikultura

Pertanian menjadi sektor penting bagi masyarakat Indonesia sebagai tumpuan pemenuhan kebutuhan pangan. Kebutuhan pangan akan selalu meningkat dengan seiring pertambahan jumlah penduduk. Berdasarkan data Badan Pusat Statistik dan Direktorat Jendral Hortikultura tahun 2018 sampai 2019, produktivitas nasional tanaman hortikultura pada beberapa jenis sayuran rata-rata negatif dan mengalami penurunan. Inovasi melalui metode smart hidroponik Internet of Thing (IoT) dan tenaga surya dapat diterapkan dalam usaha meningkatkan produktivitas tanaman dan profitabilitas produksi. Penelitian ini bertujuan meningkatkan produktivitas hasil budidaya pertanian berbasis IoT dibandingkan dengan budidaya pertanian tradisional yang dilakukan saat ini. Beberapa jenis tanaman yang tanam dalam penelitian ini adalah kangkung (Ipomea aquatica), caisim (Brassica chinensis var. parachinensis), selada keriting (Lactuca sativa), dan pakcoy (Brassica rapa subsp. chinensis). Dua perlakuan yang diberikan Budidaya sayuran pada media tanah yang terproteksi oleh greenhouse dan budidaya sayuran pada media hidroponik berbasis tenaga surya yang terproteksi oleh greenhouse berteknologi 4.0. Percobaan dilakukan dengan menggunakan rancangan acak lengkap (RAL) dengan 3 ulangan. Tinggi tanaman, diameter batang, jumlah daun, panjang daun, dan bobot tanaman dengan budidaya pertanian berbasis tenaga surya yang terproteksi oleh greenhouse berteknologi 4.0 menghasilkan pertumbuhan yang lebih besar dibandingkan dengan tanaman yang ditanam di tanah.

Phytotoxicity of plant extracts of Vismia japurensis cultivated in vivo and in vitro

Plants that produce secondary metabolites with allelopathic activity or phytotoxicity can be biotechnologically important, serving as sources of allelochemicals, and thus contributing to the agroindustrial sector. Vismia japurensis (Hypericaceae) is an Amazonian species that grows in clumps called vismiais, from which most other plants are absent. Accordingly, the objective of this study was to identify possible phytotoxicity effects of hexane and methanol extracts of Vismia japurensis leaves and branches in vivo and from seedlings grown in vitro on Lactuca sativa. In addition, fresh and dry leaves were assayed by the sandwich method in order to determine their ability to release allelochemicals. The hexanic extract from in vitro seedlings reduced germination by 10%, while the methanol extract produced a 16% reduction in germination speed. Root growth of Lactuca sativa was inhibited by 64.7% when subjected to hexane leaf extract, by 39.3% under the influence of hexane branch extract, and by 96.09% for in vitro seedling hexanic extract. When analysed by thin layer chromatography and 1H nuclear magnetic resonance, extracts showed evidence of terpenes, anthraquinones and flavonoids, with greater intensity of signals in the aromatic region of in vitro seedling hexanic extract. Clearly, Vismia japurensis has a high biotechnological potential in terms of the production of substances of low polarity with capacity to interfere in plant development.

A Physiological behavior and tolerance of Lactuca sativa to lead nitrate and silver nitrate heavy metals

This study goal to evaluate the effects of different concentrations of lead (Pb) and silver (Ag) on germination, initial growth and anatomical alterations of Lactuca sativa L. Plants use various mechanisms to reduce the impacts caused by anthropic action, such as xenobiotic elements of soils and water contaminated by heavy metals. These metals were supplied as lead nitrate and silver nitrate and the following treatments were established: control for both metals, maximum dose of heavy metals, for arable soils, allowed by the National Council of the Environment (Ag = 25 mg. Kg-1, Pb = 180 mg. Kg-1), double (Ag = 50 mg. Kg-1, Pb = 360 mg. Kg-1) and triple (Ag = 75 mg. Kg-1, Pb = 540 mg. Kg -1) of this dosage. Vigor and germination tests of the seeds and possible anatomical changes in the leaves and roots of lettuce plants were performed. The species showed a high capacity to germinate under Pb and Ag stress, and the germination was never completely inhibited; however, the germination decreased with increasing Pb concentrations, but not under Ag stress. The use of increasing doses of metals reduced seed vigor and increased chlorophyll content. An increase in biomass was also observed in plants from treatments submitted to Pb. The phytotoxic effects of metals were more pronounced at 15 days after sowing. Anatomically, L. sativa was influenced by metal concentrations, and had a reduction of up to 79.9% in root epidermis thickness at the highest Pb concentration, although some structures did not suffer significant changes. The results suggest that L. sativa presents tolerance to high concentrations of heavy metals, showing possible mechanisms to overcome the stress caused by these metals. In this research lettuce possibly used the mechanism of exclusion of metals retaining Pb and Ag in the roots preserving the photosynthetic apparatus in the aerial part of the plants. In general, the chemical element Pb was more toxic than Ag, in these experimental conditions.