Leaf Count Research Articles

Anxiety in Duckweed–Metabolism and Effect of Diazepam on Lemna minor

The fate of pharmaceuticals in the human body, from their absorption to excretion is well studied. However, medication often leaves the patient’s body in an unchanged or metabolised, yet still active, form. Diazepam and its metabolites, ranging up to 100 µg/L, have been detected in surface waters worldwide; therefore, the question of its influence on model aquatic plants, such as duckweed (Lemna minor), needs to be addressed. Lemna was cultivated in a Steinberg medium containing diazepam in three concentrations—0.2, 20, and 2000 µg/L. The activity of superoxide dismutase (SOD) and catalase (CAT), leaf count, mass, and the fluorescence quantum yield of photosynthesis were assessed. The medium was also analysed by LC-MS/MS to determine the concentration of diazepam metabolites. Our results show no negative impact of diazepam on Lemna minor, even in concentrations significantly higher than those that are ecotoxicologically relevant. On the contrary, the influence of diazepam on Lemna suggests growth stimulation and a similarity to the effect diazepam has on the human body. The comparison to the human body may be accurate because γ-Aminobutyric acid-like (GABA-like) receptors responsible for the effect in humans have also been recently described in plants. Therefore, our results can open an interesting scientific area, indicating that GABA receptors and interference with benzodiazepines are evolutionarily much older than previously anticipated. This could help to answer more questions related to the reaction of aquatic organisms to micropollutants such as psychopharmaceuticals.

PHYTOREMEDIATION OF IRON CONTAMINATED SOIL BY WATERLEAF (Talinum triangulare (Jacq) Willd) IN JOS, PLATEAU STATE, NIGERIA

Phytoremediation is an environmentally friendly approach which involves plants for removal ofcontaminants from polluted soil. The objective of this study therefore was to evaluate theeffectiveness of water leaf (Talinum triangulare) in extraction of iron (Fe) from contaminatedsoil. The research consisted of the following treatments: 0, 26, 52, 78, 104, 130 and 156 Femg/kg of soil. Iron nitrate was used as the source of iron. The plant data collected were leaf andflower count, plant height, stem diameter, number of branches, shoot weight, the root weight andiron concentration in the shoot. These were analyzed using analysis of variance and the Fisher’spairwise comparisons. The result showed that there was no significant effect of treatments ongrowth parameters except for leaf count. Plants that received 130 (Fe mg/kg) had significantlyhigher leaf count probably due to higher amount of nitrogen supplied by iron nitrate. There wassignificance difference in iron concentration in the shoots of water leaf plants among the varioustreatments when compared to the control. Mean maximum extraction of iron was 5815 mg/kgwith a standard deviation of 16.51. Lower leaf count and amounts of iron extracted at higherconcentration of iron in the soils are probably due to unset of iron toxicity in the water leaf plants.This indicates that water leaf plants possess great potential in phyto-extraction of iron and otherheavy metals from contaminated soil.

Landscape and stand-scale factors drive the infestation of an endemic fungal pathogen: The role of leaf traits

Endemic plant pathogens are important agents of many forest processes and contribute to shaping forest ecosystem dynamics and diversity. However, Marssonina leaf spot of poplar is induced by a pathogenic fungus Drepanopeziza populi, causing increased damage to riparian poplars in recent years. And such endemic diseases have received little attention at the landscape scale, despite the key role of landscape features in the development and spread of certain emerging diseases. Moreover, few studies have sufficiently captured multiple ecological factors driving the infestation of an endemic pathogen acting at the landscape, stand, and individual scales. Here, we measured pathogen load, disease prevalence, and disease severity of Marssonina leaf spot in bitter poplars (Populus laurifolia) in riparian forests, and explored the direct and indirect effects of multiple ecological factors on pathogen infestation using structural equation models. Specifically, we first assessed the effects of landscape and stand-scale factors on leaf traits including leaf area, specific leaf area (SLA), and leaf dry matter content (LDMC), and then examined the role of these factors in shaping disease dynamics. We found that forest cover had no direct impact on host leaf traits and pathogen infestation, but directly affected stand characteristics, with higher forest cover in a landscape increasing host density and tree diversity. Host density was the most important factor of pathogen load, with a higher density of host poplars resulting in greater symptomatic leaf count. Tree diversity had direct effects on disease prevalence, with host poplars growing in mixed forest stands far less infected by pathogens than in pure stands. Disease prevalence was also positively related to pathogen load. Moreover, tree diversity strongly reduced SLA but increased LDMC. Leaves with higher SLA was found to increase pathogen load and disease severity, but leaves with higher LDMC was found to reduce them. Our results show that landscape-scale forest cover indirectly affects Marssonina leaf spot dynamics via stand characteristics and leaf traits. Disentangling the effects of biotic and abiotic factors on pathogen infestation can provide crucial insights into multi-scale ecological factors in driving plant disease expression, and contribute to reducing the overall impact of endemic forest diseases.

