Nitrogen Balance Index Research Articles

​Performance of Pigeon Pea [Cajanus cajan (L.) Millsp] Genotypes under Cold Stress

Background: In north India, pigeon pea experiences low temperature stress during winter months (December-January). Information’s regarding cold stress and its impact on morphological characters, physio-biochemical processes and yield attributes in pigeon pea crop is very limited. Keeping the above facts in to consideration, the experiment was formulated to screen suitable genotypes of pigeon pea tolerant to cold stress based on morpho-physiological traits and ability to set flower and pods and yield performance. Methods: Field experiments with 98 genotypes of pigeon pea were conducted in augmented design including checks with all recommended cultural practices in 2018-19 and 2019-20 at New Research Farm, ICAR-IIPR, Kanpur. Morphological, biochemical and yield parameters were recoded periodically. Result: Based on the reaction of pigeon pea genotypes against the exposer of cold stress in terms of flower/pod drop and flower/pod retention, cold injury at the apical meristems and post regeneration of apical portion, the genotypes like IPA 15F, Dhule-D, JBT46/27, IPACT-6, IPACT-14, IPAC-1-17, IPACT-68, IPACT-22 showed greater than 90% flower/pod drop and retained only 0-10% flowers/pods, greater than 90% apical damage and less than 10% recovery of apical portion and were considered highly sensitive to cold stress. Genotypes namely MA-3, IPA 9F, ICP 15-9-1, VKG 27/161, H-26, ICPL 7035, LRG-30, PBT/SSL 2/73, KPL 1034-31, IPA 15-15, KPL 34, ICP 2073, IPACT-5, IPAB 10-66, IPACT-10, IPACT-11, IPAHT-26, IPACT-15, IPAD 2-8, IPACT-16, IPAD-8, IPACT-17, IPAHT-43, IPACT-21 showed greater than 80% flower/pod drop and retained 10-20% flower/pods, greater than 80%apical damage and less than 20% recovery of apical portion and considered moderately susceptible to cold stress. Genotypes NDA-2, MAL-13, ICP-2275, IPACT-2 showed around 20-40% flower/pod drop and have retained 60-80% flowers/pods, less than 20% apical damage and greater than 80% recovery of apical portion were considered as the highly tolerant to cold stress. The nitrogen balance index, chlorophyll and flavonols showed higher values in tolerant group whereas lower in susceptible group. The average yield/plant of pigeon pea genotypes tolerant to cold stress is considerably higher than the susceptible group of pigeon pea genotypes.

Functional and biochemical characteristics of Oxycoccus palustris Pers. under exposure of a gas torch (Khanty-Mansi Autonomous Okrug-Yugra, Russia)

The study was carried out on a sphagnum swamp exposed to thermal radiation from an associated petroleum gas (APG) combustion flare at various distances from the flare stack, which has been operating continuously for more than thirty years. The study was carried out in the period from 2018 to 2019 in the territory of the Pokachevskoye field (Khanty-Mansi Autonomous Okrug-Yugra, Nizhnevartovsk district). Some functional and biochemical characteristics of Oxycoccus palustris Pers were studied. The Oxycoccus palustris Pers. photosynthesis and respiration intensity data analysis, the pigment composition of leaves (chlorophyll and anthocyanins content), the nitrogen balance index (NBI), non-enzymatic antioxidants (flavonoids, proline and ascorbic acid content) were studied, the biochemical composition of leaves specifics (nitrogen, carbon, soluble and non-structural sugars and metals accumulation) were determined in the conditions of exposure to the flare.

