Early Growth Variables Research Articles

Zinc oxide nanoparticle morphology modify germination and early growth of bell pepper seedlings

In recent years, interest in nutrient and nanoscale biostimulant use in agriculture to improve seed germination and crop productivity has increased. Nanoparticle seed priming has improved growth and quality in crops of agricultural value. The following study shows the effect of seed priming on bell pepper RZ F1 (35-71) with zinc oxide nanoparticles (ZnO NPs) with different morphology: spherical and hexagonal. Bell pepper seeds were primed with ZnO NPs at different doses, 50 and 100 mg L-1. The study was carried out in two phases. The first phase consisted of an in-vitro study in a germination chamber (28°C), where early growth variables were assessed: germination percentage, radicle, plumule and hypocotyl length; while the second phase was carried out under greenhouse conditions, where variables such as plant height, stem diameter, dry weight, leaf area, total chlorophyll and phenols were assessed, 45 days after sowing. Seed priming with different morphology ZnO NPs showed a positive influence, 100 mg L-1 dose giving the best results for early growth parameters, as well as for plant height, stem diameter, leaf area, total chlorophyll and phenolic content. These results suggest that ZnO NPs can be considered a promising seed preparation agent to improve germination, early growth parameters, and chlorophyll and phenolic contents.

Potential suppressive effects of Mexican poppy weed residues on germination and early growth of maize and pearl millet crops

Argemone ochroleuca allelochemical properties have been reported but not empirically tested on economically important staple cereal crops. Therefore, the objective of this study was to determine the potential Allelopathic effects of the alien weed’s residues on germination and early-growth of maize (Zea mays L.) and Pearl millet (Pennisertum glaucum). Allelopathic effects of A. ochroleuca on maize and millet seed germination were tested in a 2 (shoot and root) x 11 (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100g/L water) factorial treatment arrangement in CRD in an incubator placed in a laboratory. Whereas effects of the weed extracts on the same crops’ early-growth were tested in a 2 (shoot and roots) x 8 (0, 2, 4, 6, 8, 10, 12 and 14g ground-powdered extracts) factorial arrangement in RCBD under laboratory conditions. Maize and millet germination percentage, germination speed, mean germination time, mean daily germination, plumule and radicle length were measured for germination test, whereas, plant height, stem diameter, root and shoot mass were used as indicators of A. ochroleuca suppression of early plant growth. Relative to untreated control, concentration equal to and greater than 10g/L aqueous extracts of A. ochroleuca reduced millet and maize seed germination variables by 10–100% and 28–56%, respectively, while early-growth variables were reduced by 66–100% and 4–37%, respectively. Argemone ochroleuca shoot extracts were more suppressive than root extracts on germination and early growth of the two crops. In conclusion, A. ochroleuca Allelopathic effects were concentration and plant-part dependent, inhibitory effects increased with concentrations, with extracts from shoots being more Allelopathic on measured variables when compared to root extracts. As A. ochroleuca continues to spread yearly without any control strategies in place, a threat exist on maize and Pearl millet production especially in communal farming areas where improved management strategies are non- existent. Key words: Allelopathic, Argemone ochroleuca, germination, growth, millet, maize, plumule, radicle

Growing Up Down South: Spatial and Temporal Variability in Early Growth of Fuegian Sprat Sprattus fuegensis From the Southwest Atlantic Ocean

The Fuegian sprat Sprattus fuegensis represents one of the most important pelagic resources in the Southwest Atlantic Ocean (SWAO), exerting a crucial ecological role as an intermediary link in Patagonian food webs. Otolith microstructure of 217 age-0 sprats were analyzed aiming to characterize growth patterns and possible environmental effects over them. Samples were gathered during three oceanographic surveys (spring 2014; autumns 2016, 2017) in Tierra del Fuego (TDF) and the Marine Protected Area Namuncura-Burdwood Bank (MPAN-BB), the first Argentinian open-sea marine protected area. Daily growths (DG) of larvae and post-larvae were estimated by individually modeling size and otolith radius relationships through back-calculation procedures using potential and linear functions respectively. Increment widths (IW) and DG values and trajectories were assessed for older sprats (i.e. survivors) sampled in the autumn surveys considering the habitat, year sampled and sprats’ hatching seasons, and were additionally evaluated in relation to sea-surface temperature (SST). IW and DG trajectories differed primarily according to the habitat sampled and sprats’ hatching seasons. Overall, strong coupling was detected between IW and DG trajectories with SST in both habitats. However, statistical assessment on particular comparisons showed that this general trend is not strictly invariant. Even though several results pinpointed a positive correlation between IW and DG with SST, the highest DG were estimated for summer- and autumn-born sprats sampled in 2016 in the MPAN-BB, period and habitat with the lowest SST values. These results unveil a complex relationship between spatial and temporal variability during early growth of Fuegian sprats, supplying relevant information that could be used in the creation of adequate ecosystem based management strategies in the SWAO.