Do invasive species provide a refuge from browsers? A test of associational resistance in a peri-urban habitat plagued by deer

White-tailed deer (Odocoileus virginianus) overbrowsing over the past several decades has caused substantial changes to plant communities in eastern deciduous forests. Deer-preferred species have declined or become locally extirpated in many areas while deer-tolerant species have greatly increased in abundance. Moreover, the abundance of nonnative invasive species has also increased over the last few decades, outcompeting many native species. Native shrubs such as Sambucus canadensis (American elderberry) are now much less common, particularly in urban forests and forests with high deer densities. Here, we performed a short-term study in which we introduced propagations of a native shrub into a replicated field experiment in which we factorially manipulated deer presence or absence and invasive species presence or absence by using exclosures and removing invasive species. We monitored metrics of S. canadensis fitness including leaf count and plant height over two growing seasons. Browsing substantially reduced survival whereas invasive species provided a modest degree of associational resistance. Browsing significantly decreased both leaf count and plant height. By the end of the study, individuals within exclosures had over twice the number of leaves, were five times taller, and had much lower mortality versus those exposed to browsing. Removing invasive species did not change plant height, however, S. canadensis individuals experienced marginally higher leaf counts inside exclosures where we had removed invasive species. This trend was opposite in individuals outside of fences such that those growing within patches where invasive species remained had slightly higher leaf counts, especially during the first growing season. Until the final census date, elderberry growing within patches of invasive species had slightly lower mortality versus those growing in patches where invasive species had been removed. The results from our short-term study indicate that browsing is more inimical to a native shrub than competition from invasive species and we did not find evidence of associational resistance to browsing from invasive cover.

Agronomic Yield Performance of Rape and Assessment of Discrimination of Soil Fertilizer Amendments on Genotypic Responses

Aim: The objectives of the study were to (i) assess agronomic performance of rape (Brassica napus L.) genotypes under different soil amendments and seasons and (ii) identify the most discriminating soil fertilizer amendment on genotypic responses of rape.
 Study Design: The experiment was laid as a split plot design with 3 replications in each season.
 Place and Duration of Study: The study was undertaken in Monze district, southern province, Zambia in winter and summer periods of 2020/2021 cropping season.
 Methodology: The soil fertilizer amendment combinations were the main plots and rape varieties (English Giant [ENG], Hobson [HOB] and Rampart [RAM]) were laid as subplots. Giving a total of 54 experimental units per season. The amendments constituted combinations of raw dung type and artificial fertilizer. The quantitative data, on biomass, breadth, height and leaf count were measured at six weeks after transplanting.
 Results: Across seasons, soil amendment and genotypic main effects exhibited significantly responses with regards to biomass and leaf count (P = 0.05). Furthermore, the agronomic genotypic performance showed that RAM was the worst performer. The genotypic response to measured agronomic parameters was better in Raw Cow-Dung plus Cow- Dung Ash (RCD + CDA) soil fertilizer amendment than others. Interestingly RCD + CDA was the common discriminating amendment in summer and winter trials.
 Conclusion: Rape genotypes performed relatively better in summer than in winter season. The genotype English giant rape and Hobson were better performers across seasons and soil fertilizer amendments. The combination of RCD + CDA was the common discriminating amendment in both summer and winter trials.