Effects of Melatonin on Tomato Infected with Root-knot Nematode Meloidogyne incognita

This study was conducted in 2020 to investigate the influence of melatonin (10, 50 and 100 µM) given in three methods (immersion, irrigation, and foliar spraying) on some physiological aspects of tomato seedlings inoculated with root-knot nematode Meloidogyne incognita [(Kofoid and White) Chitwood]. The seedlings were inoculated with 1000 second-stage juveniles of M. incognita. Dualex® optic sensor was used to in situ measure total chlorophylls, flavonols, anthocyanins contents and nitrogen balance index (NBI). Results indicated that while no significant effects were observed on chlorophyll content, melatonin ameliorated the adverse effects of M. incognita on chlorophyll depending on the concentration and mode of application. Flavonols were at the highest in the irrigated plants and the lowest in the immersed ones. NBI was affected by the method the melatonin was applied, and immersing boosted it while irrigation caused a significant decrease. Irrigation resulted in significantly higher anthocyanins compared to the other two methods. One observation was that applying melatonin in the low and medium concentrations to the soil containing nematode increased the anthocyanin content of the plant. Melatonin merits a value in developing a response against the nematode but needs further elucidation.

All Are in a Drought, but Some Stand Out: Multivariate Analysis in the Selection of Agronomic Efficient Popcorn Genotypes

The search for productive germplasm adapted to adverse conditions is an important action to mitigate the harmful effects of climate change. The aim was to identify the yield potential of 50 popcorn inbred lines grown in field conditions, in two crop seasons (CS), and under contrasting water conditions (WC). Morphoagronomic, physiological, and root system traits were evaluated. Joint and individual analyses of variance were performed, in addition to the multivariate GT bip-lot analysis. Expressive reductions between WC were observed in 100-grain weight (100 GW), popping expansion (PE), grain yield (GY), expanded popcorn volume per ha (EPV), row number per ear (RNE), plant height (PH), relative chlorophyll content (SPAD), and nitrogen balance index (NBI). It was found that the SPAD, 100 GW, GY, PE, and grain number per ear (GNE) traits had the most significant impact on the selection of genotypes. Regardless of WC and CS, the ideal lines were L294 and L688 for PE; L691 and L480 for GY; and L291 and L292 for both traits. SPAD, 100 GW, and GNE can contribute to the indirect selection. Our work contributes to understanding the damage caused by drought and the integration of traits for the indirect selection of drought-tolerant popcorn genotypes.

Woody invaders from contrasted climatic origins distribute differently across the urban-to-rural gradient in oceanic Europe – Is it trait-related?

Alien plant species invasion depends on biotic and abiotic conditions that can represent environmental barriers as compared to their native range conditions. Specifically, little is known about how alien plant species distribute along the urban-to-rural gradients based on their native climatic conditions, and how environmental conditions along these gradients could influence intraspecific trait variation. We studied the distribution of eight woody alien plant species from contrasted native range climates along urban-to-rural gradients in European areas with a temperate climate (hereafter termed oceanic Europe). During two consecutive summers and in the Belgian part of oceanic Europe, we then measured their intraspecific trait variation using the nitrogen balance index (NBI), chlorophyll content, flavonols index, specific leaf area (SLA) and internode space. Urban-to-rural gradients were characterized by a system of local climate zones (LCZ), the percentage of artificially sealed surfaces (urbanity) and the sky view factor (SVF). We found that the distribution of studied species in the LCZ classes was highly dependent on the climate of their native range, with species from warm climates occurring more in the most urban areas while the ones from cool climates preferred the more rural or natural areas. However, their intraspecific trait variation was not related to the LCZ class in which they grew, nor to their native climate. Instead, we found a surprisingly consistent effect of shielded environments (low SVF) along the entire urban-to-rural gradient on leaf and development traits. Such environments induced a lower leaf flavonols index and higher NBI and SLA, suggesting a shade response and possibly lower heat and drought stress. Our results show that although woody alien plant species from warmer or cooler native climates distributed differently along the urbanization gradient in oceanic Europe, they did not show contrasted intraspecific trait variation. Nevertheless, our findings highlight that even if the woody alien plant species from cooler native ranges are currently more present in the most natural areas, special attention should be paid to woody alien plant species from warmer native ranges that are yet restricted to the most urban areas and could potentially have severe impacts in the future when the barriers to their spread weaken with climate change.

