Plant Populations Research Articles

Dryland pea seeding rates can be reduced without yield or economic penalty

AbstractMontana is the leading producer of field peas (Pisum sativum L.) in the United States. A density of 8 to 10 plants ft−2 is recommended when growing field peas in that state, but this recommendation is based on work done elsewhere. Field experiments were conducted in central Montana from 2021 through 2023 and at three additional locations in the final year to determine the yield and the economically optimum plant population (EOPP) when growing field peas for grain. The semi‐leafless, yellow‐cotyledon variety Montech 4152 was planted at five rates (5, 7, 9, 11, and 13 pure live seed [PLS] ft−2) in all 3 years with two additional rates (3 and 15 PLS ft−2) added in the final year. A minimum plant density of 6 to 8 plants ft−2, or planting field pea at 7 to 9 PLS ft−2, produced a grain yield comparable to or greater than amounts produced at other seeding rates. The minimum EOPP across the six experiments ranged from 3 (2.8) to 7 (6.4) plants ft−2, corresponding to a seeding rate of 3 to 7 PLS ft−2. However, more weeds were observed when field pea was planted at 3 PLS ft−2 than at higher rates in one of the experiments. A field pea density of 6 to 8 plants ft−2 is sufficient to optimize grain yield and economic returns in Montana and similar dryland environments.

Response of Yield of Shallot (<i>Allium ascalonium</i> L.) to Nitrogen Fertilizer Rates and Spacing Under Irrigation at Mulo, Ethiopia

The shallot (<i>Allium ascalonium</i> L.) is one of the important alliaceous crops cultivated in many tropical countries. It is an important horticultural crop used to flavor the local stew "wot" and a source of income for farmers in Ethiopia. However, the productivity of shallot is low at study area due to various limiting factors such as low soil fertility, plant population and lack of improved agronomic practices. A field experiment was conducted to investigate the effect of intra-row spacing and nitrogen fertilizer levels on growth, yield and quality of shallot at Mulo District, Oromia Regional state, Ethiopia during 2021/22 off season. The treatments consisted of four intra-row spacing (5, 10, 15 and 20) cm and four levels of nitrogen fertilizer (0, 50, 100 and 150) kgNha<sup>-1</sup> tested in a randomized complete block design with three replications. Data on shallot yield was collected. The interaction effect of intra-row spacing and nitrogen fertilizer influenced the marketable yield, unmarketable yield, bulb weight, bulb fresh weight, bulb dry weight, dry matter and total yield. As a result, the treatment combination of 150kgha<sup>-1</sup> nitrogen and 15cm intra-row spacing yielded the highest net benefit of shallot (Eth-Birr 1,012,274), followed by the treatment combination of 150kgha<sup>-1</sup> nitrogen and 20 cm intra-row spacing. In conclusion, the above findings indicated that the combined application of 150kgNha<sup>-1</sup> with 15 cm spacing can improve shallot growth and productivity in the Mulo district area. However, more research needs to be done in different seasons and locations, taking into account the application rate of nitrogen fertilizer and different intra-row spacing, to generate more reliable information.

Intraspecific diversity mitigates the negative soil-legacy impacts of an invasive plant.

Elton's biotic resistance hypothesis predicts that biodiversity can resist the establishment of invasive plants. However, whether and how within-species diversity mediates the impacts of successfully established invaders is poorly understood, particularly in the face of climate change. We used an experimental system to test the effect of intraspecific diversity of a native foundation species, Scirpus mariqueter, on the soil-legacy impacts of a global plant invader, Spartina alterniflora, under well-watered and drought conditions. We found that more diverse populations of the native plant buffered against the negative soil-legacy impacts of the invader on the native plant. This intraspecific diversity effect was due to a complementarity effect triggered by invader-shaped soil biota, and emerged in both well-watered and drought conditions. Compared with the previous finding that intraspecific diversity of the native plant can reduce the performance of the invader through soil biotic feedbacks, this study provides further evidence that it helps to mitigate the negative soil-derived impacts of the invader. These findings together emphasize the need for management measures that promote and restore native intraspecific diversity in a changing world.

