Greater Stem Diameter Research Articles

Below-Plant Mirrors Improve Serianthes Seedling Survival and Growth in Shade

Recruitment failures of Serianthes nelsonii are among the threats to this species’ recovery, yet adaptive management research to understand the causes of seedling mortality is lacking. Insufficient available light in the in situ forest floor is one factor that may be involved, and below-plant reflection of incident light may improve seedling survival. Mirrors were placed beneath S. nelsonii, Serianthes grandiflora, and Serianthes kanehirae seedlings in container nursery conditions and S. grandiflora seedlings in a closed-canopy forest to determine the influence of the additional reflected light on seedling survival and growth. Below-plant mirrors increased nursery seedling survival for S. nelsonii and S. kanehirae, with 75% combined survival without mirrors and 88% combined survival with mirrors. Below-plant mirrors increased stem height by 51% for the three species, with greater stem diameter and ending leaf number also occurring for plants with mirrors. Below-plant mirrors increased S. grandiflora seedling survival to 161% and longevity to 236% compared to plants without mirrors under forest cover. The plants receiving mirrors also increased by 175% in height, 60% in stem diameter, and 117% in leaf number compared to the plants without mirrors. These findings indicate that passive solar engineering by exploiting below-plant light reflection may be used as a Serianthes conservation protocol to improve seedling survival and growth under shaded conditions.

Growth and Biomass Distribution in Cocoa Varieties under Different Nitrogen Regimes

Among the 17 vital plant nutrients, nitrogen (N) is crucial in crop production. It extensively enhances the growth and biomass production of plants by improving photosynthesis and protein synthesis. To study the impact of three different N levels (40, 80, and 120 ppm) on the growth and biomass production of eight cocoa varieties, a hydroponic experiment was carried out at ICAR-CPCRI, Regional Station, Vittal. The results showed that increasing N concentration significantly boosted growth and biomass production. Among the different varieties, VTLCH-1 exhibited the highest plant height, maximum number of leaves, greater stem diameter, and the highest total fresh biomass with the application of 120 ppm nitrogen. Biomass partitioning analysis revealed that higher N levels increased leaf and stem biomass while reducing root biomass, leading to a higher shoot-to-root ratio. This indicates that N application influences the biomass production and distribution in the plant.

Polyploidization Impact on Plant Architecture of Watermelon (Citrullus lanatus)

Plant architecture includes traits such as plant height, stem diameter, and branching pattern, which have significant impacts on yield and fruit quality. Polyploidization can bring changes in plant architectural traits in different crops along with other agronomic and biochemical attributes; however, the specific physiological and biochemical mechanisms are still unclear. In this study, we utilized five watermelon lines: ‘91E7’, ‘Zhengzhou No. 3’, ‘Fanzu No. 1’, ‘Shenlong’, and ‘Houlv’, along with their corresponding autopolyploid derivatives (diploid, autotriploid, and autotetraploid) to compare plant architecture differences in different polyploidy watermelon plants. The results showed that the growth habits of diploid, triploid, and tetraploid watermelon plants were noticeably different. Triploid and tetraploid watermelon plants had greater stem diameters and larger leaf sizes. The leaf angle was also larger in polyploid watermelons than in their diploid ancestor lines. Although vine length was significantly higher in diploid watermelon, there was no significant difference in node number, indicating that the short vine length was due to the short internodal length. The major differences between diploid and polyploid watermelon plants were found in the branching pattern, as diploid watermelon lines have more branching compared to their polyploid sister lines. Furthermore, we examined the phytohormone content of diploid, triploid, and tetraploid ‘Fanzu No. 1’. The reasons for the selection of this material are its robust growth and profuse branching habit, which cause visible differences among the ploidy levels. Hormone analysis showed distinct variations in abscisic acid in the nodal and stem regions, gibberellin in the auxiliary bud regions, and brassinosteroids in the apical meristematic regions. The correlation coefficient also strongly correlated these hormones with architecture-related traits. Our findings indicated that gibberellin, ABA, and brassinosteroids might be associated with variations in plant architectural traits like branching, vine length, internodal length, stem thickness, and leaf angle among different ploidy levels of watermelon. The exogenous application of GA3 showed a positive effect on branching, whereas ABA showed a negative effect on branching. The application of brassinosteroid at the apical meristem demonstrated its effect on leaf angle, leaf size, and internodal length. The results of this study can provide a theoretical reference and valuable insights into the link between plant architecture and ploidy levels.

