Early Vegetative Growth Research Articles

Growth of paddy inoculated by Azotobacter spp. in tetracycline contaminated culture

Excess tetracycline consumed by the cattle is excreted in the form of urine or feces commonly used as organic matter for rice production. The plant growth promoting Azotobacter that used as biofertilizer is usually carried by manure as the source of organic matter. Tetracycline residues in the manure might interfere the plant growth. The objective of this preliminary study was to verify the influence of two Azotobacter isolates on early vegetative growth of rice grown in media contaminated tetracycline. Bioassay was performed by using filter paper moistened with liquid growth media media with some level of tetracycline. Paddy seed was grown for 12 days on the paper and inoculated with Azotobacter c2a9 from Maluku soil and Azotobacter K4 from West Java soil. In general, 25-75 mg/L of tetracycline significantly decreased shoot height and root length of paddy seedlings inoculated with Azotobacter c2a9. Lower level tetracycline, 15 mg/L, increased shoot heights and root lengths of paddy seedling grown with Azotobacter K4, a saline resistant isolate. However 30 mg/L of tetracycline reduce all parameters.

Drought indices based on MODIS data compared over a maize-growing season in Songliao Plain, China

Many indices based on MODIS data are used to monitor the process of agricultural drought, such as apparent thermal inertia (ATI) and temperature vegetation dryness index (TVDI). Notable differences in performance and geographic predictions exist among these indices. We statistically evaluated the performance of different drought indices for a known drought process in 2014 in the typical rainfed maize region of Songliao Plain, China, using a linear regression model based on the relationships between indices and soil moisture data. Our results show that during the growth season of May to September, the indices performed independently with changing curves, particularly in different phenological periods. By contrast, correlations tended to be higher for ATI than for other indices in the early vegetative growth stage, whereas small differences were detected among the other indices in the late vegetative to late reproductive growth stages. Our results confirm that the TVDI can be the best choice to detect agricultural drought in the study area.

Modulation of photosynthate supply by CO2 elevation affects the post‐head‐emergence frost‐induced grain yield loss in wheat

AbstractPost‐head‐emergence frost (PHEF) has a detrimental impact on grain yield of wheat, and an enhanced photosynthate supply could alleviate the negative impact. However, modulation of photosynthate availability at different growth stages may exert different effects on the plant physiology and grain yield. The objective of this study was to investigate the roles of the enhanced photosynthate supply by growing the plants at elevated [CO2] (800 ppm) during different growth stages on yield performance of wheat exposed to PHEF. The results showed that the PHEF caused a high grain yield loss in wheat, and an increase in photosynthate supply during the reproductive growth stage mitigated the negative impact, whereas that at vegetative growth stage exacerbated the negative impact of PHEF. The opposite effects exerted by the enhanced photosynthate supply at vegetative stage versus at reproductive stage on yield performance could be associated with its distinguished roles in influencing plant physiology at the two growth stages. The positive effect of the increased photosynthate supply at reproductive stage was due to an improved grain filling and regeneration of effective tillers upon recovery from frost, whereas the negative effects of the enhanced photosynthate supply at vegetative growth stage were primarily due to an accelerated early vegetative growth that increased the sensibility of the plants to PHEF.

Chlorophyll a fluorescence analysis can detect phosphorus deficiency under field conditions and is an effective tool to prevent grain yield reductions in spring barley (Hordeum vulgare L.)

