O objetivo deste trabalho foi testar o efeito de hidrogel biodegradável (composto por 6% m/v de acrilamida e 1% m/v de carboximetilcelulose) e seus bionanocompósitos contendo diferentes concentrações ...de nanoargila (0-20% m/v) incorporados em um substrato de cultivo utilizado para germinação e desenvolvimento de mudas de alface (Lactuca sativa). Os experimentos foram conduzidos com um delineamento inteiramente casualizado. O primeiro experimento estudou doses crescentes de hidrogel incorporado no substrato. O segundo experimento avaliou os bionanocompósitos com crescentes concentrações de nanoargila. Os parâmetros analisados foram índice de velocidade de germinação, porcentagem de germinação, diâmetro do caule, massa fresca e seca, tamanho da raiz e alturas das partes aérea e total da planta. No primeiro experimento, notou-se que a aplicação de 5% foi a que apresentou os melhores resultados na germinação e o desenvolvimento do cultivo de alface. As aplicações dos bionanocompósitos demonstraram resultados positivos em todos os parâmetros analisados, causando também um melhor desenvolvimento do sistema radicular (segundo experimento). Sendo que os bionanocompósitos contendo 20% de nanoargila foram os mais promissores. Portanto, os hidrogéis e os bionanocompósitos otimizam a germinação da hortaliça Lactuca sativa, demonstrando ser um produto promissor para a aplicação na agricultura.
Corn is the second most cultivated crop in Brazil, the number-one country in pesticide consumption. Chemical control of weeds is performed using herbicides such as S-metolachlor with pre- and ...post-emergence action and thus the toxicity of herbicides constitutes a matter of great concern. The present investigation aimed to examine the effects of an S-metolachlor-based herbicide on Lactuca sativa L. (lettuce) and Zea mays L. (maize) utilizing various bioassays. The test solutions were prepared from commercial products containing the active ingredient. Seeds from the plant models were exposed in petri dishes and maintained under biochemical oxygen demand (BOD) at 24°C. Distilled water was negative and aluminium positive control. Macroscopic analyses (germination and growth) were conducted for both plant species, and microscopic analysis (cell cycle and chromosomal alterations) were performed for L. sativa root tip cells. Detrimental interference of S-metolachlor-based herbicide was noted with lettuce for all parameters tested reducing plant germination by over 50% and the germination speed by over 45% and showing a significant decrease in mitotic index, from 16.25% to 9,28% even on the lowest concentration tested. In maize, there was no significant interference in plant germination; however, speed of germination was significantly hampered, reaching a 51.22% reduction for the highest concentration tested. Data demonstrated that the herbicide was toxic as evidenced by its phyto- and cytotoxicity in L. sativa L. and Z. mays L.
Hydroponic systems provide a highly advantageous environment for cultivating green leafy vegetables. Among these advantages, there is a significant acceleration in harvest compared to conventional ...farming methods, the attainment of high yields, enhanced leaf coloring, increased nutritional content, and improved sweetness, all of which are crucial factors. However, a particular issue known as tip burn is encountered when cultivating, especially Yedikule (Romaine) type lettuce in hydroponic systems. This study investigates various calcium dosages applied via foliar spray to mitigate tip burn on Thespian and Suntred lettuce varieties (green and red Romaine mini types). Different calcium dosages were employed for both lettuce varieties. This experiment examined various parameters for both lettuce types, including plant height, root length, stem diameter, plant age, dry weight, root dry and fresh weight, macro and micronutrient content, dry matter, and total yield. The results indicate that combining foliar calcium and adequate ventilation effectively mitigates tipburn. This research emphasizes the significance of such a combined approach in preventing tip burn in hydroponically grown lettuce, specifically Thespian and Suntred varieties.
O reuso de efluentes domésticos brutos e tratados como fonte de água e nutrientes no cultivo hidropônico de hortaliças vem trazendo benefícios para os produtores rurais/urbanos, sociedade e o meio ...ambiente. Em virtude desses benefícios, esta pesquisa teve como objetivo avaliar o desempenho da produção de três cultivares da alface crespa (Verônica, Vanda e Thais) utilizando soluções nutritivas preparadas com efluente bruto, tratado e água subterrânea. A execução da mesma foi consolidada em ambiente protegido do Centro de Ciências Agrárias e Ambientais-CCAA da Universidade Estadual da Paraíba-UEPB Campus II, situada na zona rural do municipio de Lagoa Seca-PB. O delineamento experimental foi em blocos casualizados com parcelas subdivididas, a parcela experimental constituída por soluções nutritivas (S). S1 = solução de Furlani; S2 = efluente bruto; S3 = efluente bruto otimizado; S4 = água de subterrânea; S5 = água subterrânea otimizada; S6 = água residuária-UASB e S7 = água residuária-UASB otimizada e a subparcela com cultivares da alface crespa. As variáveis analisadas foram: número de folhas por planta, diâmetro caulinar, massa fresca e seca do caule e folhas, produção total e comercial. Independentemente da variável analisada, não se observou interação significativa entre soluções nutritivas e cultivares. Verificou-se que a solução de Furlani e a cultivar Vanda apresentaram o maior número de folhas por planta, a maior produção total e comercial, massa fresca e seca da folha e seca do caule.