Masting ontogeny: the largest masting benefits accrue to the largest trees.

Both plants and animals display considerable variation in their phe- notypic traits as they grow. This variation helps organisms to adapt to specific challenges at different stages of development. Masting, the variable and synchronized seed production across years by a population of plants, is a common reproductive strategy in perennial plants that can enhance reproductive efficiency through increasing pollination efficiency and decreasing seed predation. Masting represents a population-level phenomenon generated from individual plant behaviors. While the developmental trajectory of individual plants influences their masting be- havior, the translation of such changes into benefits derived from masting remains unexplored. We used 43 years of seed production monitoring in European beech (Fagus sylvatica) to address that gap. The largest improvements in reproductive efficiency from masting happen in the largest trees. Masting leads to a 48-fold reduction in seed predation in large, compared to 28-fold in small trees. Masting yields an 6-fold increase in pollination efficiency in large, compared to 2.5-fold in small trees. Paradoxically, although the largest trees show the biggest reproductive efficiency benefits from masting, large trees mast less strongly than small trees. That apparently suboptimal allocation of effort across years by large plants may be a consequence of anatomical constraints or bet-hedging. Ontogenetic shifts in individual mast- ing behavior and associated variable benefits have implications for the reproductive potential of plant populations as their age distribution changes, with applications in plant conservation and management.

Human Activity Changed the Genetic Pattern of the Orchid Phaius flavus Population

Human activity often has profound effects on plant growth and evolution. Orchids are the most diverse group of flowering plants and are threatened by habitat fragmentation, over-harvesting, and urbanization. A population of Phaius flavus from Beikengding Mount (BM) in the Fujian Province of China was divided into two patches by road construction. This study evaluated its genetic characteristics using restriction site-associated DNA sequencing (RAD-seq) data, more than seven years post-road construction. The purpose of this study was to explore the impact of road construction on the evolution of isolated patches within a population. The analysis revealed that the genetic diversity of patch B was slightly higher than that of patch A in the BM population of P. flavus. Principal component and phylogenetic analyses, genetic structure and genetic differentiation analysis, and bottleneck detection indicated relatively independent genetic differentiation between the two patches. Thus, the construction of the Y013 village road may have influenced different patches of this population on a genetic level. This study provides a case for understanding the impact of specific human activities on plant populations, and then biodiversity conservation. It is conducive to formulating more effective biological protection strategies to mitigate the damage inflicted by human activities on biodiversity.

Morphological Diversity of “Tuni” and “Afo” Cloves, Endemic to the Maluku Islands, Indonesia

“Tuni” and “Afo” cloves are endemic clove varieties from the Maluku islands. Until now, there is still little information on morphological diversity in plant populations and information on the characteristics between the two varieties. The research aims to provide information on the morphological diversity and characteristics of “Tuni” and “Afo” cloves from the Maluku Islands. Morphological characterization of the “Tuni” variety of cloves was carried out at its distribution location on Ambon Island, Maluku Province. In contrast, “Afo” cloves were characterized at their distribution location on Ternate Island, North Maluku Province. The research was carried out in July 2023-May 2024. The used for morphological identification was the modified Tropical Fruit Descriptors. The characterized clove plants consisted of 30 “Tuni” clove plants and 30 “Afo” clove plants, so a total of 60 plants were characterized. The results of the Hierarchical Cluster Analysis (HCA) based on 54 morphological characters that were carried out showed two groups with a dissimilarity coefficient of 44%. The first group is a group of “Tuni” clove accessions, which are clustered with a similarity of 91%, and the second group is a group of “Afo” clove accessions, which are clustered with a similarity of 90%. The results of Principle Component Analysis (PCA) obtained a total diversity of 75.4%, where the specific characteristics of “Tuni” cloves obtained were stem bark color, crown shape, branching angle, leaf thickness, old leaf color, shoot color, leaf petiole tip color, flower stalk weight, flower length, flower tube diameter. The specific characteristics of “Afo” cloves obtained from PCA are plant height, stem circumference, North-South canopy width, East-West canopy width, leaf length, leaf texture, leaf spiciness, ripe picked flower color, picked ripe flower crown color, ripe fruit color, and color seed.