Phosphorus (P) is an essential macronutrient with major impacts on global crop productivity. Recent work showed that chlorophyll a fluorescence analysis can be used as a sensitive indicator of latent P deficiency across different plant species. Here, we demonstrate that chlorophyll a fluorescence OJIP transients are a powerful tool for early detection of P deficiency directly in the field. Barley was grown in a P responsive field. One treatment received 30 kg P ha−1 at sowing, four treatments were fertilized with P at 26, 35, 46 or 56 days after sowing (DAS), respectively, and the final treatment did not receive any P throughout the experiment. Chlorophyll a fluorescence measurements, multi-elemental leaf analysis, and growth stage evaluation were performed 26, 35, 46, 56, and 69 DAS. Phosphorus deficiency during early vegetative growth irreversibly affected plant development including tiller outgrowth and grain yields. However, in the present study, yield reduction could be avoided if short-term P deficiency was corrected by application of P fertilizer no later than 35 days after sowing, when plants had not yet entered the tillering stage. The chlorophyll a fluorescence OJIP transients were able to detect latent P deficiency in this critical phase, thereby providing an opportunity for avoiding a potential yield reduction of up to 27 hkg ha−1. It was further noted, that chlorophyll a fluorescence analysis and P leaf tissue analysis should be performed during early vegetative growth, as probable remobilization of P within the plant during tillering and shoot differentiation masks the effects of P deficiency at the single leaf level. It is concluded that chlorophyll a fluorescence analysis provides a unique opportunity for a timely detection and correction of P deficiency under field conditions to prevent yield reductions.

Transcriptome profiling uncovers β-galactosidases of diverse domain classes influencing hypocotyl development in jute (Corchorus capsularis L.)

Enzyme β-galactosidase (EC 3.2.1.23) is known to influence vascular differentiation during early vegetative growth of plants, but its role in hypocotyl development is not yet fully understood. We generated the hypocotyl transcriptome data of a hypocotyl-defect jute (Corchorus capsularis L.) mutant (52,393 unigenes) and its wild-type (WT) cv. JRC-212 (44,720 unigenes) by paired-end RNA-seq and identified 11 isoforms of β-galactosidase, using a combination of sequence annotation, domain identification and structural-homology modeling. Phylogenetic analysis classified the jute β-galactosidases into six subfamilies of glycoside hydrolase-35 family, which are closely related to homologs from Malvaceous species. We also report here the expression of a β-galactosidase of glycoside hydrolase-2 family that was earlier considered to be absent in higher plants. Comparative analysis of domain structure allowed us to propose a domain-centric evolution of the five classes of plant β-galactosidases. Further, we observed 1.8–12.2-fold higher expression of nine β-galactosidase isoforms in the mutant hypocotyl, which was characterized by slower growth, undulated shape and deformed cell wall. In vitro and in vivo β-galactosidase activities were also higher in the mutant hypocotyl. Phenotypic analysis supported a significant (P ≤ 0.01) positive correlation between enzyme activity and undulated hypocotyl. Taken together, our study identifies the complete set of β-galactosidases expressed in the jute hypocotyl, and provides compelling evidence that they may be involved in cell wall degradation during hypocotyl development.

Artificial warming-mediated soil freezing and thawing processes can regulate soybean production in Northeast China

Northeast China with seasonally frozen soil is quite sensitive to global warming. The changes in soil freezing and thawing processes initiated by global warming could alter the hydrological cycle of agricultural fields. A paired-plot experiment was conducted in frozen agricultural soils in Northeast China to examine the impacts of simulated warming on soil freezing and thawing processes and on soybean production. Infrared radiators were used to simulate global warming, rising surface soil temperature (5 cm depth) by 2.86 °C. We showed that, artificial warming caused the freeze duration shortened by 22 days, and the thaw duration shortened by 17 days resulting in the mean duration of soil freezing-thawing significantly shortened by 39 days and the maximum frost depth reduced by about 40 cm. Simulated warming had no significant effect on the average annual freeze-thaw cycle frequency. Warming induced a larger water accumulation in the 0–100 cm soil layer during 2014–2015 soil freezing period. In the dry year of 2015, warming did not significantly affect surface soil moisture during period from sowing date to VC (soybean cotyledon) date. Thus, warming-induced an increase in soybean yield in the dry year may be attributable to the positive effect of enhanced soil temperature on soybean growth (aboveground dry matter accumulation) and consequent on soybean production. In the wet year of 2014, warming decreased surface soil moisture from sowing date to the date of VC stage because warming advanced the soil thaw-end date in 20–60 cm layer by 15 days. This decline in surface soil water availability may potentially offset the positive effects of increased soil temperature on soybean yield, thus warming effects on soybean production was neutral in the wet year. Our findings highlight the potential role of seasonally soil freezing and thawing dynamics in regulating soybean to global warming and suggested that warming effects on soil water dynamics during soil freezing and thawing periods, and subsequent on the surface soil water availability at the early vegetative stage and soybean production were associated with the hydrological year. We conclude that under current precipitation patterns, the no response of soil surface water availability to warming during early vegetative growth, coupled with warming-mediated increases in soil temperature, might improve soybean production during dry years in Northeast China.