Competitive Interactions between Two Non-Native Species (Alliaria petiolata [M. Bieb.] Cavara & Grande and Hesperis matronalis L.) and a Native Species (Ageratina altissima [L.] R.M. King & H. Rob.).

Alliaria petiolata and Hesperis matronalis are wide-ranging non-native species in North America. Ageratina altissima is native to North America but has become a concern as an invasive species in Asia. A replacement series experiment was established to quantify the competitive interactions between these three species and to rank their relative competitiveness with each other. We assessed leaf count, chlorophyll content, and aboveground biomass with comparisons between replacement series mixtures and competition species. Overall leaf count and aboveground biomass were greatest in A. altissima and chlorophyll content was lowest in A. petiolata. Chlorophyll content and aboveground biomass were lower for A. altissima in competition with A. petiolata compared to H. matronalis. Leaf count for A. petiolata was lower in competition with A. altissima compared to H. matronalis. Aboveground biomass for H. matronalis was lower in competition regardless of the species compared to monoculture. There were also negative trends in biomass for A. petiolata in competition with increasing neighbors. However, for A. altissima, the negative trend in biomass was with A. petiolata, H. matronalis did not negatively affect A. altissima biomass. Our rank order of competitiveness was A. altissima > A. petiolata >> H. matronalis.

Eff-UNet++: A novel architecture for plant leaf segmentation and counting

Leaf segmentation learns more about leaf-level traits such as leaf area, count, stress, and development phases. In plant phenotyping, segmentation and counting of plant organs like leaves are a major challenge due to considerable overlap between leaves and varying environmental conditions, including brightness variation and shadow, blur due to wind. Further, the plant's inherent challenges, such as the leaf texture, genotype, size, shape, and density variation of leaves, make the leaf segmentation task more complex. To meet these challenges, the present work proposes a novel method for leaf segmentation and counting employing Eff-Unet++, an encoder-decoder-based architecture. This architecture uses EfficientNet-B4 as an encoder for accurate feature extraction. The redesigned skip connections and residual block in the decoder utilize encoder output and help to address the information degradation problem. In addition, the redesigned skip connections reduce the computational complexity. The lateral output layer is introduced to aggregate the low-level to high-level features from the decoder, which improves segmentation performance. The proposed method validates its performance on three datasets: KOMATSUNA dataset, Multi-Modality Plant Imagery Dataset (MSU-PID), and Computer Vision for Plant Phenotyping dataset (CVPPP). The proposed approach outperforms the existing state-of-the-art methods UNet, UNet++, Residual-UNet, InceptionResv2-UNet, and DeeplabV3 leaf segmentation results achieve best dice (BestDice): 83.44, 71.17, 78.27 and Foreground-Background Dice (FgBgDice): 97.48, 91.35, 96.38 on KOMATSUNA, MSU-PID, and CVPPP dataset respectively. In addition, for leaf counting the results are difference in count (DiffFG): 0.11, 0.03, 0.12 and Absolute Difference in count (AbsDiffFG): 0.21, 0.38, 1.27 on KOMATSUNA, MSU-PID, and CVPPP dataset respectively.