Bayesian network modeling of early growth stages explains yam interplant yield variability and allows for agronomic improvements in West Africa

Yams (Dioscorea spp.) are important species, especially for resource-poor farmers of West Africa, where crop yields are affected by early plant size hierarchy linked with uneven emergence. Although the causes of this phenomenon are not fully known, yams, like other vegetatively propagated crops, have heavy planting material that is liable to induce such interplant variability. In addition, planting practices may mitigate this phenomenon via the selection of the seed-tuber size or state. To gain further insight into yam interplant variability, this study identified and quantified, for the first time, the direct and indirect dependency between planting practices, early growth variables and yield components of Dioscorea rotundata and Dioscorea alata, the two main food yam species. The experimental dataset came from six field trials carried out in Benin at two locations between 2007 and 2009. Additive Bayesian network modeling was used for structure discovery—its directed acyclic graph offers an ideal background for discussing complex systems when theoretical knowledge is lacking, e.g., for yams. Here we found that the emergence date was the only direct cause of plant yield variability common to both species. For D. rotundata, we observed a direct contribution of the cataphyll number to the plant tuber weight. These combined results suggest the existence of some uncontrolled latent variables (i.e., seed-tuber physiological age and reserves). For D. alata, the model did not reveal any effect of seed-tuber size, despite a strong effect noted for D. rotundata. We suggest that the transposition of traditional native D. rotundata planting practices may have led to oversized D. alata seed-tubers, resulting in wastage of planting material. This study demonstrated that traditional West African cropping systems have a serious drawback concerning the uncontrolled wide range of physiological ages and reserves in seed-tuber lots, which affect the plant size hierarchy and ultimately the marketable yield. (Resume d'auteur)

Infant Growth after Preterm Birth and Mental Health in Young Adulthood.

ObjectivesFaster growth after preterm birth benefits long-term cognitive functioning. Whether these benefits extend to mental health remains largely unknown. We examined if faster growth in infancy is associated with better self-reported mental health in young adults born preterm at very low birth weight (VLBW) (<1500g).Study DesignAs young adults, participants of the Helsinki Study of Very Low Birth Weight Adults self-reported symptoms of depression and attention deficit/hyperactivity disorder (ADHD) (n = 157) and other psychiatric problems (n = 104). As main predictors of mental health outcomes in linear regression models, we used infant weight, length, and head circumference at birth, term, and 12 months of corrected age, and growth between these time points. Growth data were collected from records and measures at term and at 12 months of corrected age were interpolated. Additionally, we examined the moderating effects of intrauterine growth restriction.ResultsSize at birth, term, or 12 months of corrected age, or growth between these time points were not associated with mental health outcomes (p-values >0.05). Intrauterine growth restriction did not systematically moderate any associations.ConclusionsDespite the high variability in early growth of VLBW infants, the previously described association between slow growth in infancy and poorer cognitive functioning in later life is not reflected in symptoms of depression, ADHD, and other psychiatric problems. This suggests that the development of cognitive and psychiatric problems may have dissimilar critical periods in VLBW infants.

Infant Growth after Preterm Birth and Neurocognitive Abilities in Young Adulthood

To examine whether faster growth from birth to term (40 postmenstrual weeks) and during the first year thereafter was associated with better neurocognitive abilities in adults born preterm with very low birth weight (VLBW; <1500 g). Weight, length, and head circumference data of 103 VLBW participants of the Helsinki Study of Very Low Birth Weight Adults were collected from records. Measures at term and at 12 months of corrected age were interpolated. The participants underwent tests of general neurocognitive ability, executive functioning, attention, and visual memory at mean age of 25.0 years. Faster growth from birth to term was associated with better general neurocognitive abilities, executive functioning, and visual memory in young adulthood. Effect sizes in SD units ranged from 0.23-0.43 per each SD faster growth in weight, length, or head circumference (95% CI 0.003-0.64; P values <.05). After controlling for neonatal complications, faster growth in head circumference remained more clearly associated with neurocognitive abilities than weight or length did. Growth during the first year after term was not consistently associated with neurocognitive abilities. Within a VLBW group with high variability in early growth, faster growth from birth to term is associated with better neurocognitive abilities in young adulthood. Neurocognitive outcomes were predicted, in particular, by early postnatal head growth.

Associations of Birth Order With Early Growth and Adolescent Height, Body Composition, and Blood Pressure: Prospective Birth Cohort From Brazil

Birth weight has been inversely associated with later blood pressure. Firstborns tend to have lower birth weight than their later-born peers, but the long-term consequences remain unclear. The study objective was to investigate differences between firstborn and later-born individuals in early growth patterns, body composition, and blood pressure in Brazilian adolescents. The authors studied 453 adolescents aged 13.3 years from the prospective 1993 Pelotas Birth Cohort. Anthropometry, blood pressure, physical activity by accelerometry, and body composition by deuterium were measured. Firstborns (n = 143) had significantly lower birth weight than later borns (n = 310). At 4 years, firstborns had significantly greater weight and height, indicating a substantial overshoot in catch-up growth. In adolescence, firstborns had significantly greater height and blood pressure and a lower activity level. The difference in systolic blood pressure could be attributed to variability in early growth and that in diastolic blood pressure to reduced physical activity. The magnitude of increased blood pressure is clinically significant; hence, birth order is an important developmental predictor of cardiovascular risk in this population. Firstborns may be more sensitive to environmental factors that promote catch-up growth, and this information could potentially be used in nutritional management to prevent catch-up “overshoot.”