Apical bud break and early vegetative shoot growth improving the mango malformation development: a new point of view

Mango malformation induced by Fusarium spp. is one of the most destructive diseases worldwide. The production losses vary from 50 to 80%. Mango growth is intermittent being characterized by resting periods (RP) intercalary between each vegetative flow. Each new flush promotes changes in the intensity of epidemics, but the interaction of the RPs on the pathogen virulence and pathogenesis are unknown. To provide some information about this interaction, the effect of Fusarium spp. infection on incubation periods (PI), maximum severity (Ymax) and days to maximum severity (DYmax) was compared in nursery plants of cvs ‘Mallika’ and ‘Haden’ inoculated in the resting and active early growth (juvenile) stages, using the veneer grafting technique to end the rest phase in 2016. When both cultivars were inoculated in the resting stage, at 14 and 0 incubation days before grafting (dbg), ‘Haden’ was more susceptible than ‘Mallika’ showing quicker PIs and greater DYmax and Ymax in 42, 55 and 82% respectively. Likewise, ‘Haden’ shoots inoculated during resting stages or active early growth, at 22 days after grafting (dag), had a shortest PI and DYmax values, by up to 32 and 45% respect to mature inoculated shoots that remained attached to the plant. Ymax was not affected by the phenology of the inoculated shoots and PI were higher only in shoots inoculated at 75–85 dag (P < 0.05%). Middle and apical cross sections of mature and juvenile ‘Haden’ and ‘Mallika’ shoots observed under scanning electron microscope showed contrasted anatomical differences in tissue differentiation.

Comparative study of early growth stages of 25 guar (Cyamopsis tetragonoloba L.) genotypes under elevated salinity

Thar region in Pakistan has an extremely arid climate and agriculture in the region is facing the dual challenges of freshwater scarcity and elevated salinity. Long-term viability of agriculture in this region depends on selection of appropriate crops/cultivars that can withstand the higher salinity. Guar can be a viable fodder, vegetable and industrial crop in water scarce areas but its salinity tolerance varies widely among genotypes. This pot culture study conducted outdoor, evaluated early vegetative growth of 25 guar genotypes under four salinity levels (0.6, 3, 6 and 9 dS m−1). Length, fresh weight, and dry weights of shoot and root samples and monovalent cation concentrations in leaf samples were determined to evaluate genotypes performance after 15, 30 and 45 days of sowing. Results indicated a wide genotypic variation in length, fresh and dry weights of shoot and roots at different salinity levels. Selective ion uptake was the dominant salinity tolerance mechanism, with tolerant cultivars having higher K and higher K/Na ratios at higher salinity levels. Out of 25 guar genotypes, eight genotypes performed well under the highest level of irrigation water salinity (9.0 dS m−1) evaluated in this study and were considered to be salt tolerant. All the genotypes registered 50% or more growth at 6 and 3 dS m−1 compared to that at control. Our study results indicated a potential for select cultivars of guar in the salt affected regions of the world. Growth variability in guar genotypes at different salinity levels warrant further examination of these results under field conditions.

The critical period for yield and quality determination in canola (Brassica napus L.)