GROWTH RATES OF PARKIA biglobosa JACQ. SEEDLINGS (AFRICAN LOCUST BEAN TREE) AS INFLUENCED BY TWO INORGANIC MANURES

One of the prominent fruit trees in the savanna ecosystem is Parkia biglobosa Jacq. (African Locust Bean Tree). Apart from being a nitrogen fixing tree, the seeds from its matured pods are often processed and used as soup condiment in some African countries most especially Nigeria. The population density of this plant species is low, its growth rate is slow and the processed seeds are not abundantly available and therefore costly. Thus, the influence of two inorganic manures/fertilizers (Urea and N. P. K.) on the growth rate of the seedlings of this species was investigated to pave way for massive production. The experimental design employed was completely randomized design (CRD) comprising 3 treatments and 4 replicates (treatments A (sandy loam + Parkia biglobosa seeds + N.P.K), B (sandy loam + Parkia biglobosa seeds + Urea) and C (sandy loam + Parkia biglobosa seeds as control). Seedlings’ emergence rates/percentages and morphological growth indices /parameters (plant height, leaf count, number of branches, collar girth and leaf area) were evaluated. Application of inorganic manures commenced at the 6th week after germination/seedling emergence. Results from statistical data analyses (SPSS 21.0) indicated significant differences (at P≤0.05) among the treatments. Seedlings in Urea + sandy loam (treatment B) had the highest mean values/fastest growth rate followed by treatment A and treatment C was the least. Incontrovertibly, faster growth rate of this important tree species could be achieved by employing Urea and relatively, N.P.K fertilizer could also be used.

Effect of Certain Types and Doses of Organic Manures on Seed Germination and Seedling Growth of Foxglove (Digitalis purpurea L.) at Temperate Hill Ranges of Bharsar, Uttarakhand

In a study of response of foxglove (Digitalis purpurea L.) to different types and doses of organic manures namely, FYM, compost and vermicompost, it was seen that vermicompost @ 15 t ha-1 consistently witnessed to provide superior performances in all the traits under study like quickest germination (4 days), highest germination per cent (77.33%). Also, tallest plant height (8.63 cm), longest leaf length (6.64 cm), maximum leaf count per plant (9.26), widest plant spread (11.22 cm), total fresh and dry biomass (2.73 g plant-1 and 0.71 g plant-1, respectively), widest leaf area (15.36 cm2), longest root length (10.80 cm) and highest root diameter (1.67 mm) were being recorded in vermicompost @ 15 t ha-1 at 90 DAS and were found statistically significant.

Cotton maturity and responses to harvest aids following chemical topping with mepiquat chloride during bloom period

Early maturity, complete defoliation and boll opening are essential for the efficient machine harvesting of cotton. Chemical topping, involving one extra application of mepiquat chloride (MC) in addition to its traditional multiple-application strategy, may be able to replace manual topping. However, it is not known whether this chemical topping technique will influence maturity or cotton responses to harvest aids. In this 2-yr field study, we determined the effects of the timing of chemical topping using various rates of MC on boll opening percentage (BOP) before application of harvest aids (50% thidiazuron·ethephon suspension concentrate, referred to as TE), and the defoliation percentage (DP) and BOP 14 days after TE application. The results indicated that late chemical topping (near the physiological cutout, when the nodes above white flower is equal to 5.0) significantly decreased BOP before TE by 5.9–11.2% compared with early (at peak bloom) or middle (seven days after peak bloom) treatments in 2019, which was a relatively normal year based on crop condition. Also, a high MC rate (270 g ha−1) showed a significantly lower (22.0%) BOP before TE than low (90 g ha−1) or medium (180 g ha−1) rates. In 2020, which was characterized by stronger vegetative growth in the late season, the late chemical topping reduced the number of leaves before TE application relative to early or middle treatments, but had lower DP (23.2–27.2%) 14 days after TE application. The high MC rate showed a leaf count before TE application that was similar to the low and medium rates, but it showed the most leaves after TE and much lower (15.0–21.7%) DP in 2020. These results suggest that late timing of chemical topping and a high MC rate decreased the sensitivity of leaves to harvest aids. Further analysis indicated that the late chemical topping mainly affected the leaf drop from the mainstem and fruiting branches where the late regrowth occurred, and the high MC rate reduced leaf shedding from these parts and also from the vegetative branches. In conclusion, chemical topping with MC during the bloom period affected cotton maturity and responses to harvest aids in different ways according to the crop condition. To avoid the risks of delayed maturity and poor defoliation after the application of harvest aids, chemical topping should not be performed too late (i.e., near the physiological cutout) by using MC at more than 180 g ha−1. The optimum timing of chemical topping probably varies from peak bloom to around seven days later, and the safest MC rates for chemical topping should be less than 180 g ha−1.