Coherent growth and diet patterns in juvenile spot ( Leiostomus xanthurus Lacepéde) reflect effects of hydrology on access to shoreline habitat

A previous study of hydrological effects on early recruitment of estuary-dependent spot ( Leiostomus xanthurus Lacepéde) underscored the importance of fluctuations in temperature and salinity on early growth; however, considerable variability in early growth remained unexplained. Hydrology might also influence early growth by mediating access to emergent shoreline vegetation (ESV). In this study, access to ESV was mediated by hydrology over the 38-day study period. Furthermore, otolith microstructure inferred that standard deviation (S.D.) and mean growth decreased with access to ESV. Diets of fish during onshore and offshore frontal passages were consistent with the growth patterns. Less access to ESV corresponded with more variable and greater amounts of food; whereas more access to ESV coincided with the opposite diet pattern. Ontogenetic diet relationships were well defined during ESV access, whereas they were undefined during ESV restriction. This study illustrates how physical forcing can indirectly affect early growth through complex interactions between abiotic and biotic variables.

Environmental influences on larval duration, growth and magnitude of settlement of a coral reef fish

The influence of environmental variables on the planktonic growth, pelagic larval duration and settlement magnitude was examined for the coral reef surgeonfish Acanthurus chirurgus. Newly settled fish were collected daily from patch reefs in the San Blas Archipelago, Caribbean Panama for 3.5 years. Environmental influences on growth were examined at three different life history stages: from 0 to 6 days, 7 to 25 days and from 26 to 50 days after hatching. Larval growth was correlated, using multiple regression techniques, with a combination of factors including solar radiation, rainfall, and along-shore winds. Depending on the life history stage, these accounted for 13–38% of the variation in growth rates when all the months were included in the analyses. Correlations between environmental variables and growth also varied among seasons and were stronger in the dry than in the wet season. During the dry season solar radiation, rainfall and along-shore winds described 57%, 86% and 74% of the variability in growth between 0 and 6 days, 7 and 25 days and 26 and 50 days, respectively. During the wet season rainfall, along-shore winds and temperature only described 38% of the variability in early growth and 27% of growth just before settlement. No significant model was found to describe growth 7–25 days after hatching during the wet season. Rainfall, solar radiation and along-shore winds were negatively correlated with growth up to 25 days after hatching but positively correlated as larvae approached settlement at a mean age of 52 days. Over 65% of the variability in pelagic larval duration was accounted for by a regression model that included solar radiation and along-shore winds. When data sets from wet and dry seasons were analysed separately, along-shore winds accounted for 67% of the change in larval duration in the dry season, and solar radiation accounted for 23% of the variation in larval duration in the wet season. Only 22% of the variability in settlement intensity could be described by solar radiation and temperature, when all months of the year were included in the analysis. Solar radiation and rainfall were included in a regression model that accounted for 40% of the variation in numbers of fish settling during the dry season. This study suggests that the levels of solar radiation, along-shore winds and rainfall during the early larval life can have important effects on the growth, larval duration and consequently, the settlement magnitude of marine fishes. Results also highlight the need to account for seasonality and ontogeny in studies of environmental influences.

Factors influencing production of inflorescence-derived somatic seedlings of sweetgum

Somatic embryos derived from staminate inflorescence tissues of three mature sweetgum (Liquidambar styraciflua) trees were tested for germination and conversion frequencies and early growth variables following pregermination cold treatments. Individual mature embryos were selected from repetitively embryogenic cultures maintained on Woody Plant Medium (WPM) with 1 mg l−1 naphthaleneacetic acid and cultured on basal WPM at 10 8C for 0, 4 or 8 weeks prior to being transferred to WPM germination medium in the light. After 4 weeks, germinated embryos were planted in potting mix in an acclimatization chamber, grown for an additional 8 weeks and evaluated for conversion and growth. Conversion frequency, which ranged up to 80%, was affected by ortet and clonal line, while the number of first-order lateral roots was affected by ortet, clonal line and cold treatment, with 8 weeks of cold promoting the highest number.

Growth of wheat after damage by, and effects of ethylene dibromide on, a field population of Heterodera avenae

Growth of two wheat cultivars (Cook and Egret) after damage by H. avenae, and the effects of EDB on growth and on the nematode were assessed in a field trial. Most early growth variables of both cultivars were delayed by the nematode and EDB largely removed the effects of the nematode. EDB reduced the population of hatched nematodes and delayed hatching of encysted eggs for about 6 weeks, after which hatching resumed. It did not reduce per cent hatch or infectivity. Cook, a later-maturing cultivar than Egret, had more damage on nodal roots when nematode hatching was delayed following treatment with EDB. Both cultivars were equally susceptible to the nematode, but EDB reduced the multiplication of the nematode.