Agronomic adaptations to heat stress: Sowing summer crops earlier

CONTEXTSummer crops are exposed to heat and drought stresses at critical stages during and after flowering, and their intensity and frequency are likely to increase with climate change. Agronomic stress avoidance offers the opportunity to temporally separate critical crop stages from heat and drought events. However, it might require sowing cold-sensitive summer crops earlier into colder than recommended soil temperatures. There is a need to understand how cold is too cold to sow summer crops early in late winter as well as what are the yield benefits and risks. OBJECTIVEHere, we quantify the likely benefits and trade-offs of sowing sorghum, a summer cereal, earlier to adapt to the increased frequency and intensity of heat and water stresses during flowering and grain filling. METHODSTwo years of multi-environment (n=32) genotype by management trials were conducted across the main sorghum growing regions of Australia. Environments (E) consisted of the combination of years, sites, three times of sowing (early, spring, and summer), and the use of supplementary irrigation. At each E a factorial combination of four plant populations (M) and eight commercial sorghum hybrids (G) were sown with three replications. Crop growth and yield components were measured, and the APSIM model was used to simulate all trials and treatments to quantify risks and derive insights into functional relationships between simulated and measured environmental covariates, and measured crop traits. RESULTSThe tested hybrids showed small differences in cold tolerance during crop establishment. Across the tested environments, the G×M combinations produced up to 60% variation in treatment yields across environment yields, which varied between <0.5 to about 10t ha-1; this translated into a ~5.5-fold variation in water use efficiency. Significant G×E and M×E interactions were observed for grain yield components. No G×M or G×E×M interactions were observed on yield or yield components. Early sowing was associated with a reduced risk of heat stress and water use transfer from vegetative to reproductive stages. Early sowing in late winter or early spring resulted in no significant yield gain or loss when all sites and years were included in the analysis. However, early sowing yielded between 1-2 t ha-1 more when the hottest sites and years were considered separately. This resulted from both the avoidance of heat stresses and milder or no terminal drought stresses. CONCLUSIONSEarly sowing of sorghum can reduce the likelihood of heat stresses around flowering as well as the likelihood of terminal drought stresses. Advantages include reduced yield losses in the hottest years and a transfer of water use to grain filling stages, resulting in increased grain yield and improved grain quality parameters. IMPLICATIONSEarly sowing, an agronomic adaptation, offers the opportunity to quickly adapt to the increase in the frequency and intensity of extreme hot events during critical crop stages. However, for the practice to be de-risked, there is a need to increase cold and chilling tolerance in sorghum and/or identify interventions that enhance seed germination and seedling vigour when the crop is sown early into cold soils.

Genetic and Habitat Rescue Improve Population Viability in Self-Incompatible Plants.

Habitat fragmentation and the acceleration of environmental change threaten the survival of many plant species. The problem is especially pronounced for plant species with self-incompatibility mating systems, which are obligate outcrossers, thus requiring high mate availability to persist. In such situations, plant populations suffering decreased fitness could be rescued by: (a) improving local habitat conditions (habitat rescue), (b) increasing the number of individuals (demographic rescue), or (c) introducing new genetic variation (genetic rescue). In this study, we used a spatially and genetically explicit individual-based model to approximate the demography of a small (N = 250) isolated self-incompatible population using a timescale of 500 years. Using this model, we quantified the effectiveness of the different types of rescues described above, singly and in combination. Our results show that individual genetic rescue is the most effective type of rescue with respect to improving fitness and population viability. However, we found that introducing a high number of individuals (N > 30) to a small population (N = 50) at the brink of extinction through demographic rescue can also have a positive effect on viability, improving average fitness by 55% compared to introducing a low number of individuals (N = 10) over a long timescale (> 500 years). By itself, habitat rescue showed the lowest effects on viability. However, combining genetic and habitat rescue provided the best results overall, increasing both persistence (> 30%) and mate availability (> 50%). Interestingly, we found that the addition of even a small number of new S alleles (20%) can be highly beneficial to increase mate availability and persistence. We conclude that genetic rescue through the introduction of new S alleles and an increase in habitat suitability is the best management strategy to improve mate availability and population viability of small isolated SI plant populations to overcome the effects of demographic stochasticity and positive density dependence.