Chestnut blight (Cryphonectria parasitica (Murr.) Barr) disease incidence and its effect on the morphological and anatomical features of Castanea sativa trees

AbstractSweet chestnut (Castanea sativa) is an ecologically and economically valuable tree species worldwide. Various pathogens, both endemic or introduced, cause severe damage or death to chestnut trees. Chestnut blight, caused by the fungus Cryphonectria parasitica, is one of the most devastating plant diseases known which influences chestnut trees in all major cultivation regions. The work presented here aimed to investigate how the incidence of chestnut blight varied between trees growing at two altitudes (200–400 m vs. 400–600 m) and to determine the impact of chestnut blight on tree‐ring width, morphology and anatomy of C. sativa trees. The incidence of C. parasitica infections was greater at 200–400 m than at 400–600 m. Greater stem diameters were found at 200–400 m than at 400–600 m. There were no differences in stem diameters and heights, however, between healthy and C. parasitica infected chestnut trees. The anatomical characteristics of wood were also compared between healthy and C. parasitica‐infected chestnut trees. Fibre cell traits (length/width, lumen width, lumen area) were higher in healthy trees than in C. parasitica‐diseased trees. Vessel diameters were greater in infected compared with healthy trees. Tree ring widths and wood anatomical characteristics therefore were significantly influenced by C. parasitica infections.

Desempenho agronômico do amaranto no semiárido em função do arranjo espacial

ABSTRACT The potential effects of climate change on agricultural yields require a greater understanding of cropping systems that include underutilized agricultural crops with greater adaptive capacity to water and thermal stresses, such as grain amaranth (Amaranthus sp.). The aim of this work was to evaluate how the planting arrangement affects the agronomic performance of grain amaranth BRS Alegria (Amaranthus cruentus L.) grown under semi-arid conditions. One experiment was carried out in a complete randomized block design with five repetitions in a 2 x 3 factorial scheme (two row spacings - 30 and 40 cm; three plant spacings - 20; 30 and 40 cm); in two crop years, 2019 and 2020 in the municipality of Pentecoste, CE, Brazil. The evaluated characteristics were plant height, stem diameter, number of leaves, fresh matter yield, aboveground biomass yield (dry weight), grain yield, thousand-grain weight, lipid content, and harvest and lodging indexes. The evaluated planting arrangements did not affect plant height and number of leaves, but did affect stem diameter and lodging index, as the 40 cm plant spacing resulted in greater stem diameter and lower lodging index. Narrow spacing (30 x 20 cm) resulted in a higher lodging index but also resulted in a higher fresh matter yield, aboveground biomass, grain yield, harvest index and lipid content. Thousand-grain weight was greater at 30 x 40 cm spacing. The 30 x 20 cm arrangement can be recommended for the cultivation of grain amaranth in the study area.

Hydrological and erosion responses of steep spoil heaps to taproot and fibrous root grasses under simulated rainfalls

Spoil heaps, resulting from excavation and backfilling activities at construction sites, are one of the most important risk sources of soil erosion, threatening local ecosystems and even leading to geological disasters. However, after revegetation, spoil heaps can be transformed into available land resources such as cultivated land and forest land. Previous studies have reported the runoff and sediment reduction benefits of different vegetation measures on spoil heaps, while little information has been documented about what differences in the taproot and fibrous root grasses were transferred into the differences in hydrological and erosion processes. This study compared the effects of taproot (Artemisia gmelinii (A. gmelinii)) and fibrous root (Cynodon dactylon (C. dactylon)) grasses on soil erosion and runoff production processes and the reduction benefits of spoil heaps with silt loam soil. A series of rainfall events at three intensities (0.8, 1.2, and 1.8 mm min−1) were simulated on runoff plots (length of 3.0 m and width of 1.0 m) under treatments of A. gmelinii, C. dactylon, and bare soil (BS, as control) (each treatment was replicated), and the initial runoff time (IRT), saturated hydraulic conductivity, runoff rate (RR), flow velocity, and soil loss rate (SLR) were measured. The results showed that grasses delayed the IRTs on spoil heaps by 0.69–12.96 min compared BS, and the delay effects were more significant for fibrous root grass than for taproot grass. The soil loss reduction benefits (91.1 %) of the two kinds of grass were approximately 2.2 times greater than those of runoff volume reduction (42.1 %), and shear stress could be used to predict the soil loss rate following power functions (R2 = 0.72–0.85) for the grass-covered plots. The taproot grass exhibited a higher erosion reduction than fibrous root grass and is thus preferred to control the soil erosion of spoil heaps. Taproot grass has a greater stem diameter and can insert deeper into spoil heaps to consolidate the soil particles, which can improve roughness and hydraulic resistance, thereby producing a lower effective hydraulic shear stress that is directly exerted on soil particles. This study enhances the understanding of different grasses on the water erosion process and mechanism of spoil heaps and provides scientific guidance for selecting erosion control practices.

