Estimating Nitrogen and Chlorophyll Status of Romaine Lettuce Using SPAD and at LEAF Readings

Nitrogen (N) is an essential nutrient for plant growth and development and is especially important in the production of high quality leafy green vegetables. In this experiment, leaf N concentration, chlorophyll concentration (Chl) and weight above fresh matter (AFM) of romaine lettuce (Lactuca sativa L. var. longifolia) were estimated by correlations between in situ SPAD and atLEAF readings. Lettuce was grown in high tunnels during 42 days and was irrigated at five nitrogen levels: 0, 4, 8, 12 and 16 mEq·L-1 of NO3-, based on the Steiner nutrient solution. The N concentration, Chl concentration and AFM were determined in the laboratory, while SPAD and atLEAF readings were measured in situ weekly. SPAD readings had high, positive and significant linear correlations with N (R2 = 0.90), Chl (R2 = 0.97) and AFM (R2 = 0.98); atLEAF readings had a similar linear correlation with N (R2 = 0.91), Chl (R2 = 0.92) and AFM (R2 = 0.97). Besides, SPAD and atLEAF readings had high, positive, and significant linear correlation (R2 = 0.96). Thus, SPAD and atLEAF meters can be used to non-destructively and accurately estimate the N status of lettuce, in a reliable and quick manner during the crop production cycle. In addition, atLEAF is currently more affordable than SPAD

Diversity and Genetic Structure of Scarlet Plume (Euphorbia fulgens), an Endemic Plant of Mexico

[EN] Euphorbia fulgens is an ornamental species cultivated in Europe and endemic to Mexico; its ecological, genetic, and evolutionary aspects are not known. The objectives of this study were to determine its distribution, describe the places it inhabits, and analyze the diversity and genetic structures of wild populations of E. fulgens. A bibliographic review of the herbarium specimens and a field evaluation were carried out to develop a potential distribution map based on a multi-criteria analysis of the climatic and topographic variables. Three populations (forty-five individuals) from pine–oak and cloud forests located in the Southern Sierra of Oaxaca were analyzed using ten microsatellite loci. The analysis was conducted using Arlequin v. 3.5, Mega v. 10, and Structure v. 2.3 programs. Eight loci were polymorphic, and a total of thirty-eight alleles were obtained. The average number of alleles per polymorphic locus was 4.6. The average heterozygosity of the three populations was high (Ho = 0.5483), and genetic differentiation between populations were low, with a high genetic flow, suggesting that it could be an ancestral population that became fragmented and was just beginning to differentiate genetically. The information generated on this restricted distribution species can be used in conservation programs pertaining to human activities that endanger the habitats where it is found.S

Cuantificación microlisimétrica del consumo de agua residual tratada en la nochebuena (Euphorbia pulcherrima Willd. ex Klotzsch)

En un cultivo de nochebuena en un invernadero instrumentado en Jiutepec, Morelos, se midió el consumo de agua residual tratada (ART) con microlisímetros de succión de macetas de polietileno de 15 cm de diámetro con sustratos de granulometría similar N, V y A, donde N = tierra de hoja/ tezontle/fibra de coco en proporción 60:20:20; V = tierra de hoja/tezontle/agrolita/fibra de coco (86:7:3.5:3.5); A = fibra de coco/tierra de hoja/agrolita (40:40:20), y el consumo de agua mediante microlisímetros de balance con sustrato N (BN); 11 de 22 variables presentaron diferencia significativa; BN tiene los valores más altos y V los menores; N es igual a A, para todas las variables analizadas. Las brácteas tienen diferencias en área, peso fresco y peso seco, sin diferencias en color L*, C* y h; las hojas no tienen diferencias en área ni en contenido de clorofila, y sí tienen en peso fresco y seco. Peso fresco y seco de raíz sin diferencias significativas. El sustrato A presentó mejores resultados agronómicos que N y V. El consumo de ART de la nochebuena puede ser afectado por tipo de planta y método de riego. En las semanas después del trasplante 2 (posterior al pinchado), 8, 9 y 10 (inicio de pigmentación), existen diferencias entre tratamiento y coincide con un periodo de disminución del consumo de ART. El microlisímetro de succión es una herramienta para cuantificar el consumo de ART en nochebuena