Logistics Structure Analysis for Selayar Tangerine Supply Chain Mapping

Citrus fruits are in demand not only for their freshness, but also for their fiber content as nutrients and vitamins, especially vitamin C and vitamin A, which are beneficial for health. Selayar Islands Regency is a citrus development area in South Sulawesi Province. The citrus crop developed in Selayar Islands Regency is the tangerine variety. Along with the development of the citrus plant area, the population of citrus plants in Selayar Islands Regency increases every year. This study aims to describe the mapping of the Selayar tangerine supply chain structure through logistics cost analysis to map the distribution of income between supply chains. The number of respondents in this study was 45 people. This research uses descriptive analysis with convenience and snowball sampling methods to get an objective picture. This research uses logistics cost analysis using the Activity Based Costing method. The results showed that the levels involved in the supply chain are farmers, collectors, wholesalers, small traders, and consumers. The results of the logistics cost calculation show material handling costs as the highest cost of the entire Selayar tangerine supply chain cost.

Phylogeography of Pleurospermum foetens (Apiaceae) From the Sky Islands of Southwest China.

Sky islands provide insights on how glacial-interglacial cycles have shaped species distribution and help for predicting species' responses to climate warming. The alpine subnival belt of southwest China, especially in the Hengduan Mountains and adjacent areas, is sky island-like. Among them, the Yunnan-Kweichow Plateau harbors several isolated mountains with well-developed alpine subnival vegetation, sharing a similar species composition with the Hengduan Mountains. However, the relationship between the sky islands of the Hengduan Mountains and the Yunnan-Kweichow Plateau remains insufficiently explored. Pleurospermum foetens (Apiaceae) is a species endemic to the alpine screes of the Yunnan-Kweichow Plateau and the Hengduan Mountains. We used DNA sequence data from 59 individuals across 9 populations, combined with ecological niche modeling, to investigate the evolution history and future distribution of P. foetens within this sky island region. The results indicate the following: (1) P. foetens exhibits a significant phylogeographic structure and can be classified into three nrDNA clades and two cpDNA clades, respectively, (2) a nuclear-plastid discordance observed in P. foetens and its relatives based on phylogenetic analysis. P. foetens is monophyletic in the nrDNA phylogeny, while two major clades (HDM and YGP) are present in the cpDNA phylogeny, each forming a clade with other congeneric species. (3) Ecological niche modeling of P. foetens indicated that the species had the most extensive suitable habitat during the last glacial maximum (LGM). However, anticipated climate warming in the coming decades is expected to reduce the suitable range of P. foetens, posing a significant threat to isolated marginal populations (e.g., Shizi Mountain) with restricted alpine scree habitats. In conclusion, our study highlights the substantial effect of sky island and glacial-interglacial cycles on the population divergence of P. foetens. Conservation efforts for marginal populations of alpine plants in the Yunnan-Kweichow Plateau require increased attention and prioritization.

Effect of In Vitro Pretreatment with Ag-Containing Amino Acid Nanofibers on Biometrics and Antioxidant Activity in Drought-Stressed Ex Vitro-Adapted Stevia rebaudiana Bertoni