Despite its global significance as an edible oil and biofuel, the critical period for yield determination in canola (edible oilseed rape – Brassica napus L.) has not been determined in the field. Field experiments were conducted at two contrasting sites in southern Australia where 100 °Cd shading periods (15% PAR transmitted) were applied from early vegetative growth until maturity to identify the developmental period when the crop was most sensitive to stress. Despite the significant difference between the two sites for yield in the unshaded control (450 g m−2 in New South Wales, and 340 g m−2 in South Australia), the critical period was consistent at both sites extending from 100 to 500 °Cd after the start of flowering (BBCH60), and centred 300 °Cd after BBCH60. Seed number (seed m−2) was reduced by an average of 48% in the critical period, generated in equal parts by reduced pod m−2 in the early part of the period, and reduced seed pod−1 in the latter part. Reduced seed number was partially compensated by an increase in seed size of 29%. These trends were similar on the branches and main stem. On the main stem, the timing of the critical period moved from earlier to later from lower to upper pods linked to the timing of their development. Seed oil content declined and protein content increased under shading in the critical period, while both oil and protein yield (kg m−2) were reduced by 40–50% and 30–40% respectively. The critical period is coincident with the greatest number of near-open buds and newly opened flowers, which are highly sensitive to assimilate supply for ovule development. Both pod abortion and restricted capacity for compensatory growth of surviving pods are consequences of assimilate restriction on developing ovules. Identification of the critical period provides a useful target for breeding and management strategies to maximize productivity.

The effect planting hole size and manure on vegetative growth of golden teak (Tectona grandis L.)

Cultivation of the golden teak ( Tectona grandis L.) requires the planting hole size and appropriate use of manure. The size of planting hole provides plant growth, so that the plant can grow with optimum and appropriate use of manure to provide nutrients for the plants. . The aims of the study was to obtain an interaction between planting hole size and manure on vegetative growth phase of golden teak. Treatments tested in this study were with 4 treatment of planting hole size as the first factor and 3 levels of manure as the second factor. The twelve treatments were arranged in a factorial randomized block desiagn with three replicates. Variable measured plant height, number of leaves, and the flush changes to mature. The results showed that there were no interactions between the planting hole size and goat manure on early vegetative growth of golden teak plants. The planting hole size treatment showed significant effects on some variables height of plant, number of leaves and flush change to mature leaves. Manure treatment showed no significant effect for all variables. The observation variables that showed no significant differences height of plant, number of leaves and flush change to mature leaves.

Impact of Halo and Hormonal Priming on Early Vegetative Growth Phase of Rice Var. MTU 7029

Impact of Halo and Hormonal Priming on Early Vegetative Growth Phase of Rice Var. MTU 7029

Impact of Erratic Rainfall from Climate Change on Pulse Production Efficiency in Lower Myanmar

Erratic rainfall has a detrimental impact on crop productivity but rainfall during the specific growth stage is rarely used in efficiency analysis. This study focuses on this untapped point and examines the influence of rainfall specifically encountered during the sowing stage and early vegetative growth stage and the flowering stage of pulses on productivity and efficiency in Lower Myanmar using data from 182 sample farmers. The results of a stochastic frontier production function reveal that rainfall incidence during the flowering season of pulses has a negatively significant effect on yield while replanting crops after serious damage by rain increases productivity. Controlled rainfall variables, seed rate, human labor and land preparation cost are important parameters influencing pulses yield. In the efficiency model, levels of yield loss have a negative impact while being a male household head, access to government credit, access to training, locating farms in the Bago Region and possessing a large area of pulses have a positively significant effect on technical efficiency. Policy recommendations include the establishment of a safety network, such as crop insurance to protect farmers from losses due to unpredictable weather conditions, promoting training programs on cultural practices adapted to climate change, wide coverage of extension activities, giving priority to small-scale farmers and female farmer participation in training and extension activities and increasing the rate of credit availability to farmers.

Changes in essential oil accumulation of Moldavian balm (Dracocephalum moldavica L.) in response to phosphate biological and chemical fertilizer

ABSTRACTA field experiment was carried out with a split plot arrangement based on a randomized complete block design with three replications in 2014. Triple super phosphate (0, 3.75, 7.5, 11.25 and 15 g m−2) was applied in main plots and phosphate bio-fertilizer (seed inoculation and topdressing) was allocated to sub plots. Results indicated that application of plants with phosphorus (P) bio-fertilizer as topdressing increased plant height and the number of the lateral branches under low levels of chemical P fertilizer, while plants from seed inoculated with P bio-fertilizer had more of those traits under high levels of chemical P fertilizer. Maximum leaf and flower dry weights were found under the lowest level of chemical P fertilizer. Moldavian balm plant demonstrated highly responsiveness to biological fertilizers in terms of increase in essential oil (EO) percentage and yield. It can be concluded that the effects of bio-fertilizer as seed inoculation is more during the early vegetative growth of plants. Thus, plants from seeds inoculated with P bio-fertilizer treatment had more biomass and EO percentage under high levels of chemical P fertilizer.

