Sensitivity of lettuce cultivar Lucy Brown to pre-planting herbicide application

ABSTRACT Due to the low availability of herbicide active ingredients, the chemical weed management in lettuce crop is a challenge. The aim of this study was to evaluate the sensitivity of lettuce to the pre-planting application of the herbicides flumioxazin and trifluralin alone or in tank-mixture in lettuce, Lucy Brown cultivar. Two experiments were conducted. In experiment A, the soil was tilled before the herbicide application and it was tilled again before seedling transplanting. In experiment B, the soil was tilled just once before the herbicide application. The experimental design was in randomized blocks in a factorial scheme (3x3) +1 (2 factors with 3 levels and an additional control) with 4 replicates. We applied flumioxazin (120 g ha-1), trifluralin (450 g ha-1) and flumioxazin + trifluralin (120 + 450 g ha-1) in three different seasons before transplanting (0, 7 and 14 days). Lettuce productivity after trifluralin application (48.4 t ha-1) was higher than after flumioxazin application (16.8 t ha-1) in experiment A. In experiment B, flumioxazin decreased the number of lettuce leaves (25.6) at 14 DAT; no differences in lettuce productivity were verified, though. The herbicide trifluralin caused lower levels of phytotoxicity and was the most selective between the treatments when applied in the three seasons in both experiments.

Lettuce Growth Pattern Analysis Using U-Net Pre-Trained with Arabidopsis

To overcome the challenges related to food security, digital farming has been proposed, wherein the status of a plant using various sensors could be determined in real time. The high-throughput phenotyping platform (HTPP) and analysis with deep learning (DL) are increasingly being used but require a lot of resources. For botanists who have no prior knowledge of DL, the image analysis method is relatively easy to use. Hence, we aimed to explore a pre-trained Arabidopsis DL model to extract the projected area (PA) for lettuce growth pattern analysis. The accuracies of the extract PA of the lettuce cultivar “Nul-chung” with a pre-trained model was measured using the Jaccard Index, and the median value was 0.88 and 0.87 in two environments. Moreover, the growth pattern of green lettuce showed reproducible results in the same environment (p < 0.05). The pre-trained model successfully extracted the time-series PA of lettuce under two lighting conditions (p < 0.05), showing the potential application of a pre-trained DL model of target species in the study of traits in non-target species under various environmental conditions. Botanists and farmers would benefit from fewer challenges when applying up-to-date DL in crop analysis when few resources are available for image analysis of a target crop.

PERFORMANCE OF LETTUCE SUBMITTED TO THE ROCK DUST REMINERALIZER AND DOSES OF EFFICIENT MICROORGANISMS

The use of soil remineralizers with efficient microorganisms (EM) can represent an effective and sustainable alternative to improve the growth, development, and yield of cultivated plants. Thus, the present study aimed to evaluate the effect of different doses of EM, in the presence or absence of rock dust (RD), on the development of iceberg lettuce, cultivar Lucy Brown. The design used was completely randomized, arranged in a 2 x 5 factorial scheme, with four replications. The treatments consisted of the presence and absence of RD in the substrate composition, combined with five commercial product doses based on EM (0, 2, 4, 6, and 8 L ha-1). At 30 days after transplanting, root and stem length, head circumference, the number of leaves, stem diameter, leaf area, fresh matter of root, stem, leaf, and shoot, and dry matter of root, stem, leaf, and shoot were evaluated. There was an interaction between the factors for most variables of economic importance. The dose of 4.5 L ha-1 of the product based on EM, combined with PR, implied the best performance of iceberg lettuce under the studied cultivation conditions.

EFICIÊNCIA DE GONGOCOMPOSTOS OBTIDOS A PARTIR DE DIFERENTES RESÍDUOS VEGETAIS E SISTEMAS DE PRODUÇÃO NO DESENVOLVIMENTO DE MUDAS DE ALFACE

O uso do gongocomposto pode contribuir para suprir a crescente demanda por substratos destinados à produção de mudas de hortaliças em ambientes rurais e urbanos. Nesse contexto, objetivou-se com este trabalho verificar a eficiência dos gongocompostos obtidos em dois diferentes sistemas de produção, situados em regiões de ambientes distintos (estados do RJ e SP) e com a utilização de resíduos orgânicos e espécies de diplópodes diferentes entre si, na produção de mudas de alface. Inicialmente foi realizada uma minuciosa caracterização dos substratos avaliados, caracterizando as propriedades físicas, físico-químicas e químicas. O desempenho dos diferentes substratos na produção de mudas de alface foi avaliado por meio da semeadura de alface crespa cultivar Grand Rapids em bandejas de poliestireno expandido de 200 células. As mudas foram avaliadas aos 30 dias após a semeadura. Os gongocompostos produzidos no estado do RJ e SP apresentam diferenças em suas propriedades físicas, físico-químicas e químicas. No entanto, ambos produziram mudas de alface com qualidade semelhante, cujos parâmetros fitotécnicos foram superiores ao substrato comercial. Pode-se concluir que ambos os gongocompostos são eficientes como substrato na produção de mudas de alface, os quais podem ser produzidos em ambientes rurais e urbanos, atendendo à necessidade atual por insumos agrícolas sustentáveis. Palavras-chave: resíduos agrícolas e urbanos; diplópodes; gongocompostagem; substratos orgânicos; horticultura. Efficiency of millicomposts obtained from different vegetable residues and production systems in the development of lettuce seedlings ABSTRACT: The use of millicompost can contribute to the growing demand for substrates for vegetable seedling production in rural and urban environments. In this context, the objective of this work was to verify the efficiency of millicomposts obtained in two different production systems, located in regions of different environments (states of RJ and SP) and with the use of organic residues and different species of diplopods, in the production of lettuce seedlings. Initially, a thorough characterization of the evaluated substrates was performed, characterizing the physical, physicochemical and chemical properties. The performance of different substrates in the production of lettuce seedlings was evaluated by sowing crisp lettuce cultivar Grand Rapids in 200-cell expanded polystyrene trays. The seedlings were evaluated at 30 days after sowing. Millicomposts produced in the states of RJ and SP show differences in their physical, physicochemical and chemical properties. However, both produced similar quality lettuce seedlings, whose phytotechnical parameters were superior to the commercial substrate. It can be concluded that both millicomposts are efficient as a substrate in the production of lettuce seedlings, which can be produced in rural and urban environments, meeting the current need for sustainable agricultural inputs. Keywords: agricultural and urban wastes; diplopods; millicomposting; organic substrates; horticulture.