Biotechnological methods prevent the destruction of natural populations of medicinal plants due to climate change and developing agriculture. This study evaluates the effects of in vitro pretreatment with two types of silver-containing amino acid nanofibers (NF-1%Ag and NF1-Ag salt) on the drought tolerance of ex vitro soil-adapted Steviia rebaudiana Bertoni. The duration of the drought was five days. The data suggested that the pretreatment with the studied nanofibers during plant propagation enhanced the plant tolerance to drought stress manifested in a smaller decrease in plant biomass accumulation and a smaller increase in sugar content. The pretreatment with the two tested nanoparticles of well-watered plants increased the leaf fresh biomass accumulation of the ex vitro-adapted S. rebaudiana compared to the untreated WW control plants. The highest values were reported at 10 mg L−1 NF1-Ag salt. Five days of drought led to a decrease in the leaf fresh biomass compared to the WW plants, with the recorded lowest reduction again at 10 mg L−1 NF1-Ag salt. These observations correlate with antioxidant activity improvement. The results show that adding 10 mg L−1 NF1-Ag salt to the MS medium led to higher ex vitro-adapted S. rebaudiana resistance to water deficit than 100 mg L−1. This paper discusses the impact of the selected nanofibers on parameters characterizing plant growth and antioxidant activity of drought-stressed ex vitro-adapted Stevia rebaudiana plants.

Historical increases of maize leaf area index in the US Corn Belt due primarily to plant density increases

ContextLeaf area index (LAI) and leaf area distribution within the maize plant are important traits used to explain and predict light interception and thus crop productivity. ObjectivesHere we investigate breeding and plant density effects of leaf area traits. Our objectives are to 1) quantify maize breeding impacts on leaf area distribution and determine bell-shape coefficients used in crop modeling, 2) dissect the contribution of breeding from plant density, and 3) explore the relationship between LAI and crop yields. MethodsWe studied 18 hybrids released between 1983 and 2017 at two density treatments: current (8.5 pl m-2) and historical increasing density (from 4.6 to 8.5 pl m-2) in Iowa, USA. ResultsResults indicated that concurrent changes in hybrids and increases in plant density have increased LAI from 3.4 (in 1983) to 5.9 m2 m-2 (in 2017), with the highest LAI increases (>50%) to be realized in the middle canopy. At historical increasing in plant density treatment, the LAI increased by 1.6% year-1, but the individual plant leaf area decreased by 0.33% year-1 from 1983 to 2017. This trade-off indicates that new hybrids are more tolerant to higher plant populations than old hybrids. At current plant density treatment, the year of hybrid release did not affect LAI or individual plant leaf area. New hybrids had 5% narrower leaf area distributions, 23% higher optimum LAI values (5.2 vs 4.2 m2 m-2) and 19% higher grain yields compared to old hybrids. ConclusionsThe main reason for the increase in maize LAI in the US Corn Belt is plant density. However, an increase in LAI does not necessarily translate to higher grain yields as new hybrids had significantly higher grain yields than older hybrids at similar LAI values. Present results contribute to our understanding of maize canopy architecture and allow us to better calibrate crop models to accurately estimate LAI and grain yield.

The Current Phyto-Scape and Foodplants of Holley Shelter, KwaZulu-Natal (South Africa) and Its Potential for Past Foragers

AbstractCurrent phyto-scapes (plant populations in their geo-spatial context) are not exact replicas of past foraging potential, yet they provide valuable data about the carrying capacity or potential of a foraging-scape. Knowledge about contemporary micro-ecologies and ethno-historical plant use can inform on behavioral aspects, should such plants be found in archaeological deposits. It is in this context that we explore existing information (data and literature) to establish the current vegetation types and micro-ecologies around Holley Shelter, KwaZulu-Natal, South Africa, that contains Middle and Later Stone Age occupations. We present the first plant species inventory consisting of &gt; 1500 taxa growing approximately a day’s foraging distance from the site, compiled from records provided by the South African National Biodiversity Institute and other sources. From this list, we generated separate checklists for foodplants (n = 450) and plants that have other uses (n = 337), to gain insight into the site’s current phyto-fitness potential. The resulting database is intended as a modern proxy for future work on the site’s archaeo-botany and palaeo-climatic reconstructions. The data is also applicable to other sites on the Savanna/Grassland Biomes of southern Africa with records of the same species. Here we use the foodplant checklist and what is known about the edible plant parts, their seasonality and the distribution of some species to speculate about land-use patterns. These hypotheses can be tested for the past with future archaeo-botanical work. We demonstrate that, compared to archaeological sites in the Eastern and Western Cape for which comparable data exist, Holley Shelter is rich in foodplants, and especially so in plant foods that are known to buffer against famine during the periodical droughts of inland South Africa.