Effect of the seed weight on the growth of young avocado rootstock seedlings

The cultivation of avocado cv. Hass (Persea americana Miller) in Colombia has grown in recent years. Among the country's challenges is to increase the orchards' productivity by guaranteeing grafts plants the best agronomic, genetic, and phytosanitary parameters. This work aims to evaluate for 90 days (nursery phase) the growth and development of avocado rootstocks originated from seeds with different weight ranges. A completely randomized experimental design was carried out, with treatments consisting in four Creole avocado seed weights (40-60 g, 60-80 g, 80-100 g, and over 100 g). In general, seeds greater than 80 g had the best germination percentage (over 70 %), a greater plant height, and a greater stem diameter in each of the evaluated periods. The seeds greater than 100 g presented the emergence of multiple stems at 30 days after transplanting; this fact was related to the size and reserves of the seed. The highest accumulated dry matter in stems, leaves, and total plant (without seeds) (cotyledons) were present in treatments with seeds above 80 g. These plants showed higher germination, significant more accumulation of biomass and greater vigor, which could shorten the nursery time while guaranteeing the quality of the material influenced by improved growth and seedling survival.

What drives patchiness in palmiet wetlands?

Wetland communities are shaped by high levels of stress, disturbance and competition. Using South African palmiet wetlands as a case study (Prionium serratum dominated valley-bottom wetlands), we explore whether autogenic or allogenic succession is the dominant process driving community dynamics in valley-bottom wetlands in drylands. Several wetland rehabilitation programmes in South Africa use the dominant wetland species palmiet (P. serratum) as a pioneer to facilitate recolonization. However research is needed on palmiet wetland dynamics and formation to guide these restoration efforts. We explore vegetation patterns by analyzing which environmental parameters drive dominance of palmiet, resulting in the characteristic patchiness of palmiet wetlands, and which plant functional traits account for this. In 20 plots from three palmiet wetlands distributed across the Cape Floristic Region of South Africa, key soil, groundwater and vegetation parameters, as well as community composition were measured. Twenty-two dominant species were selected and 13 functional traits measured. Soil pH and relative groundwater depth were the main environmental parameters driving community assembly in palmiet wetlands. Palmiet-dominated communities were characterized by greater stem diameter, leaf length–width ratio, leaf area and cellulose and lignin concentration compared to fynbos communities. These traits suggest adaptations to disturbances such as fires (thicker stems) and floods (long, thin leaves, flexible shoots and thicker stems). We propose three hypotheses of palmiet wetland development which shed light on palmiet wetland restoration and highlight gaps for future research.