Nitrogen Balance Index Prediction of Winter Wheat by Canopy Hyperspectral Transformation and Machine Learning

Nitrogen balance index (NBI) is an important indicator for scientific diagnostic and quantitative research on crop growth status. The quick and accurate assessment of NBI is necessary for farmers to make timely N management decisions. The objective of the study was to estimate winter wheat NBI based on canopy hyperspectral features between 400–1350 nm combined with machine learning (ML) methods in the individual and whole growth stages. In this study, 3 years of winter wheat plot experiments were conducted. Ground-level canopy hyperspectral reflectance and corresponding plant NBI values were measured during the jointing, booting, flowering and filling stages. Continuous removal spectra (CRS) and logarithmic transformation spectra (LOGS) were derived from the original canopy spectra. Sensitive bands and vegetation indices (VIs) highly correlated with NBI under different spectral transformations were selected as hyperspectral features to construct the NBI estimation models combined with ML algorithms. The study indicated that the spectral transformation significantly improved the correlation between the sensitive bands, VIs and the NBI. The correlation coefficient of the sensitive band in CRS in the booting stage increased by 27.87%, reaching −0.78. The leaf chlorophyll index (LCI) in LOGS had the highest correlation with NBI in the filling stage, reaching a correlation coefficient of −0.96. The NBI prediction accuracies based on the sensitive band combined with VIs were generally better than those based on the univariate hyperspectral feature, and the prediction accuracy of each growth stage was better than that of the whole growth stage. The random forest regression (RFR) method performed better than the support vector regression (SVR) and partial least squares regression (PLS) methods. The NBI estimation model based on the LOGS-RFR method in the filling stage could explain 95% of the NBI variability with relative prediction deviation (RPD) being 3.69. These results will provide a scientific basis for better nitrogen nutrition monitoring, diagnosis, and later for field management of winter wheat.

Low- and High-Temperature Phenotypic Diversity of Brassica carinata Genotypes for Early-Season Growth and Development.

Temperature is a major abiotic stress factor limiting plant growth and development during the early developmental stage. Information on carinata (Brassica carinata A. Braun) traits response to low and high temperatures is necessary for breeding or selecting genotypes suited for specific ecoregions, which is limited. In the present study, 12 carinata genotypes were evaluated under low (17/09°C), optimum (22/14°C), and high (27/19°C) day/night temperatures at the early developmental stage. This study quantified temperature effects on several physiological and morphological characteristics of 12-advanced carinata lines. High-temperature plants decreased (15%) the accumulation of flavonoids and increased the nitrogen balance index by 25%. Low-temperature treatment significantly inhibited the aboveground (plant height, leaf area, number, and shoot weight) and root (length, surface area, and weight) traits. Across all genotypes, the shoot weight decreased by 55% and the root weight by 49% under low temperature. On the other hand, the maximum proportion of biomass was partitioned to roots under low temperature than at the high temperature. A poor relationship (r2 = 0.09) was found between low- and high-temperature indices, indicating differences in trait responses and tolerance mechanisms. AX17004 and AX17009 with higher root to shoot ratios might be suitable for late planting windows or regions with low-temperature spells. The two genotypes (AX17015 and AX17005) accumulated higher biomass under low- and high-temperature treatments can be used for planting in later summer or early winter. The identified low- and high-temperature stress-tolerant carinata genotypes could be a valuable resource for increasing stress tolerance during the early developmental stage.

Leaf Functional Traits of Invasive Grasses Conferring High-Cadmium Adaptation Over Natives