Conservation biology of three threatened Limonium species endemic to Zakynthos Island (Ionian Islands, Greece)

Abstract Knowledge of the life history traits, reproductive biology and demography of rare species is fundamental for their conservation, yet plant population monitoring is uncommon. The restricted ranges of the Limonium species endemic to the Mediterranean area, combined with the vulnerability of their specialized littoral habitats, indicate the need for appropriate conservation measures. We evaluate the conservation status and estimate the future extinction risk of three Limonium species endemic to Zakynthos Island in the Ionian Islands, Greece (Limonium korakonisicum, Limonium phitosianum and Limonium zacynthium) using 5 years of monitoring data. We compile information on their geographical distribution, population dynamics, reproductive biology and genetic diversity. Population sizes and survival rates of seedlings exhibited marked annual fluctuations, although fecundity and relative reproductive success remained high throughout the monitoring period. We observed a dominance of mature individuals in all three species, indicating their increased tolerance to salinity. Three subpopulations each of L. phitosianum and L. zacynthium were genotyped using five microsatellite loci. The observed number of alleles and the low gene flow value potentially indicate reduced genetic diversity, inbreeding, and limited gene flow within and among subpopulations of both species. Based on the IUCN categories and criteria, we assess L. korakonisicum as Critically Endangered, L. phitosianum as Near Threatened and L. zacynthium as Endangered. Population viability analyses predict that, among the three species, L. zacynthium will face the highest risk of extinction within the next 50 years. Knowledge of the biology of these species provides data essential for identifying critical factors for their survival and for proposing targeted conservation measures.

Intraspecific trait variability in wild plant populations predicts neither variability nor performance in a common garden

Dryland restoration requires plant materials capable of performing well despite difficult growing conditions. Selecting plant materials with higher intraspecific trait variability (ITV) may support successful outcomes by enhancing the performance of those materials in restoration settings. However, maintaining ITV from wild populations is not well understood and requires further investigation if ITV is to be incorporated into native plant materials, which are often developed from wild‐collected seed grown in agricultural settings. We used two perennial plant species to explore whether (1) ITV measured at field sites predicts ITV in a common garden, (2) rankings of ITV among populations remain stable over time, and (3) higher levels of ITV promote survival and reproductive effort in a common garden. We measured ITV in specific leaf area and height for Bouteloua curtipendula and Heterotheca villosa at field sites and over 2 years in a common garden, as well as survival and flower production in the common garden. We also calculated climate distance between field sites, where seeds were originally sourced, and the common garden to account for the impact of climatic differences on ITV. We found that (1) ITV measured at field sites did not predict ITV in the common garden, (2) rankings of ITV across populations were inconsistent, and (3) relationships between ITV and performance were rare and differed by species. Our findings indicate that the utility of ITV in wild populations as a predictive tool may be limited.

Optimized guidelines for feminized seed production in high-THC Cannabis cultivars.

With the partial legalization of high-THC Cannabis sativa across 23 states for recreational use and 38 states for medical purposes in the United States, the Cannabis industry is poised for significant growth. Projected to reach a sales volume of $50.7 billion by 2028, this growth is driven by the trend of lifting Cannabis prohibition. High-THC C. sativa cultivars, containing more than 0.3% delta-9 tetrahydrocannabinol (Δ9-THC) as defined by the 2018 US Farm Bill, are used for both medicinal and recreational purposes. Cannabis sativa is a short day, dioecious, annual plant, where female plants are favored for THC production, which requires seed feminization techniques to ensure an accurate female plant population. This involves using an ethylene inhibitor to induce sex reversal, leading to male flower development on female plants, allowing for self-pollination and the production of feminized seeds. However, challenges such as seed viability and the occurrence of male flowers in progeny have been noted. This review provides guidelines to enhance the production of viable feminized seeds in high-THC Cannabis cultivars. Literature findings indicate that Silver Thiosulfate (STS) is the most effective ethylene inhibitor for sex reversal and seed feminization in high-THC Cannabis cultivars. Specifically, a single dose of 3 mM STS should be applied during the vegetative stage via foliar spraying until runoff, followed by exposure to a short photoperiod of up to 12 hours to induce flowering and seed production. Progeny plants should be assessed for seed germination rate and compared for growth performance with the original parent plant to assess the declining effects of inbreeding. Adhering to these guidelines can improve the quality and viability of feminized seeds, meeting commercial market standards and industry demands for high-THC Cannabis cultivars.