Rice-husk biochar effects on organic carbon, aggregate stability and nitrogen-fertility of coarse-textured Ultisols evaluated using Celosia argentea growth

There are insufficient data supporting the enormous potential of biochar in highly weathered tropical soils. This glasshouse study assessed rice-husk biochar (RHB) effects on soil organic carbon, aggregate stability and nitrogen fertility of sandy-loam Ultisols which were evaluated using spinach (<em>Celosia argentea</em>) growth. Five RHB rates 0, 5, 10, 20, and 40 g per two-kg-soil (0, 7.5, 15, 30 and 60 t ha<sup>−1</sup>, respectively) were studied under 0, 4, 8, and 12 weeks of incubation (WOI). Batched potting of treatments enabled sowing on one date. Treatment effects on soil quality were assessed at sowing and spinach growth six weeks later. Soil organic carbon generally increased with RHB rate, with the greatest increments (37%) in maximum rate relative to no-biochar control for 8 WOI. Aggregate stability also generally increased with RHB rate, the range being 7.21%-17.21% for 8 WOI, beyond which it decreased in 10 and 20 but not 40 g pot<sup>–1</sup>. Total nitrogen was always highest in maximum rate, increasing with rate only for 8 WOI. Treatment affected plant height more clearly than leaf count. Optimum rates were 5 or 10 g pot<sup>–1</sup> for 8 and 4 WOI, respectively (plant height) and 10 g pot<sup>–1</sup> for 8 WOI (leaf count). Soil organic carbon influenced soil aggregate stability (R<sup>2</sup> = 0.505) which in turn was quadratically related to plant height (R<sup>2</sup> = 0.517), indicating stability threshold for spinach. Adding RHB at 40 g pot<sup>–1</sup> (≈ 60 t ha<sup>−1</sup>) to coarse-textured tropical soils is suggested to sustain its soil aggregating effect beyond the growth phase of short-cycle leafy vegetables which require a lower rate (10 g pot<sup>–1</sup>) 8 weeks before sowing. The observed role of soil aggregate stability in spinach growth rather than the overall effects of RHB should guide further search for edapho-agronomic optimum rate of RHB.

Effect of Carbonized Tangerines Prepared Using Plasma as Fertilizer: Case Study—Lettuce Farming

This study investigates the soil chemical changes and crop growth characteristics after treatment with carbonized tangerines prepared using plasma. To determine the effect of the carbonized tangerines on crop, four test plots were treated with chaff charcoal or different ratios of coco peat and carbonized tangerines. Lettuce was grown on the plots, and the chemical changes in soil and physical changes in the lettuce were observed. Chemical changes in the soil before and after the carbonized tangerine treatments were very similar to those before and after chaff charcoal treatment. Lettuce leaf length, width, weight, and count in carbonized tangerine-treated plots significantly increased than those in the untreated plot. Our results found that the carbonization of tangerines using plasma can be a good alternative for processing many by-products generated during cultivation. In addition, the possibility of using carbonized tangerines as biochar has been explored.

Influence of Different Herbicide Based Weed Management Practices on Growth and Yield of Flue Cured Tobacco in Northern Light Soils of Andhra Pradesh, India

Flue cured tobacco requires clean and weed free environment and thereby reduce the competition for nutrients and moisture for achieving quick early season growth. Deploying effective weed management practices play a key role in achieving better yields and quality. Field experiments were conducted at Peddpauram village of West Godavari district (Andhra Pradesh) during (Rabi) seasons of 2018-19 and 2019-20, to study the effect of different herbicide based weed management practices on growth and yield of flue cured Tobacco crop. The experiment was performed as Randomized Block Design with 11 weed management practices replicated thrice. The results recorded on growth parameters, in both the years revealed that six inter cultivations with two manual removal of weeds significantly impacted plant height (113.5 cm and 114.4 cm) and leaf area index (2.63 and 2.83) at 90 DAT over Imazethapyr applied at 0.05 kg a.i ha-1. Number of leaves plant-1 were higher with six inter cultivation and two manual removal of weeds (21.5 and 20.6) over Imazethapyr 0.05 kg a.i ha-1. Inter cultivations and manual weeding resulted in significantly enhancing yield attributes such as leaf thickness (0.143 mm and 0.143 mm for cutters and 0.183 mm and 0.173 for leaf) and lower leaf count (Number of leaves kg-1) (137 and 129) over weedy check. Application of Sulfentrazone 0.03 kg a.i ha-1 was comparable with inter cultivation and manual weeding. Sulfentrazone 0.3 kg a.i ha-1 contributed for significantly higher yield (2302 kg ha-1 and 2424 kg ha-1) over weedy check and comparable with six inter cultivations and two manual weeding operations. The application of pre emergence herbicides like Pendimethalin, Alachlor and Oxyflurfen resulted achieving higher yield levels over the application of post emergence herbicides such as Quiazalofop-p-ethyl, Fenoxaprop ethyl, Carfentrazone ethyl and Imazethapyr during both years of experimentation.