Heavy metal (HM) contamination resulting from industrialization and urbanization during the Anthropocene along with plant invasion can severely threaten the growth and adaptation of local flora. Invasive alien plant species generally exhibit a growth pattern consistent with their functional traits in non-contaminated environments in the introduced range. However, it remains unclear whether invasive alien plants have an advantage over native plants in contaminated environments and whether this growth pattern is dependent on the adaptation of their leaf functional traits. Here, we selected two congeneric pairs of invasive alien and native grasses that naturally co-exist in China and are commonly found growing in contaminated soil. To evaluate the effect of cadmium (Cd) on the structural and physiological leaf traits, we grew all four species in soil contaminated without or with 80 mg/kg Cd. Invasive plants contained significantly higher concentrations of Cd in all three organs (leaf, stem, and root). They displayed a higher transfer factor and bioconcentration factor (BCF) of shoot and root than natives, indicating that invasive species are potential Cd hyperaccumulators. Invasive plants accumulated polyphenol oxidase (PPO) to higher levels than natives and showed similar patterns of leaf structural and physiological traits in response to changes in Cd bioconcentration. The quantifiable leaf structural traits of invasive plants were significantly greater (except for stomatal density and number of dead leaves) than native plants. Leaf physiological traits, chlorophyll content, and flavonoid content were also significantly higher in invasive plants than in natives under Cd stress conditions after 4 weeks, although nitrogen balance index (NBI) showed no significant difference between the two species. Chlorophyll fluorescence parameters decreased, except for the quantum yield of photosystem II (ΦPSII) and the proportion of open photosystem II (qP), which increased under Cd stress conditions in both species. However, invasive plants exhibited higher fluorescence parameters than natives under Cd stress, and the decrement observed in invasive plants under Cd stress was greater than that in natives. High Cd adaptation of invasive grasses over natives suggests that invasive plants possess optimal leaf structural and physiological traits, which enable them to adapt to stressful conditions and capture resources more quickly than natives. This study further emphasizes the potential invasion of alien plants in contaminated soil environments within the introduced range. To a certain extent, some non-invasive alien plants might adapt to metalliferous environments and serve as hyperaccumulator candidates in phytoremediation projects in contaminated environments.

Evaluation of the growth, storage root yield, proximate composition, and mineral content of colored sweet potato genotypes

The storage roots and leaves of sweet potato are potential sources of human nutrition. Variations may exist in the growth, yield, and nutritional contents of different genotypes. In this experiment, the growth, storage root yield, yield-contributing traits, leaf chlorophyll (Chlo) index, anthocyanin (Antho) index, flavonoid (Flavo) index, nitrogen-balance index (NBI), proximate compositions, and mineral content of the leaves and storage roots of sweet potato genotypes were investigated to identify nutrient-rich and high-yielding sweet potato. A field experiment was performed using the randomized complete block design, and a laboratory analysis was conducted using the completely randomized design with three replicates. Significant variations were observed in the growth, yield-contributing traits, yield of storage roots, leaf indices, proximate compositions, and mineral content of both organs of sweet potato genotypes. The range of the different components were as follows: storage root yield, 2.04 ± 0.18 t/ha to 48.80 ± 12.06 t/ha; dry matter contents of the storage roots and leaves, 20.26%–35.16%, and 10.24%–16.68%, respectively; leaf Chlo index, 27.25 ± 2.12 to 34.51 ± 0.71; Flavo index, 1.10 ± 0.12 to 1.59 ± 0.05; and Antho index, 0.18 ± 0.02 to 0.21 ± 0.03. Except nitrogen-free extract (NFE) and starch, the proximate compositions and mineral contents were higher in leaves than in storage roots. The mineral content of leaves were 0.80% ± 0.01%–1.29% ± 0.03% calcium (Ca), 0.24% ± 0.01%–0.40% ± 0.01% magnesium (Mg), 5.25% ± 0.02%–6.96% ± 0.04% phosphorus (P) and 1.22% ± 0.01%–1.41% ± 0.01% potassium (K). From the findings of this study, it was indicated that leaves are a good source of protein, fiber, and minerals particularly Ca, Mg, P, and K. Thus, storage roots including sweet potato leaves can be consumed to combat malnutrition, particularly in low income groups in developing countries. • Significant variation existed between the yield-contributing traits and yield of storage roots of sweet potato genotypes • Leaf chlorophyll, and flavonoid indices are substantially diverse among sweet potato genotypes • Sweet potato leaves are a vital source of protein, fiber, and minerals, particularly Ca, Mg, P, and K

The content of photosynthetic pigments in the leaves of «healthy» and «weakened» balsam poplar trees (<i>Populus balsamifera</i> L.) growing under conditions of industrial pollution (Republic of Bashkortostan, Sterlitamak industrial center)