Identification and mapping of quantitative trait loci for resistance to Liriomyza trifolii in romaine lettuce cultivar ‘Valmaine’

Liriomyza trifolii (Diptera: Agromyzidae) is a leafminer that causes ruinous damage to many leafy vegetables including lettuce (Lactuca sativa L.) by stippling and tunneling the leaves. In this study, a population of 125 F3 families was developed from the intraspecific cross of ‘Valmaine’ (resistant) and ‘Okeechobee’ (susceptible) romaine cultivars for inheritance analysis and molecular mapping of the resistance loci controlling stippling damage. The experiments were conducted in an insectarium (controlled environment). Stippling damage proved to be heritable because the broad-sense heritability (H2) was 0.58. A segregation analysis suggested that a single dominant allele, Sd1 locus, controls resistance against L. trifolii. Furthermore, a quantitative trait loci (QTL) analysis identified one novel QTL, named Stippling on LG5 (qSTP5), flanked by two SNPs that were mapped to a 5.2 cM (8.5 Mb region) interval, explaining over 13% of the total phenotypic variance. Desirable allele for resistance to L. trifolii was derived from resistant cultivar Valmaine. Identification of SNPs closely linked to the QTL responsible for L. trifolii resistance should facilitate plant breeders to develop resistant romaine lettuce cultivars.

POTASSIUM FERTIRRIGATION ON ICEBERG LETTUCE

The aim of this work was to evaluate the influence of potassium doses, being applied in fertigation on iceberg lettuce cultivar “Lucy Brown” in Typic Hapludox. The experimental design was in randomized blocks, consisting of six doses of K2O (0; 15, 30, 45, 60, 75 kg ha-1) and four blocks. The treatments were applied in six periods: 15, 21, 28, 34, 39, and 43 days after transplantation seedlings, using potassium chloride as a source of K2O. The variables analyzed were: total fresh mass, fresh head mass, head circumference, number of inner leaves, number of outer leaves, total number of leaves, total yield and commercial yield. Data were subjected to analysis of variance and means compared by regression models. Thus, we can conclude that the K2O doses that provides the highest value of the variables is 75 kg ha-1, with the exception of the number of internal leaves that do not have a significant effect.

No-tillage curly lettuce cultivated under different spacings

ABSTRACT The use of appropriate cultural practices is important for the sustainability of the production system. This study aims to evaluate the agronomic performance of lettuce cultivar ‘Mônica’, during two crop cycles, at the Instituto Federal Catarinense, Campus of Concórdia, SC, Brazil. Two experiments were conducted in the field, arranged in randomized block design, in a 3 x 2 factorial scheme, evaluating the effects of three spacings (0.20 × 0.20, 0.25 × 0.25 and 0.30 × 0.30 m), associated with two planting systems (conventional and no-tillage with millet), with four repetitions in the first cycle and five in the second. At 39 and 44 days after transplanting, six plants were harvested in the first and in the second cycles, respectively. Soil temperature, fresh and dry mass of the spontaneous plants, dry mass of roots, plant diameter, number of marketable leaves, fresh and dry mass of the plants were evaluated. Lettuce cultivated under no-tillage at larger spacings resulted in higher yield per plant, but higher yield per area was observed at smaller spacing. No-tillage reduced spontaneous plants and soil temperature in the West of Santa Catarina.

Effects of Nutrient Composition and Lettuce Cultivar on Crop Production in Hydroponic Culture

A greenhouse research study was conducted at Eastern New Mexico University, Portales, NM, USA, in 2019 to examine the effects of different nutrient solutions on the growth and weight of two lettuce cultivars grown in a floating hydroponic system. Two lettuce cultivars, Buttercrunch and Black Seeded Simpson, were subjected to one of four different nutrient concentrations of N, K and Ca at 150, 100, and 150 ppm (N1), 210, 235, and 200 ppm (N2), 250, 300 and 250 ppm (N3), and 300, 350, and 350 ppm (N4), respectively. The Buttercrunch cultivar and N3 treatment proved significantly more productive than the other cultivar/treatment combinations. The greatest fresh weights were recorded in the N3 nutrient solution, 115.33 and 93.17 g/plant for Buttercrunch and Black Seeded Simpson, respectively. Buttercrunch had the greatest fresh weight, leaf number, and leaf and root length in all nutrient solutions. The nitrogen content of the solutions showed a significant positive relationship with chlorophyll content for both cultivars. It is expected that the development of a cheap and easy-to-use hydroponic system will help growers produce high-quality organic vegetables including lettuce.