Soil Effects on Stem Growth and Wood Anatomy of Tamboril Are Mediated by Tree Age

Soil influences the growth of trees and the characteristics of the wood; but could this influence change during the ontogeny of trees? To answer this question, we analyzed the wood anatomy of 9-year-old trees and 2-year-old saplings of Enterolobium contortisiliquum, known as “tamboril”, growing in eutrophic and oligotrophic soil in the Brazilian Cerrado, and assessed the effect of age on plant–soil relationship. Sapwood samples were collected from the main stem, anatomical sections were prepared in the lab, and 12 anatomical wood traits were measured. Individuals in eutrophic soil had greater stem diameter and height than those in oligotrophic soil. Trees in eutrophic soil had vessel-associated parenchyma cells with abundant storage compounds. Fibers walls were 47% thicker and intervessel pits diameter were 14% larger in trees of eutrophic soil. A greater proportion of solitary vessels (74%) was observed in trees rather than in saplings (50%). The secondary xylem of trees was mainly formed by fibers (63%) whereas in saplings it was mainly formed by storage tissue (64%). Our study provides evidence that the influence of soil conditions on tree growth reflects variations in wood anatomical features. No significant response to soil type was observed in saplings, thus demonstrating that the relationship between soil type and wood growth is mediated by tree age. These findings help to develop reliable reforestation strategies in tropical ecosystems characterized by different levels of soil fertility.

INITIAL DEVELOPMENT OF GABIROBA (Campomanesia adamantium) ACCORDING TO FERTILIZATION WITH NITROGEN AND PHOSPHORUS

Campomanesia adamantium (Cambess.) Berg O. is a native of Savanna, popularly known as gabiroba, guavira, or gabiroba-do-campo, and has many uses, with its fruit being consumed fresh or processed. This study aimed to evaluate different doses of phosphorus and nitrogen in the initial development of gabiroba (Campomanesia adamantium) cultivated in pots. Five doses of phosphorus (0, 100, 200, 300, and 400kg ha-1 of P2O5) and three doses of nitrogen (0, 100, and 200 kg ha-1of N) were tested. The experimental design used was completely randomized in a 5x3 factorial scheme with six replications. The evaluations were carried out 120 days after plant emergence, and the variables analyzed were stem diameter, plant height, and number of leaves. Data were subjected to analysis of variance and F-test. The means were compared by the Tukey test at p0.05. Regression analyzes were adjusted for phosphorus doses. The gabiroba responds significantly to the addition of phosphorus, with the dose of 400 kg ha-1 of P2O5 providing the highest height and the dose of 300 kg ha-1 of P2O5 providing the greatest stem diameter and the number of leaves. Up to 120 days old, gabiroba seedlings do not respond significantly to nitrogen fertilization.

PRODUCTION OF ORNAMENTAL PYRAMID PEPPER WITH REFLECTIVE MATERIAL ON BENCHES IN DIFFERENT ENVIRONMENTS

Pepper trees have great ornamental value due to the varied colors of their fruits. Thus, the objective was to evaluate the Pyramid cultivar's production in different cultivation environments using benches with reflective material. The experiment was carried out in two protected environments: a) agricultural greenhouse with 42-50% shade screen under the plastic film and b) agricultural screen with black monofilament screen with 18% shade. Inside the environments, the production system was tested with and without reflective material on the cultivation bench. The experiments were conducted in a completely randomized design, with four replicates and six plants per plot. Joint analysis was used to compare environments. At 45, 60, and 75 days after transplantation, plant height, stem diameter, number of leaves, canopy area, and number of fruits were evaluated. The agricultural greenhouse with a 42/50% shade screen under the plastic film provided the formation of higher plants with greater stem diameter, greater number of leaves and fruits, and greater top diameter than the screen with 18% shading. The reflective mirror material showed positive results only for plant height.

GERMINABILIDAD Y DESARROLLO INICIAL DE NUEVOS HÍBRIDOS INTRAESPECÍFICOS DE Theobroma cacao L; MALVACEAE

El objetivo de esta investigación fue evaluar la germinabilidad de semillas y el desarrollo inicial de híbridos interclonales de Theobroma cacao L. El ensayo se estableció en el campus experimental “La Teodomira”, Manabí, Ecuador. Se realizaron cruzamientos intraespecíficos entre cinco genotipos de T. cacao, los frutos obtenidos se cosecharon aproximadamente a los 180 días. Las variables estudiadas fueron: porcentaje de germinación y de emergencia, altura de planta, diámetro de tallo, número de hojas y contenido de clorofila en el área foliar. Se obtuvo un 97.8% de germinación a los ocho días luego de desmulización e imbibición y un 86.5% de emergencia, registrándose un mayor porcentaje de germinación y emergencia en la progenie derivada del cruce L11-H19 x EET-103. A los 120 días, el mayor diámetro de tallo se registró en la familia EET-558 x CCN-5 y la mayor altura en la familia EET-103 x L11-H19. En promedio se obtuvo 15 hojas por planta y 43.5 de clorofila SPAD a los 120 días. El contenido de clorofila en las hojas está condicionado por la edad fisiológica de las plántulas. No obstante, para futuras investigaciones se recomienda realizar evaluación en campo de estas progenies, en especial de aspectos fisiológicos involucrados con la producción de hojas y contenido de clorofila, pues estos podrían ser indicadores para selección de genotipos promisorios