Comportamiento mecánico de frutos de papaya bajo compresión axial

The fruits of papaya (Carica papaya L.) are very susceptible to mechanical damage, which results in heavy losses in post-harvest. The aim of this study was to evaluate the mechanical behavior of papaya fruits in post-harvest, for which two experiments were conducted in the Experimental Field The Huasteca, INIFAP during the years 2011 and 2012. The variables evaluated were the strength and deformation required for the fruit to reach the elastic limit, biocedence and the breaking point. The compression was performed with a Instron Universal 4460. In the first experiment for ripening fruit treated with pre-harvest five combinations of fertilization, the treatment N-P-K-Cu-Zn, N-P-K-Ca-Zn, N-P-K-Fe-Zn reported increased resistance to force compression and was different to the treatment N-P-K-Mn-Zn (Tukey, p= .05). In the second experiment three cultivars were evaluated in two states of maturity, the fruits at physiological maturity were more resistant to attain the elastic limit (414 N) in relation to ripening (67 N), with statistical differences (Tukey, p= .05). The fruits of the hybrid PK 02 required more force to achieve the yield strength (298 N) with respect to the fruits of the variety Maradol roja (250 N) and the hybrid PK 03 (173 N), with differences (Tukey, p= .05). It is concluded that papaya fruits had different mechanical behavior depending on the nutritional management, the type of cultivar and maturityLos frutos de papaya (Caricapapaya L.) son muy susceptibles a los daños mecánicos, lo que repercute en fuertes pérdidas en poscosecha. El objetivo del presente trabajo fue evaluar el comportamiento mecánico de frutos de papaya en poscosecha, para lo cual se realizaron dos experimentos en el Campo Experimental Las Huastecas, INIFAP durante los años 2011 y 2012. Las variables evaluadas fueron la fuerza y la deformación requeridas por los frutos para alcanzar el límite elástico, el punto de biocedencia y el punto de ruptura. La compresión se realizó con un Instron Universal 4460. En el primer experimento se evaluaron frutos en madurez de consumo tratados en pre-cosecha con cinco combinaciones de fertilización; los tratamiento N-P-K-Cu-Zn, N-P-K-Ca-Zn, N-P-K y N-P-K-Fe-Zn registraron mayor resistencia a la fuerza de compresión y resultaron diferentes al tratamiento N-P-K-Mn-Zn (Tukey, p= 0.05). En el segundo experimento se evaluaron tres cultivares en dos estados de madurez; los frutos en madurez fisiológica fueron más resistentes para alcanzar el límite elástico (414 N), con relación a los frutos en madurez de consumo (67 N), con diferencias estadísticas (Tukey, p= 0.05). Los frutos del híbrido PK 02 requirieron mayor fuerza para alcanzar el límite elástico (298 N), con relación a los frutos de la variedad Maradol roja (250 N) y del híbrido PK 03 (173 N), con diferencias (Tukey, p= 0.05). Se concluye que los frutos de papaya tuvieron un comportamiento mecánico diferente, en función del manejo nutricional, del tipo de cultivar y del estado de madure

Agronomic practices and bio-stimulants for persian lime (Citrus latifolia Tan.) production in Mexico: BIOESTIMULANTS AND AGRONOMIC PRACTICES FOR THE PRODUCTION OF PERSIAN LIME