Browse from Three Tree Legumes Increases Forage Production for Cattle in a Silvopastoral System in the Southwest Amazon.

Assessing the palatability of forage from locally adapted trees could improve the sustainability of livestock production systems. However, grasses continue to dominate livestock feed across the Amazon. We established a silvopastoral cattle farming system in Peru, comparing three different forage tree species with grass monocultures using a randomised block design. Trees were arranged in alleys of 0.5 × 7.5 m, planted alongside grass, and were directly browsed by cattle. Browse removal was estimated by three methods: destructive sampling, canopy measurements and leaf counts. We found that all three tree species were palatable to cattle. Plots containing trees and grass produced more available forage (mean > 2.2 Mg ha-1) for cattle than the grass monocultures (mean = 1.5 Mg ha-1). Destructive sampling below 1.6 m demonstrated that cattle consumed 99% of the available Erythrina berteroana forage, 75% of the available Inga edulis forage and 80% of the available Leucaena leucocephala forage in 8 days. This research demonstrates methodologies to estimate the intake of locally adapted browse species by cattle and highlights the potential benefits of silvopastoral systems in the Amazon. Planting trees could also benefit animal health and provide ecosystem services such as soil regeneration, enhanced nutrient cycling and carbon capture.

Improvement on the Growth Performance of Parkia biglobosa Seedlings (African Locust Bean Tree) Using Inorganic Fertilizers.

Parkia biglobosa (African locust bean tree) is one of the wild fruit trees in the savanna ecosystem and it is characterized with slow growth rate. The fruits are edible and very popular in western Nigeria and to some extent in other regions. Sequel to the slow growth rate of this plant, this study employed application of some inorganic fertilizers (Urea and N. P. K.) to possibly improve the growth rate of the seedlings of Parkia biglobosa. The design of the experiment is completely randomized design (CRD) consisting of three treatments and four replicates (treatment A: sandy loam + Parkia biglobosa seeds + N.P.K, B: sandy loam + Parkia biglobosa seeds + Urea and C: sandy loam + Parkia biglobosa seeds as control). The parameters investigated were seedlings’ emergence rates and percentages and morphological growth parameters (plant height, leaf count, number of branches, collar girth and leaf area). Inorganic fertilizer application commenced 6 weeks after seedling emergence. The data collected were subjected to statistical analysis of variance which revealed significant differences (P≤0.05) among the treatments. Treatment B had the highest mean values, followed by A and C was the least. Thus, Urea and N.P.K fertilizers could be employed in improving the growth rate of this important tree species. Keywords: Wild fruits, Parkia biglobosa, inorganic fertilizers, early growth rate, morphological, parameters.