Desenvolvimento da cultura do milho e carbono orgânico total sob diferentes fontes de adubos

Este trabalho objetivou avaliar o desenvolvimento inicial da cultura do milho adubado com diferentes fontes de adubos, e quantificar os teores de carbono orgânico total (COT) do solo. O experimento foi conduzido em vasos, com sete tratamentos e cinco repetições. Os tratamentos foram: adubo mineral (AM), adubo organomineral (AO), esterco bovino (EB), cama de frango (CF), lodo de esgoto (LE), compost barn (CB) e sem adubação (SA). As avaliações foram: altura de planta, diâmetro basal do caule e número de folhas aos 15, 30, 45 e 60 dias após semeadura (DAS), além de comprimento de raiz, volume de raiz, massa seca de parte aérea e raiz, e cálculo de massa seca (MS) por hectare aos 60 DAS, sendo também quantificado o COT do solo após a condução do experimento. O tratamento com AM apresentou maiores valores para altura de planta e diâmetro do caule até os 30 DAS, porém aos 60 DAS as plantas que receberam AO e EB apresentaram maior altura e maior diâmetro de caule, respectivamente. Os tratamentos AM, EB e CF obtiveram produção de MS acima de 3000 kg ha-1, já o LE e SA proporcionaram menor desenvolvimento das plantas. O solo que recebeu CF apresentou maior teor COT, de 13,00 g kg-1, e o solo SA e que recebeu aplicação de AM os menores teores de COT. A CF e EB demonstraram resultados semelhantes à AM para a maioria dos atributos morfobiométricos avaliados, contribuindo também para o aumento do COT do solo.

Supplemental Radiation Quality Influences Cucumber, Tomato, and Pepper Transplant Growth and Development

Supplemental lighting is required for the production of high-quality vegetable transplants in greenhouses when the photosynthetic daily light integral (DLI) is low. Light-emitting diodes (LEDs) are a promising alternative to high-pressure sodium (HPS) lamps. However, there are a limited number of studies that have evaluated how LED supplemental lighting spectral quality beyond blue (B) and red (R) radiation influences plant growth and development. Seeds of hybrid greenhouse seedless cucumber ‘Elsie’ (Cucumis sativus), tomato ‘Climstar’ (Solanum lycopersicum), and pepper ‘Kathia’ (Capsicum annuum) were sown and placed into a dark growth chamber until radicle emergence. Seedlings were grown in a greenhouse at a 25 °C constant temperature set point and under five lighting treatments. The supplemental lighting treatments delivered a total photon flux density (TPFD) of 120 μmol·m−2·s−1 for 16 h·d−1 based on an instantaneous threshold from HPS lamps or LEDs [three treatments composed of B (400–500 nm), R (600–700 nm), white, and/or far-red (FR; 700–800 nm) LEDs], and a control that delivered 25 μmol·m−2·s−1 from HPS lamps (HPS25). The LED treatments defined by their wavebands (TPFD in μmol·m−2·s–1) of B, green (G, 500–600 nm), R, and FR radiation were B20G10R75FR15, B25R95, and B30G30R60; whereas the HPS treatments emitted B7G57R47FR9 (HPS120) and B1G13R9FR2 (HPS25). Generally, cucumber, pepper, and tomato transplants under B30G30R60 and HPS120 supplemental lighting had the greatest stem diameter. Fresh weight and leaf area of all three species was greater when G radiation replaced R or B radiation. For example, leaf area and fresh weight of cucumber, tomato, and pepper increased (by 33%, 22%, and 49%; and 35%, 14%, and 56%, respectively) for plants under B30G30R60 supplemental lighting compared with plants under B25R95 supplemental lighting. The most compact cucumber and pepper transplants were those grown under B25R95 supplemental lighting, and the most compact tomatoes were those grown under the HPS25 (control) and B25R95 supplemental lighting. Tomato transplants under treatments providing ≥30 μmol·m−2·s−1 of G radiation had an increased incidence of leaf necrosis. From this study, we conclude that plant responses to supplemental lighting quality are generally genera-specific, and therefore high-wire transplants should be separated by genera to optimize production and quality. However, additional studies are required to provide complete LED supplemental lighting recommendations.