The paper presents the results of studies on the assessment of the relative vitality of balsam poplar ( Populus balsamifera L.) plantations under the conditions of polymetallic pollution of the Sterlitamak Industrial Center (SIC). Poplar plantations of the sanitary protection zone of the SPC are classified as weakened. External signs of oppression are manifested in a decrease in crown density, an increase in the number of dead branches, damage to the assimilation apparatus by chlorosis and necrosis. Trees belonging to the healthy category grow in the plantations. It was shown that the average content of chlorophylls ( a + b ) in the leaves of healthy poplar trees varied from 25,0 to 28,0 g/cm of fresh weight, while in weakened trees it was relatively low and amounted to 17,2-22,6 g/cm wet weight. The decrease in the total content of chlorophylls and the deterioration in the relative vitality of trees are interrelated. It has been established that during the period of active leaf growth (in June and early July), a high content of chlorophylls and nitrogen balance index (NBI) is noted in the leaves of both healthy and weakened balsam poplar trees. The relationship of the indicators under consideration is confirmed by the regression equations of the polynomial function ( y = -2,15x + 8,05x + 23,2 ; y = -2,35x + 8,75x + 19,9 for the leaves of healthy trees; y = -3,1x + 11,1x +13,4 ; y = -3,9x + 14,1x + 10 for the leaves of weakened trees), as well as determination coefficients (R = 1 for the leaves of healthy trees; R = 1 for the leaves of weakened trees). The maximum differences in the ratio of chlorophyll content ( a + b ) and nitrogen balance in the leaves of healthy and weakened poplar trees were noted at the end of August. During the growing season, in the leaves of weakened trees, compared with the leaves of healthy poplar trees, a decrease in the values NBI and the content of chlorophylls is observed. At the same time, there are no significant changes in the content of chlorophylls on the adaxial and abaxial sides of the leaves of healthy and weakened balsam poplar trees during the growing season.

Composted Solid Digestate and Vineyard Winter Prunings Partially Replace Peat in Growing Substrates for Micropropagated Highbush Blueberry in the Nursery

The “soilless” cultivation of blueberry (Vaccinium corymbosum L.) in containers with peat as substrate allows overcoming the problem of unsuitable soils, thus enhancing the spread of this crop in new areas. Since the use of peat presents several critical environmental and economic sustainability issues, the evaluation of alternative solutions is required. The effectiveness of compost produced with solid digestate and residues from the vine-wine chain to replace part of the peat was therefore tested. Micropropagated plants of cultivar Duke grown in three substrates consisting of a mixture of commercial peat with three compost fractions (10, 20, 40%) were compared with plants grown in 100% unfertilized or fertilized peat (0.3 g of Osmocote per pot). Plant height did not significantly differ between the five theses at the end of the trial, whereas the total number of nodes per plant was higher than in the control theses, due to a greater development of secondary shoots. The nutritional status of the plants, monitored with Dualex, during the growing season, was generally not significantly different in the innovative substrates compared to peat alone. In mid-summer the plants grown in substrates with compost showed the best nitrogen balance index (NBI values). Plants cultivated with medium-high percentages of compost (20–40%) showed a lower degree of defoliation at the end of the trial, dependent on a slower decline of vegetative activity. The final destructive measures of fresh and dry weight of biomass and of its partitioning between roots and shoots highlight that the use of compost did not negatively affect the production of biomass, but rather, in the theses with the highest percentages of compost (20–40%), root development was stimulated.

Winter Wheat Nitrogen Estimation Based on Ground-Level and UAV-Mounted Sensors.

A better understanding of wheat nitrogen status is important for improving N fertilizer management in precision farming. In this study, four different sensors were evaluated for their ability to estimate winter wheat nitrogen. A Gaussian process regression (GPR) method with the sequential backward feature removal (SBBR) routine was used to identify the best combinations of vegetation indices (VIs) sensitive to wheat N indicators for different sensors. Wheat leaf N concentration (LNC), plant N concentration (PNC), and the nutrition index (NNI) were estimated by the VIs through parametric regression (PR), multivariable linear regression (MLR), and Gaussian process regression (GPR). The study results reveal that the optical fluorescence sensor provides more accurate estimates of winter wheat N status at a low-canopy coverage condition. The Dualex Nitrogen Balance Index (NBI) is the best leaf-level indicator for wheat LNC, PNC and NNI at the early wheat growth stage. At the early growth stage, Multiplex indices are the best canopy-level indicators for LNC, PNC, and NNI. At the late growth stage, ASD VIs provide accurate estimates for wheat N indicators. This study also reveals that the GPR with SBBR analysis method provides more accurate estimates of winter wheat LNC, PNC, and NNI, with the best VI combinations for these sensors across the different winter wheat growth stages, compared with the MLR and PR methods.