A soil‐nesting invasive ant disrupts carbon dynamics in saplings of a foundational ant–plant

Abstract Nearly every terrestrial ecosystem hosts invasive ant species, and many of those ant species construct underground nests near roots and/or tend phloem‐feeding hemipterans on plants. We have a limited understanding of how these invasive ant behaviours change photosynthesis, carbohydrate availability and growth of woody plants. We measured photosynthesis, water relations, carbohydrate concentrations and growth for screenhouse‐reared Acacia drepanolobium saplings on which we had manipulated invasive Pheidole megacephala ants and native Ceroplastes sp. hemipterans to determine whether and how soil nesting and hemipteran tending by ants affect plant carbon dynamics. In a field study, we also compared leaf counts of vertebrate herbivore‐excluded and ‐exposed saplings in invaded and non‐invaded savannas to examine how ant invasion and vertebrate herbivory are associated with differences in sapling photosynthetic crown size. Though hemipteran infestations are often linked to declines in plant performance, our screenhouse experiment did not find an association between hemipteran presence and differences in plant physiology. However, we did find that soil nesting by P. megacephala around screenhouse plants was associated with >58% lower whole‐crown photosynthesis, >31% lower pre‐dawn leaf water potential, >29% lower sucrose concentrations in woody tissues and >29% smaller leaf areas. In the field, sapling crowns were 29% smaller in invaded savannas than in non‐invaded savannas, mimicking screenhouse results. Synthesis. We demonstrate that soil nesting near roots, a common behaviour by Pheidole megacephala and other invasive ants, can directly reduce carbon fixation and storage of Acacia drepanolobium saplings. This mechanism is distinct from the disruption of a native ant mutualism by P. megacephala, which causes similar large declines in carbon fixation for mature A. drepanolobium trees. Acacia drepanolobium already has extremely low natural rates of recruitment from the sapling to mature stage, and we infer that these negative effects of invasion on saplings potentially curtail recruitment and reduce population growth in invaded areas. Our results suggest that direct interactions between invasive ants and plant roots in other ecosystems may strongly influence plant carbon fixation and storage.

Temperature impact on the influence of penguin-derived nutrients and mosses on non-native grass in a simulated polar ecosystem.

Human activity and climate change are increasing the spread of species across the planet, threatening biodiversity and ecosystem functions. Invasion engineers, such as birds, facilitate plant growth through manuring of soil, while native vegetation influences plant germination by creating suitable microhabitats which are especially valuable in cold and dry polar regions. Here we tested how penguin‐derived nitrogen, several common Antarctic moss species and warming affect seed germination and growth of the non‐native grass Agrostis capillaris under laboratory conditions. Experimental settings included a simulation of contemporary season‐specific Antarctic light and temperature (2°C) conditions and a +5°C warming scenario. Mosses (Andreaea depressinervis, A. regularis, Sanionia uncinata and Chorisodontium aciphyllum) incorporated a range of nitrogen content and isotopic nitrogen signatures (δ15N) due to variation in sampling proximity to penguin colonies. Moss species greatly affected time to germination with consequences for further growth under the simulated Antarctic conditions. Grass seeds germinated 10 days earlier among A. regularis compared to S. uncinata and C. aciphyllum and 26 days earlier compared to A. depressinervis. Moss‐specific effects are likely related to microclimatic differences within the moss canopy. Warming reduced this moss influence. Grass emerged on average 20 days earlier under warming, leading to increased leaf count (88%), plant height (112%) and biomass (145%). Positive correlations were identified between moss and grass nitrogen content (r = 0.377), grass biomass (r = 0.332) and height (r = 0.742) with stronger effects under the warming scenario. Transfer of nitrogen from moss to grass was confirmed by δ15N (r = 0.803). Overall, the results suggest a shift from temperature‐limited to N‐limited growth of invasive plants under increased warming in the maritime Antarctic.

Intercropping with Guiera senegalensis in a semi‐arid area to mitigate early‐season abiotic stress in A. hypogea and P. glaucum