Dosage and timing of nitrogen fertilizer application on snap beans

Snap beans (Phaseolus vulgaris L.) belong to the same species as common beans and require similar management practices. Studies aimed at nitrogen fertilization in pod beans are scarce, but necessary, considering the demand from farmers for greater productivity of these beans. The objective of this study was to evaluate the effects of nitrogen fertilization in various doses and times of application on the snap beans production. The experimental design was completely randomized in a factorial scheme (2×7) + 1, represented by two doses of nitrogen (30 and 60 kg ha-1) and seven fertilization strategies (100% of the dose provided at sowing or phenological stages V3, V4, or R6; split, with 50% at sowing and 50% at V3, 50% at sowing and 50% at V4, or 50% at sowing and 50% at R6), plus a control (no added N). We analyzed stem length, stem basal diameter, number of trefoils, number and mass of commercially viable pods, and number and mass of total pods. Nitrogen fertilization with 30 kg ha-1 N divided 50% at sowing and 50% at V4 or 50% at sowing and 50% at R6 yielded larger and more numerous pods from plants with greater stem diameters.

Optimal LED Wavelength Composition for the Production of High-Quality Watermelon and Interspecific Squash Seedlings Used for Grafting

Watermelon is cultivated worldwide and is mainly grafted onto interspecific squash rootstocks. Light-emitting diodes (LEDs) can be implemented as light sources during indoor production of both species and their spectral quality is of great importance. The objective of the present study was to determine the optimal emission of LEDs with wide wavelength for the production of watermelon and interspecific squash seedlings in a growth chamber. Conditions were set at 22/20 °C temperature (day/night), 16 h photoperiod, and 85 ± 5 μmol m−2 s−1 photosynthetic photon flux density. Illumination was provided by fluorescent (FL, T0) lamps or four LEDs (T1, T2, T3, and T4) emitting varying wide spectra. Watermelon seedlings had greater shoot length, stem diameter, cotyledon area, shoot dry weight-to-length (DW/L) ratio, and Dickson’s quality index (DQI) under T1 and T3, while leaf area and shoot dry weight (DW) had higher values under T1. Interspecific squash seedlings had greater stem diameter, and shoot and root DW under T1 and T3, while leaf and cotyledon areas were favored under T1. In both species, T0 showed inferior development. It could be concluded that a light source with high red emission, relatively low blue emission, and a red:far-red ratio of about 3 units seems ideal for the production of high-quality watermelon (scion) and interspecific squash (rootstock) seedlings.

Growth characteristics, biomass yield and mineral concentrations in seven varieties of Napier grass (<i>Cenchrus purpureus</i>) at establishment in Kelantan, Malaysia

Growth characteristics, biomass yield and mineral concentrations were evaluated in a completely randomized design study of 7 Napier grass varieties. Data on tiller number per plant, plant height, leaf length, leaf width, stem diameter, leaf:stem ratio and dry matter (DM) yield, as well as concentrations of nitrogen, calcium, magnesium, phosphorus, sodium, potassium, zinc, copper, manganese and iron, were obtained at 2 months growth. The growth characteristics, DM yields and mineral concentrations (except phosphorus) varied significantly (P<0.01) among varieties. The variety Indian was tallest (221 cm) and produced the highest DM yield (6.3 t/ha), whereas Dwarf had the highest tiller number and leaf:stem ratio. Purple had the longest and Taiwan and Indian the widest leaves. Kobe, Pakchong and Purple had the greatest stem diameter. Concentrations of Ca, K and Na were greatest in Zanzibar, while Dwarf had the highest concentrations of N, Zn, Mn and Fe. Studies beyond the establishment phase over a range of seasons and in a range of environments at different ages of harvest are needed to confirm the merits of different Napier grass varieties in the study zone.