Mycorrhiza improves plant growth and photosynthetic characteristics of tea plants in response to drought stress

Tea plants are sensitive to soil moisture deficit, with the level of soil water being a critical factor affecting their growth and quality. Arbuscular mycorrhizal fungi (AMF) can improve water and nutrient absorption, but it is not clear whether AMF can improve the photosynthetic characteristics of tea plants. A potted study was conducted to determine the effects of Claroideoglomus etunicatum on plant growth, leaf water status, pigment content, gas exchange, and chlorophyll fluorescence parameters in Camellia sinensis cv. Fuding Dabaicha under well-watered (WW) and drought stress (DS) conditions. Root mycorrhizal colonization and soil hyphal length were significantly reduced by the eight-week DS treatment. AMF inoculation displayed a significant increase in shoot and root biomass production. The relative water content, leaf water potential, nitrogen balance index, pigment content, maximum photometric effect (Fv/Fm, QY_max), and steady-state photometric effect Y (II) (QY_Lss) decreased dramatically, while the leaf water saturation deficit and steady-state non-photochemical fluorescence quenching (NPQ_Lss) generally increased under DS conditions. Mycorrhizal treatment induced significantly higher relative water content, leaf water potential, nitrogen balance index, pigment (chlorophyll, flavonoid, and anthocyanin) content, net photosynthesis rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, QY_max, and QY_Lss; however, it resulted in a lower leaf water saturation deficit and NPQ_Lss under both WW and DS conditions, as compared with non-mycorrhizal plants. These results imply that AMF promoted tea plant growth and alleviated negative effects of DS by promoting gas exchange, regulating the water status of leaves, and regulating photosynthetic parameters.

Stimulate® e acadian® promovem incremento no crescimento e índices fisiológicos de mudas de Hymenaea courbaril ?

Abstract Products that have biostimulant action on forest seedlings, such as those based seaweed Acadian® and hormones, have been used due to their beneficial effect on the physiology and growth of plants, in order to improve the quality of forest seedlings. The present study establishes as research problem: Can doses of Acadian® algae extract and Stimulate® be effective for the initial growth and physiological indices of jatobá seedlings? The variables evaluated were: shoot height (H), stem diameter (SD), increments in stem diameter (?SD) and shoot height (?H), shoot dry mass (SDM, g plant-1), root dry mass (RDM, g plant-1) and total dry mass (TDM, g plant-1), and Dickson quality index, net assimilation rate (EA, g.m-2.day), leaf relative growth rate (RA, g.m-2.day), leaf area ratio (FA, m2.g-1), specific leaf area (SA, cm2.g-1), leaf mass ratio (Fw, g/g-1) as well as nitrogen balance index (NBI) and chlorophylls. The plant growth regulators (Acadian®) at the dose of maximum technical efficiency of 0.28 ml L-1 promotes an increase in stem diameter in Hymenaea courbaril. Acadian® increases chlorophyll a and b contents in Hymenaea courbaril seedlings. The tested doses of Stimulate® do not increase chlorophyll a and b contents in H. courbaril seedlings.

Understanding the Impact of Vertical Canopy Position on Leaf Spectra and Traits in an Evergreen Broadleaved Forest