Objective: To evaluate biostimulants and cultural practices for floral induction in Persian lime (Citrus latifolia Tanaka) to obtain production in the Winter season, which when it is offered with the highest price in the market. Design/methodology/approach: During the period from July to September, biostimulants and cultural practices were applied to six-year-old trees as treatments as follows: 1. Pruning only, 2. Pruning + urea, 3. Pruning + urea + ringing, 4. Pruning + biofol® + ringing. Additionally, in September, two treatments more were included: 5. Pruning + calcium prohexadione, and 6. Pruning + Citomax®. The design used was randomized blocks with four repetitions. The experimental unit was a lime tree. Flowering, yield, physical-chemical quality and cost-benefit ratio were evaluated. Results: The outstanding effect of pruning and the effect of nitrogen were confirmed with the foliar application of granulated urea (6.0 Kg ha-1) during the period from July to September, obtaining an average yield of 23 t ha-1 during harvest from December to March, with a B/C 2.5 ratio. The quality of the fruit was kept within the NMX-FF-077-1996 Mexican standard. Pruning + Citomax® (cytokinins) applied in September showed a yield of 30 t ha-1, with a B/C 3.1 ratio. Findings/conclusions: Pruning + nitrogen, and pruning + cytokinins are suggested to induce flowering and produce Persian lime with the best winter yields.Objective: To evaluate biostimulants and cultural practices for floral induction in Persian lime (Citrus x latifolia Tanaka ex Q. Jiménez) to obtain production during the winter season, when the highest price in the market is offered with. Design/methodology/approach: From July to September period, biostimulants and cultural practices were applied to six-year-old trees with different treatments as follows: 1. Pruning only, 2. Pruning + urea, 3. Pruning + urea + ringing, 4. Pruning + biofol® + ringing. Additionally, during September, two more treatments were included: 5. Pruning + calcium prohexadione, and 6. Pruning + Citomax®. The design used was randomized blocks with four repetitions. The experimental unit was one lime tree. Flowering, yield, physical-chemical quality and cost-benefit ratio were evaluated. Results: The outstanding effect of pruning and the effect of nitrogen were confirmed with the foliar application of granulated urea (6.0 kg ha-1) during the period from July to September, obtaining an average yield of 23 t ha-1 during the harvest from December to March, with a B/C 2.5 ratio. The quality of the fruit was kept within the NMX-FF-077-1996 Mexican standard. September applied Pruning + Citomax® (cytokinins) showed a yield of 30 t ha-1, with a B/C 3.1 ratio. Findings/conclusions: Pruning + nitrogen, and pruning + cytokinins induce flowering and produce Persian lime with the best winter yields. Objective: To evaluate biostimulants and cultural practices for floral induction in Persian lime (Citrus x latifolia Tanaka ex Q. Jiménez) to obtain production during the winter season, when the highest price in the market is offered with. Design/methodology/approach: From July to September period, biostimulants and cultural practices were applied to six-year-old trees with different treatments as follows: 1. Pruning only, 2. Pruning + urea, 3. Pruning + urea + ringing, 4. Pruning + biofol® + ringing. Additionally, during September, two more treatments were included: 5. Pruning + calcium prohexadione, and 6. Pruning + Citomax®. The design used was randomized blocks with four repetitions. The experimental unit was one lime tree. Flowering, yield, physical-chemical quality and cost-benefit ratio were evaluated. Results: The outstanding effect of pruning and the effect of nitrogen were confirmed with the foliar application of granulated urea (6.0 kg ha-1) during the period from July to September, obtaining an average yield of 23 t ha-1 during the harvest from December to March, with a B/C 2.5 ratio. The quality of the fruit was kept within the NMX-FF-077-1996 Mexican standard. September applied Pruning + Citomax® (cytokinins) showed a yield of 30 t ha-1, with a B/C 3.1 ratio. Findings/conclusions: Pruning + nitrogen, and pruning + cytokinins induce flowering and produce Persian lime with the best winter yields

Daño mecánico por compresión en nardo (Polianthes tuberosa)