Comportamiento agronómico y fisiológico de maíces nativos del sureste de México


 México es el centro de origen y domesticación del maíz (Zea mays L.), en algunas regiones aún existen poblaciones criollas con potencial para generar variedades mejoradas. El objetivo de este estudio fue evaluar el comportamiento agronómico y fisiológico de doce poblaciones de maíz nativas del sureste de México. El experimento se realizó en Tizimín, Yucatán en el año 2017. Se evaluaron 32 parámetros correspondientes a variables vegetativas, fenológicas, agronómicas y fisiológicas. Los resultados mostraron una diferencia de 75 cm entre las plantas más bajas (Xn-69) y las de porte más alto (CNB), las plantas de la población DZ-252 presentaron mayor follaje (19.1 hojas) y mayor diámetro de tallo (26 mm), las poblaciones más precoces fueron CM y CCB (65.5 y 65.8 días, respectivamente). El 58% de las poblaciones evaluadas superó el rendimiento promedio de la región (4.5 t ha-1). El mayor rendimiento lo obtuvieron las poblaciones CM, Cro, H1 y SP2015 (117.7, 105.8, 111.5 y 109.5 g planta-1, respectivamente). Las poblaciones CM, DZ2015, Cja y Cro tuvieron mayor tasa fotosintética; sin embargo, la mayor eficiencia del uso del agua lo presentaron las poblaciones DZ-252 y XnQroo (8.9 μmol CO2/mmol H2O). La población CM destacó por su rendimiento y precocidad, la DZ-252 podría utilizarse como forraje por la cantidad de biomasa que generó y la XnQroo debería ser estudiada bajo condiciones de restricción hídrica por su eficiencia del uso del agua, estas tres poblaciones deberían incluirse en programas de mejoramiento genético.

Assessing Quantitative Criteria for Characterization of Quality Categories for Grafted Watermelon Seedlings

Vegetable grafting is a practice employed worldwide since it helps prevent biotic and abiotic disorders, and watermelon is one of the most important species grafted. The objective of this study was to set critical limits for the characterization of quality categories for grafted watermelon seedlings. Specifically, watermelon (scion) seedlings were grafted onto squash (rootstock) seedlings, moved into a healing chamber for 7 days, and then transferred into a greenhouse for seven more days. At 7 and 14 days after grafting, experienced personnel assessed grafted seedling quality by categorizing them. The categories derived were Optimum and Acceptable for both time intervals, plus Not acceptable at 14 days after grafting. Optimum seedlings showed greater leaf area, and shoot and root fresh and dry weights at both time intervals. Moreover, they had greater stem diameter, root-to-shoot ratio, shoot dry weight-to-length ratio and Dickson’s quality index compared to the other category at 14 days after grafting. Therefore, Optimum seedlings would likely develop into marketable plants of high quality, with better establishment in the field. Not acceptable seedlings showed considerably inferior development, while Acceptable seedlings were between the other categories, but were still marketable.

Silver nanoparticles preplant bulb soaking affects tulip production

ABSTRACTNanomaterials and particularly silver nanoparticles (AgNPs) have increased great interest in many fields of science. The element may affect plant growth and development but so far research studies have been scarce and their results disparate. Tulip is one of the most important ornamental plants and its production technology is constantly being improved. The aim of this study was to investigate the effects of AgNPs on growth and yield attributes of tulip cv. ‘Pink Impression’. Before planting, the tulip ‘Pink Impression’ bulbs were soaked in the following concentrations of AgNPs: 25, 50, 100 and 150 mg L-1. Control bulbs were soaked in deionized water. The plants were forced in a greenhouse for two growing seasons. The tulips treated with 100 mg L−1 AgNPs flowered earlier, had longer cut-flower stem, larger petals, greater stem diameter and cut-flower fresh weight. Moreover, at this concentration of AgNPs, they showed increased leaf greenness index (SPAD), stomatal conductance, root fresh weight, root length and produced daughter bulbs of the greatest weight. The study outcomes indicate that AgNPs may be used as plant growth promoters in horticulture.