Little attention has been paid to the impact of vertical canopy position on the leaf spectral properties of tall trees, and few studies have explored the ability of leaf spectra to characterize the variation of leaf traits across different canopy positions. Using a tower crane, we collected leaf samples from three canopy layers (lower, middle, and upper) and measured eight leaf traits (equivalent water thickness, specific leaf area, leaf carbon content, leaf nitrogen content, leaf phosphorus content, leaf chlorophyll content, flavonoid, and nitrogen balance index) in a subtropical evergreen broadleaved forest. We evaluated the variability of leaf traits and leaf spectral properties, as well as the ability of leaf spectra to track the variation of leaf traits among three canopy layers for six species within the entire reflectance spectrum. The results showed that the eight leaf traits that were moderately or highly correlated with each other showed significant differences along the vertical canopy profile. The three canopy layers of leaf spectra showed contrasting patterns for light-demanding (Castanopsis chinensis, Castanopsis fissa, Schima superba, and Machilus chinensis) and shade-tolerant species (Cryptocarya chinensis and Cryptocarya concinna) along the vertical canopy profile. The spectra at the lower and upper canopy layers were more sensitive than the middle layer for tracking the variation of leaf chlorophyll and flavonoid content. Our results revealed that it is important to choose an appropriate canopy layer for the field sampling of tall trees, and we suggest that flavonoid is an important leaf trait that can be used for mapping and monitoring plant growth with hyperspectral remote sensing.

Monitoring nitrogen variability in two Mediterranean ornamental shrubs through proximal fluorescence-based sensors at leaf and canopy level

Over - fertilization is one of the most relevant issues affecting container-grown nursery plants.The massive application of chemicals results in severe pollution due to nitrogen (N) leaching, and leads to the production of unhealthy plants sensitive to fungal diseases and insect attacks that increase the use of pesticides. The ability of two fluorescence-based sensors (Dualex and Multiplex) for assessing the N-sufficiency of container grown Prunus laurocerasus L. and Ligustrum japonicum L. as test plants was investigated in a two-year long experiment under experimental and commercial growing conditions. An optimal N rate of 450 mg L−1 was identified for both species growing under different N fertilization levels (0 - 1350 mg N L−1). Fluorescence-based indices allowed for reliable estimation of both chlorophyll and nitrogen content at the leaf and canopy level. Absolute and relative sufficiency threshold values were provided and spatially compared under standard nursery conditions. The optimal shoot N concentration of 2.04% (P. laurocerasus) and 1.35% (L. japonicum), and the corresponding non-destructive nitrogen balance index (NBI) values were assessed and used for decision-making on N application and monitoring of the species considered.

Influence of 24-Epibrassinolide on Physiological Characteristics of Tomato Seedlings Infested with Root-knot Nematode Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 (Tylenchida: Meloidogynidae)

The aim of this research is to determine the physiological responses of tomato seedlings treated with 24-epibrassinolide (EBL), given via different methods such as immersion, irrigation, and foliar spray, followed by inoculation of root-knot nematode Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 (Tylenchida: Meloidogynidae). Physiological measurements (chlorophyll, flavonols, nitrogen balance index, and anthocyanins) were carried out non-destructively with a portable chlorophyll meter at the end of the 56th days post inoculation. Results showed that chlorophyll contents of the tomato leaves were affected by both the EBL applications and the methods, and that they were better protected with the irrigation method. Flavonols and nitrogen balance index were inversely related with the method. Leaf anthocyanin index was affected just by the EBL applications. Depending on the physiological aspect under observation, the method (immersion against irrigation, for instance) might present a challenging status in terms of evoking protection against root-knot nematode when tomato plants are treated with EBL.

The Impact of LED Light Spectrum on the Growth, Morphological Traits, and Nutritional Status of ‘Elizium’ Romaine Lettuce Grown in an Indoor Controlled Environment

The study examined the influence of light quality on the growth and nutritional status of romaine lettuce grown in deep water culture with a floating raft system using two different nutrient solutions. Four spectra of LED light were used with different ratios of R, G, and B lights (80:10:10, 70:10:20, 60:10:30, and 70:18:12). Two nutrient solutions with a low (A) and moderately high (B) nutrient content were used. Regardless of the nutrient solution, the RGB 70:18:12 light promoted the production of leaf biomass as well as inhibited the accumulation of K and Mg in the leaves. Moreover, those plants were characterized by a low Nitrogen Balance Index (NBI) and a high flavonol index. In the last week of cultivation, there was a strong decrease in K, P, and nitrates in the nutrient solution, and an increase in Ca. In the final stage of growth, symptoms of withering of the tips of young leaves (tipburn) were observed on the plants. The most damage was observed on the plants growing under 70:10:20, 70:18:12, and with the higher concentration of minerals in the solution (B).