Allelopathy of alien invasive plants (AIP) on plant germination performance is essential for their successful invasion. However, the allelopathy of AIP may be reformed or even strengthened under acid ...deposition. AIP in Asteraceae covers the uppermost number of AIP species at the family level presently in China. It is necessary to estimate the allelopathy of multiple Asteraceae AIP under acid deposition to address the mechanism driving their successful invasion, especially under acid deposition. However, research in this area is very restricted presently. This study purposes to estimate the allelopathy of four Asteraceae AIP, i.e.,
Conyza canadensis
L. Cronq.,
Erigeron annuus
(L.) Pers.,
Aster subulatus
Michx., and
Bidens pilosa
L., on germination performance of the cultivated Asteraceae plant species
Lactuca sativa
L. which is sensitive to allelochemicals under acid deposition with different levels of acidity. Of the four Asteraceae AIP,
C. canadensis
,
E. annuus
, and
B. pilosa
create noticeable allelopathy on germination performance of
L. sativa
. The allelopathy of the four Asteraceae AIP decreases in the following order:
E. annuus
,
C. canadensis
,
B. pilosa
, and
A. subulatus
. Acid deposition with a low level of acidity reduces the allelopathy of
C. canadensis
,
E. annuus
, and
B. pilosa
. Inversely, acid deposition with a high level of acidity elevates the allelopathy of
B. pilosa
. The progressively growing level of acid deposition with high acidity may facilitate the invasion process of
B. pilosa
via the improved level of allelopathy.
In the coming years, farmers will have to deal with growing crops under suboptimal conditions dictated by global climate changes. The application of plant biostimulants such as beneficial ...microorganisms and plant-derived protein hydrolysates (PHs) may represent an interesting approach for increasing crop tolerance to alkalinity and salinity. The current research aimed at elucidating the agronomical, physiological, and biochemical effects as well as the changes in mineral composition of greenhouse lettuce (
L.) either untreated or treated with a microbial-based biostimulant (Tablet) containing
and
alone or in combination with a PH. Plants were sprayed with PH at weekly intervals with a solution containing 2.5 ml L
of PH. Lettuce plants were grown in sand culture and supplied with three nutrient solutions: standard, saline (25 mM NaCl) or alkaline (10 mM NaHCO
+ 0.5 g l
CaCO
; pH 8.1). Salt stress triggered a decrease in fresh yield, biomass production, SPAD index, chlorophyll fluorescence, leaf mineral composition and increased leaf proline concentration, without altering antioxidant enzyme activities. The decrease in marketable yield and biomass production under alkali stress was not significant. Irrespective of nutrient solution, the application of Tablet and especially Tablet + PH increased fresh marketable yield, shoot and root dry weight. This was associated with an improvement in SPAD index,
/
ratio, CAT and GPX activities and a better nutritional status (higher P, K, and Fe and lower Na with NaCl and higher P and Fe with NaHCO
) via an increase of total root length and surface. The combination of microbial biostimulant with foliar application of PH synergistically increased the marketable fresh yield by 15.5 and 46.7% compared to the Tablet-treated and untreated plants, respectively. The improved crop performance of Tablet + PH application was attributed to a better root system architecture (higher total root length and surface), an improved chlorophyll synthesis and an increase in proline accumulation. Combined application of Tablet and PH could represent an effective strategy to minimize alkalinity and salinity stress in a sustainable way.
Effects of aqueous chlorine dioxide (ClO
2) treatment on enzymatic browning and shelf-life of fresh-cut asparagus lettuce (
Lactuca sativa L. var.
angustana) were investigated. Fresh-cut asparagus ...lettuce was treated at different concentrations (10, 40, and 100
mg
L
−1) for different times (5, 10, and 20
min). Following treatments, lettuce slices were stored at 4
°C for 14 d. The activities of polyphenol oxidase (PPO) and peroxidase (POD) in the lettuce were reduced by ClO
2, and degradation of color was also delayed. Thus ClO
2 concentration and treatment time were two significant factors affecting ClO
2 treatment on enzymatic browning of fresh-cut asparagus lettuce. From the microbiological and sensory quality perspectives, the treatment with 100
mg
L
−1 ClO
2 for 20
min could prolong the shelf-life to 14 d compared to 4 d for the control. These results indicated that ClO
2 treatment was a promising approach to inhibit enzymatic browning and prolong shelf-life of fresh-cut asparagus lettuce.
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