The vegetative nitrogen response of sorghum lines containing different alleles for nitrate reductase and glutamate synthase

Improving the nitrogen (N) responsiveness of crops is crucial for food security and environmental sustainability, and breeding N use efficient (NUE) crops has to exploit genetic variation for this complex trait. We used reverse genetics to examine allelic variation in two N metabolism genes. In silico analysis of the genomes of 44 genetically diverse sorghum genotypes identified a nitrate reductase and a glutamate synthase gene that were under balancing selection in improved sorghum cultivars. We hypothesised that these genes are a potential source of differences in NUE, and selected parents and progeny of nested association mapping populations with different allelic combinations for these genes. Allelic variation was sourced from African (Macia) and Indian (ICSV754) genotypes that had been incorporated into the Australian elite parent R931945-2-2. Nine genotypes were grown for 30 days in a glasshouse and supplied with continuous limiting or replete N, or replete N for 27 days followed by 3 days of N starvation. Biomass, total N and nitrate contents were quantified together with gene expressions in leaves, stems and roots. Limiting N supply universally resulted in less shoot and root growth, increased root weight ratio and reduced tissue nitrate and total N concentrations. None of the tested genotypes exceeded growth or NUE of the elite parent R931945-2-2 indicating that the allelic combinations did not confer an advantage during early vegetative growth. Thus, the next steps for ascertaining potential effects on NUE include growing plants to maturity. We conclude that reverse genetics that take advantage of rapidly expanding genomic databases enable a systematic approach for developing N-efficient crops.

Chemical composition and antioxidant activity of essential oils in Origanum vulgare subsp. gracile at different phenological stages and plant parts

Origanum vulgare, a popular flavoring herb, is valued for several biological properties. The present study focused on the chemical composition and antioxidant activity of the essential oils of Origanum vulgare subsp. gracile in different plant parts and at different phenological stages. Qualitative and quantitative analyses of the essential oil identified 41 constituents that varied with plant age and organ. The phenolic monoterpenoid carvacrol (18.1–79.2%) was predominant in all the essential oil samples. Other major constituents were p-cymene (3.9–18.0%), γ-terpinene (0.9–15.8%), carvacrol methyl ether (0.8–9.9%), and (Z)-α-bisabolene (0.5–8.7%). Among the different plant parts and phenological growth stages, the highest levels of carvacrol were identified in the essential oils from flowers (79.2%), roots (70%), and the early vegetative growth (67.34%). All the essential oils exhibited high radical-scavenging properties as shown in the DPPH* assay. The essential oils from flowers, however, exhibited the highest antioxidant activity and could be used as a preservative agent on an industrial scale. Practical applications Results suggest that yield and quality of oregano essential oil can be scaled-up by optimizing plant development and harvesting time. Also, the essential oils from flowers exhibited the highest antioxidant activity and could be used on an industrial level to reduce oxidation in food products.

Unraveling Salt Tolerance Mechanisms in Halophytes: A Comparative Study on Four Mediterranean Limonium Species with Different Geographic Distribution Patterns.