Drought and Elevated Carbon Dioxide Impact the Morphophysiological Profile of Basil (Ocimum basilicum L.)

Treating plants with elevated carbon dioxide (eCO2) can increase their drought tolerance. Increased atmospheric CO2, a fundamental factor in climate change, may compensate for the drought-induced reduction in crop growth and yield. Basil, being moderately sensitive to drought stress (DS), experiences several morphological changes under DS. Thus, we designed an experiment that addresses how DS and different levels of CO2 affect the overall morphological growth patterns during basil’s early and late-season growth. The experiment was conducted under four different growth conditions: two water treatments, (1) a full-strength Hoagland’s solution was added to the basil plants at 120% of the evapotranspiration each day, and (2) 50% of the full-strength Hoagland’s solution was added to basil plants for the drought treatment, alongside two levels of CO2 application [ambient 420 ppm (aCO2) and elevated 720 ppm (eCO2)]). The DS had a severe impact on the morphological traits of the shoot and root systems. Compared to control, DS reduced the marketable fresh mass (FM) by 31.6% and 55.2% in the early and late stages of growth. FM was highest under control + eCO2 (94.4–613.7 g) and lowest under DS + aCO2 (67.9–275.5 g). Plant height under DS + aCO2 and DS + eCO2 reduced by 16.8% and 10.6% during the late season. On the other hand, dry mass percent (DM%) increased by 31.6% and 55.2% under DS + eCO2 compared to control in the early and late stages of growth, respectively. This study suggested that eCO2 during DS significantly impacts basil morphological traits compared to aCO2. Besides, anthocyanin decreased by 10% in DS + aCO2 and increased by 12.6% in DS + aCO2 compared to control. Similarly, nitrogen balance index, a ratio of chlorophyll and flavonoids, was recorded to be the highest in DS + aCO2 (40.8) compared to any other treatments. Overall, this study indicates that the suppression of basil’s morphophysiological traits by DS is more prominent in its later growth stage than in the earlier stages, and eCO2 played an important role in alleviating the negative effect of DS by increasing the DM% by 55%.

Morpho-Physiological Traits and Functional Markers Based Molecular Dissection of Heat-Tolerance in Urdbean.

Urdbean (Vigna mungo L. Hepper) is one of the important pulse crops. Its cultivation is not so popular during summer seasons because this crop is unable to withstand excessive heat stress beside lack of humidity in the atmosphere. Therefore, a panel of 97 urdbean diverse genotypes was assessed for yield under stress and non-stress conditions with an aim to identify heat tolerant genotypes. This study identified 8 highly heat tolerant and 35 highly heat sensitive genotypes based on heat susceptibility index. Further, physiological and biochemical traits-based characterization of a group of six highly heat sensitive and seven highly heat tolerant urdbean genotypes showed genotypic variability for leaf nitrogen balance index (NBI), chlorophyll (SPAD), epidermal flavnols, and anthocyanin contents under 42/25°C max/min temperature. Our results showed higher membrane stability index among heat tolerant genotypes compared to sensitive genotypes. Significant differences among genotypes for ETR at different levels of PAR irradiances and PAR × genotypes interactions indicated high photosynthetic ability of a few genotypes under heat stress. Further, the most highly sensitive genotype PKGU-1 showed a decrease in different fluorescence parameters indicating distortion of PS II. Consequently, reduction in the quantum yield of PS II was observed in a sensitive one as compared to a tolerant genotype. Fluorescence kinetics showed the delayed and fast quenching of Fm in highly heat sensitive (PKGU 1) and tolerant (UPU 85-86) genotypes, respectively. Moreover, tolerant genotype (UPU 85-86) had high antioxidant activities explaining their role for scavenging superoxide radicals (ROS) protecting delicate membranes from oxidative damage. Molecular characterization further pinpointed genetic differences between heat tolerant (UPU 85-86) and heat sensitive genotypes (PKGU 1). These findings will contribute to the breeding toward the development of heat tolerant cultivars in urdbean.