AbstractRecent research has shown that the native shrub, Guiera senegalensis J.F. Gmel, interplanted with crops dramatically increases crop yield in the Sahel. However, little is known about the crop development when grown alongside shrubs. The objectives were to determine the effect of shrub presence on crop development under varying fertilizer rates in northern Senegal. Peanut (Arachis hypogaea L.) and pearl millet (Pennisetum glaucum (L.)) response in the presence or absence of shrubs was investigated from 2013 to 2016 under low to adequate rainfall. The experiment had a split‐plot factorial design with presence or absence shrubs (+shrub, −shrub) as the main plot (elevated densities of 1200 to 1500 shrubs ha−1) and fertilizer rate (0, 0.5, 1 or 1.5 times the recommended N–P–K rate) as the subplot factors. Major developmental phases, leaf counts and plant height were determined. Shrub presence made crops grow up to four times taller and reach 50% flowering when −shrub plots did not reach 50% in 2013 and 2015 (millet). Changes to crop development, even in low rainfall years, indicate that shrub intercropping buffers against crop water stress. Thus, under drought conditions, shrub‐based agroforestry can contribute to reduce fertilizer necessity and to mitigate against climate change.

Bridging the gap: linking morpho-functional traits' plasticity with hyperaccumulation.

Plant species exhibiting heavy metal tolerance are instrumental in phytoremediation of metalliferous sites. Most of the time, variations in plant functional traits (PFTs) are overlooked while identifying hyperaccumulators. However, investigating morphological, physiological, and phenological variations can contribute to our knowledge about stress tolerance, and aid in identifying potential hyperaccumulators. In the present study, we investigated variation in morpho-functional traits in Solanum nigrum, a known hyperaccumulator, under lead (Pb) stress. Twenty-one PFTs including 9 above-ground (leaf count, leaf area, specific leaf area, leaf dry matter content, leaf thickness, leaf dry mass, shoot length, stem dry mass, stem diameter), 3 below-ground (root length, root dry mass, and root diameter), 4 reproductive (flower bud count, fruit count, flower count, and fruit dry mass), and 5 photosynthetic traits (total chlorophyll, total carotenoid, chlorophyll a, chlorophyll b, and photosynthetic efficiency) under varying Pb concentrations (500-2000mgkg-1) were assessed. Pillai's trace test (MANOVA) depicted significant variations in above-ground, below-ground, and photosynthetic traits, whereas reproductive traits did not vary significantly with progressive metal concentration. However, most of the studied traits except flower count, fruit dry mass, and chlorophyll b varied significantly under Pb stress. The study depicts that enhanced PFT's plasticity enables S. nigrum to grow in Pb-contaminated soil effectively without impacting plant fitness. Plasticity of morpho-functional traits, therefore, establishes itself as a resourceful approach in successful identification of phytoremediation capacity of a plant.

Morphology and yield potential of sweet potato (Ipomoea batatas L.) as influence by NPK fertilizer rates and vine cutting length in Jos Plateau State, Nigeria

The experiment was carried out in the demonstration farm of Federal College of Forestry Jos during the 2019 farming season to determine the effects of NPK fertilizer rates and vine cutting lengths on the growth and yield of sweet potato. The treatments include, three rates of NPK fertilizer (0, 0.2 and 0.4 kg) allocated to the main plot and two vine cutting lengths of (30 and 40 cm) in the sub plot in 3 x 2 factorial split plot design. The parameters assessed includes; number of branches, length of vine, leaf count, leaf area index and vine girth at 2, 4, 6, 8 and 10 weeks after fertilizer application (WAFA) and tuber count, tuber length, and yield weight at harvest. The parameters were subjected to analysis of variance and the means separated using the LSD (Least significant difference) at (p≤0.05). The results on the number of branches shows significant difference at 2 and 6 (WAFA) and at 4 WAFA for both treatments and positive interaction at 8 WAFA. Vine length showed no statistical difference at 4 WAFA, but significance at 2 and 8 WAFA with positive interaction at same weeks. The results on leaf count showed significance across the weeks with fertilizer rates and at 2 WAFA with vine cuttings with no interactions across the trend. The leaf area index showed no statistical difference with all the treatments as indicated. The vine girth showed significant difference across the weeks with fertilizer rates, and at 10 WAFA with the vine cuttings with no interactions. The yield parameters showed significance and positive interaction across with both treatments on tuber count, tuber weight and tuber length respectively. In conclusion, these results indicated that planting sweet potato in Jos plateau with a fertilizer rates of (0.4 kg/2m2 experimental plot) and 40 cm vine length could impact the growth and yield positively.