We have performed an extensive study on the responses to salt stress in four related Limonium halophytes with different geographic distribution patterns, during seed germination and early vegetative growth. The aims of the work were twofold: to establish the basis for the different chorology of these species, and to identify relevant mechanisms of salt tolerance dependent on the control of ion transport and osmolyte accumulation. Seeds were germinated in vitro, in the presence of increasing NaCl concentrations, and subjected to “recovery of germination” tests; germination percentages and velocity were determined to establish the relative tolerance and competitiveness of the four Limonium taxa. Salt treatments were also applied to young plants, by 1-month irrigation with NaCl up to 800 mM; then, growth parameters, levels of monovalent and divalent ions (in roots and leaves), and leaf contents of photosynthetic pigments and common osmolytes were determined in control and stressed plants of the four species. Seed germination is the most salt-sensitive developmental phase in Limonium. The different germination behavior of the investigated species appears to be responsible for their geographical range size: L. narbonense and L. virgatum, widespread throughout the Mediterranean, are the most tolerant and the most competitive at higher soil salinities; the endemic L. santapolense and L. girardianum are the most sensitive and more competitive only at lower salinities. During early vegetative growth, all taxa showed a strong tolerance to salt stress, although slightly higher in L. virgatum and L. santapolense. Salt tolerance is based on the efficient transport of Na+ and Cl− to the leaves and on the accumulation of fructose and proline for osmotic adjustment. Despite some species-specific quantitative differences, the accumulation patterns of the different ions were similar in all species, not explaining differences in tolerance, except for the apparent activation of K+ transport to the leaves at high external salinity, observed only in the most tolerant L. narbonense and L. virgatum. This specific response may be therefore relevant for salt tolerance in Limonium. The ecological implications of these results, which can contribute to a more efficient management of salt marshes conservation/regeneration programs, are also discussed.

Predicting phosphorus availability to spring barley (Hordeum vulgare) in agricultural soils of Scandinavia

In order to utilize the limited phosphorus (P) resources most efficiently, it is crucial to limit over- and under-fertilization in plant production. In this study we evaluated the Diffusive Gradients in Thin films (DGT) technique as a method to determine plant P availability in agricultural soils. DGT measurements were compared to a range of well-established and frequently used soil extraction methods. In order to select P responsive soils for field trials in multiple locations, a spring barley (Hordeum vulgare) pot experiment, with 34 soils from different locations in Denmark, Sweden, Norway and Finland was designed and plants were grown with or without P fertilization. The soils were analyzed for P availability with DGT and three soil extraction methods using the following extractants: sodium-bicarbonate (Olsen-P), ammonium lactate (PAL), and ammonium acetate (PAAC). When the plants were harvested after 6 weeks, it was observed that most plants had responded to P fertilization with increased leaf tissue P concentrations and DM, but with poor or no correlations to the P levels measured in soil extracts or with the DGT technique. This observation highlighted the importance of pot size relative to the produced biomass in order to avoid the development of extensive P depletion zones surrounding the roots, as it prevented extrapolation of results to the field scale. Consequently, based on interviews with farmers, nine soils which in previous seasons responded to P fertilization, were selected in Denmark (7) and Norway (2). On each location spring barley was cultivated either with or without P fertilization, and soil analyses were regularly compared with the composition of essential plant nutrients in leaf tissue and with the final grain yields. In the field experiments, 30days after establishment (DAE), all four methods could predict P concentrations in the youngest fully emerged leaf (YFEL) of unfertilized plants. Using a Mitscherlich equation on these data, coefficients of determination (R2) ranged from 0.46 to 0.83. The Olsen-P method performed poorest while the DGT method showed the best correlation. However, three weeks later (56 DAE) the soil tests failed to reflect plant available P, as the correlation with leaf P concentrations had disappeared. At harvest, only plants with a leaf P concentration below 2000μgPg−1DM during early vegetative growth (30 DAE) responded to P fertilization by increasing the grain yield. In summary, these observations suggested that a number of significant external factors, which cannot be reflected by DGT or any soil extraction methodology, inherently limit the validity of soils test in predicting the plant availability of P. This includes the inability of soil test to measure P availability in deeper soil layers and physiochemical parameters limiting P diffusion and uptake such as low soil moisture and temperature.

Monitoring the dynamics of wheat stem elongation: genotypes differ at critical stages