‘Perla’ tuberose (Polianthes tuberosa L.) sprigs were harvested with two open flower buds. They were submitted to compression treatments with 70, 140, and 210 Pa; subsequently, a 20% sucrose pulse solution treatment was applied alongside an Ethylbloc® treatment (1 bag with 0.014% active ingredient (1-MCP)) for 24 h. Some physiological changes were evaluated (CO2 and ethylene production indices, water consumption, and relative fresh weight) in the flower vase over the course of six days. Furthermore, two groups of tuberose sprigs were formed, compression not being applied to either. The first group received pulse solution whereas the second group did not, the latter being the control group. The tuberose sprigs showed increases in the respiration speed and ethylene production similar to climacteric flowers. The sprigs subjected to compression above 70 Pa showed between 31 and 47% greater respiration speed and between 26 and 29% greater ethylene production compared to the sprigs that received the control treatment. The percentage for the initial weight (7 and 11.5%) and water consumption (21 and 71%) was significantly greater in the flowers subjected to compression compared to the control group. It can be concluded then that the mechanical damage due to compression increasesSe cosecharon espigas de nardo (Polianthes tuberosa L.) ‘Perla’ con dos flores basales abiertas, fueron sometidas a tratamientos de compresión con 70, 140 y 210 Pa; posteriormente se les aplicó un tratamiento de solución pulso de sacarosa al 20% junto con un tratamiento de Ethylbloc® (1 bolsa con 0.014% de ingrediente activo (1-MCP)) por 24 h y se evaluaron algunos cambios fisiológicos (tasa de producción de CO2, etileno, consumo de agua y peso fresco relativo) en florero durante seis días. Adicionalmente se formaron dos grupos de espigas de nardo, en ambos no se aplicó la compresión, el primer grupo recibió solución pulso y el segundo no se aplicó solución pulso, este último fue considerado el testigo. Las espigas de nardo mostraron incrementos en la velocidad de respiración y producción de etileno similares a flores climatéricas. Las espigas sometidas a compresión superior a 70 Pa mostraron entre 31 y 47% mayor velocidad de respiración y entre 26 y 29% mayor producción de etileno comparadas con las que recibieron el tratamiento testigo. El porcentaje de peso inicial (7 y 11.5%) y consumo de agua (21 y 71%) fue significativamente mayor en las flores sometidas a compresión, con respecto al testigo. Se concluye que el daño mecánico por compresión incrementa la producción de etileno y velocidad de respiració

Propagación vegetativa y sexual de mayito (Zephyranthes fosteri Traub y Z. Lindleyana Herb.) (Amaryllidaceae)

Zephyranthes plants (Amaryllidaceae) are mostly wild and there is no information to enable its commercial production. Vegetative and sexual propagation of mayito plants (Zephyranthes fosteri Traub and Z. lindleyana Herb.) was evaluated using different induction methods for formation of bulblets from mother bulbs. Bulbs 2.1 to 2.3 cm in diameter were used, those were cut in six ways to induce shoots: 1) full bulb; 2) cross-sectional cut; 3) longitudinal cut; 4) cut in the shape of an “A” cut; 5) cross-sectional and longitudinal cut, and 6) cross-sectional and longitudinal cut splitting the scales of the basal sections into two parts. The bulbils ranged from 1.2 to 9.1, increasing as the number of cuts of the basal section increased. They were lower weight (0.208 g) and diameter (0.48 cm), when more bulblets were obtained by bulb. Z fosteri bulbils were the largest (0.186 g, 2.45 cm long, 4 mm diameter). Propagation by seeds allowed a larger amount of bulblets; on the other hand, bulbils were larger by vegetative multiplication.Las plantas de Zephyranthes  en su mayoría son silvestres y no se cuenta con información que permita la producción comercial. Se evaluó propagación por semilla y clonal de Z. fosteri, mediante inducción de bulbillos. Se usaron bulbos de 2.1 a 2.3 cm de diámetro, cortados en seis formas: 1) bulbo completo, 2) corte transversal, 3) longitudinal, 4) en forma de “A”, 5) transversal y longitudinal, 6)  transversal y longitudinal separando las escamas en dos grupos. En propagación sexual,  se utilizaron 400 semillas de Z. fosteri y  Z. lindleyana. Los bulbillos variaron de 1.2 a 9.1, aumentando conforme al número de cortes de la sección basal aumento; fueron de menor  peso  (0.208 g) y diámetro (0.48 cm), cuando se obtuvieron más bulbillos por bulbo. Los bulbillos de Z. fosteri fueron los  más grandes (0.186 g, 2.45 cm de longitud, 4 mm de diámetro). La propagación por semillas permitió mayor cantidad de bulbillos, pero con la vegetativa fueron grandes