Stem elongation is a critical phase for yield formation in wheat (Triticum aestivum). This study proposes the use of terrestrial laser scanning (TLS) for phenotyping of growth dynamics during wheat stem elongation in high temporal resolution and high throughput in the field. TLS was implemented on a novel field phenotyping platform carrying a cable suspended sensor head moveable in 3D over a 1 ha field. Canopy height was recorded on 335 winter wheat genotypes across two consecutive years. Scans were done in 3-d intervals during the stem elongation phase. Per day, 714 plots (two replications plus checks) were scanned within 3.5 h. The results showed that canopy height increased linearly with thermal time. Based on this linearity, 15 and 95% of final height were used as proxy measures for the onset and termination of stem elongation, respectively. We observed high heritability between 0.76 and 0.91 for the onset, termination and duration of stem elongation. The onset of stem elongation showed a positive covariance with the termination of stem elongation and final height indicating some regulatory dependencies. Yet there was no apparent relationship between onset and duration of stem elongation. Due to its precision, the TLS method allows to measure the dynamics of stem elongation in large sets of genotypes. This in turn offers opportunities to investigate the genetic control of the transitions between early vegetative growth, stem elongation and flowering. Understanding the genetic control of these transitions is an important milestone towards knowledge-based crop improvement.

An alternative dormancy-breaking agent to hydrogen cyanamide for sweet cherry (Prunus aviumL.) under low chilling accumulation conditions in the Central Valley of Chile

In areas with mild winters and low chill accumulation, the application of budbreak promoters such a hydrogen cyanamide (HC) is used to overcome insufficient winter chilling in sweet cherry (Prunus avium L.). Despite HC efficiency, its toxicity to human health and environment has become a serious issue. A potential alternative to HC is Erger®, an organic nitrogen compound. Erger® might promote a more concentrated and uniform bloom, early vegetative growth and higher fruit size, without toxic effects. The objective of this study was to compare the effect of applications of Erger® and HC on fruit production and vegetative growth in combination 'Santina®'/'Pontaleb'. The experiment was carried out in Colina (Lat. 33°13'; Long. 70°42'), Metropolitan Region, Chile. The treatments (TR) included: TR1 = Control (H2O); TR2 = Erger® (6%) + calcium nitrate (9%) [Erger®+Ca(NO3)2]; TR3 = Erger® (6%); TR4 = calcium nitrate (9%) [Ca(NO3)2]; TR5 = hydrogen cyanamide (2%) + oil at (0,015%) [HC+oil]. TRs were sprayed with 520 chilling hours (Modified Richardson model). Erger®+Ca(NO3)2 and HC+oil treatments advanced bloom. [Erger®+Ca(NO3)2] concentrated bloom and increased the number extension shoots. Pollen viability was negatively affected by most TRs with exception of Erger®+Ca(NO3)2. Fruit set was similar among TRs. Budbreak promoters increased significantly fruit weight, however, [Erger®+Ca(NO3)2] not only increased fruit size, but it also shifted the distribution curve to the larger sizes.

Nitrogen Use Efficiency of Coffee at the Vegetative Stage as Influenced by Fertilizer Application Method.

Nitrogen (N) is the most limiting nutrient for coffee production in Colombia. An adequate supply is especially important during the vegetative period of growth, since any deficiency during this short period is known to have lasting effects on subsequent coffee bean production. Urea fertilizer is commonly applied on the soil surface since steep slopes hamper incorporation into soil, a practice which increases the risk of N volatilization. Little information is available on N recovery during early growth stages under different fertilizer application practices. The aim of this study was therefore to provide a comparison of 15N uptake during the early vegetative growth stage under surface-applied and incorporation practices at two contrasting locations. The highest proportion of plant N derived from fertilizer (Ndff) occurred 60 days following application at the site with greater precipitation and soil organic matter, where surface application also increased the Ndff in roots and stems after 120 days. Although fertilizer N supplied approximately 20–29% of total plant N after 4 months, this fertilizer-derived N corresponded on average to only 5% of the total application, indicating that very little fertilizer (relative to how much is applied) reaches plants during this time. Apart from the difference in Ndff observed at the wetter site, there was no effect of application method on dry weight and macronutrient content in different plant components, root to shoot ratio, and leaf 13C content. However, site effects were registered for most of these measurements, with the exception of total nutrient uptake. Similarly to Ndff trends, lower root/shoot ratio and higher concentrations of N, K, and Mg in aboveground biomass were found in the site with higher rainfall and soil organic matter, likely resulting from higher soil water and N availability. These findings provide new information useful as a direction for further research looking toward increasing NUE during the vegetative stage in Colombian coffee crops.