Evaluating the performance of traditional paddy (Oryza sativa L.) landraces under floating cultivation techniques in southern Tamil Nadu

Floating rice cultivation, a novel method, is essential for boosting crop yields and resilience amid climate change using flood-prone and water-saturated environments. This approach leverages aquatic resources such as lakes and reservoirs, enhancing agricultural productivity and ecosystem health. This study was conducted in 2023 at the Department of Agronomy, Agricultural College and Research Institute, Madurai to assess the suitability and production potential of cultivating traditional paddy varieties viz., Chinnar and Chithiraikar under floating conditions. Various substrates including soil, coir pith, wooden chips, sugarcane trash, thermocol, leaf compost, and jute bags were levelled out over paddy seeding trays (60 × 30 cm) and placed over bamboo rafts (120 × 120 cm) which served as the float base. Various parameters viz., germination (%), leaf area index (LAI), vigour index, plant population, dry matter production (g/m2), grain yield (kg/ha) and straw yield (kg/ha) were analysed. Results revealed that better crop establishment and crop growth were highly influenced by nursery and conditions with coconut coir outperforming other substrates. However, findings indicated that thermocol substrate is more productive in realizing higher yield attributes and yield (9.83 g/plant, 9.90 g/plant, respectively) of both Chinnar and Chithiraikar landraces of rice. Thus, floating rice cultivation offers a sustainable way to enhance productivity and adaptability, with traditional paddy varieties suitable for soilless media, though further research is needed to optimize its effectiveness.

Managing earliness and yield of cotton by modulating plant population, foliar boron feeding and mepiquat chloride application

ABSTRACT Early maturity and simultaneous increase in yield of cotton are pivotal for increasing the productivity of cropping systems involving cotton. Current two-year study was performed to simultaneously enhance the earliness and yield of cotton by modulating plant population (PP) (5.3 and 8.8 plants m−2), foliar boron (B) (0, 0.6 and 1.2 g/L B) and 0.07 g/L mepiquat chloride (MC) solution (at squaring and flowering stages) application. Internodes length was exalted at high PP (8.8 plants m-2) and B (1.2 g/L B), while declined by MC. Nevertheless, nodes above the white flower and cracked boll were decreased at high PP, and the application of B and MC indicated earlier cutout. Similarly, high PP, and application of 1.2 g/L B and MC at squaring reduced calendar and thermal time needed for flowering and boll opening. The boll maturation period was not affected by the application of B and MC but declined at high PP. Earliness index, production rate index (PRI) and seed cotton yield were increased at high PP, application of 1.2 g/L B and MC at squaring. In crux, increasing PP and B concentration, and MC application at squaring resulted in early maturity and enhanced seed cotton yield by modulating plant structure and time required for various phenophases.

Influence of terrain slopes on the longitudinal distribution of soybean seeds of two different seeders

Soybean is a widespread crop in world agriculture and is also of great importance for Brazilian agriculture and economy. Sowing with the correct longitudinal distribution of seeds plays an important role in the optimum development of the crop. A sowing can be influenced by dosing mechanisms, conductor tubes, soil covering, and different terrain slopes. Thus, this article presents the performance of two seeders (Semeato® Multiple SSM 27 ROTO and John Deere® 1111A), submitted to terrain slopes of +23%, 0%, and -23%, regarding seed distribution in the population and the percentage of acceptable, faulty, and multiple spacing. The in loco experimental data presented is scarce in the literature and may be useful for application in other lands. While for Semeato® Multiple SSM 27 ROTO, 0% and +23 slopes presented higher multiple spacing averages, for John Deere® 1111A, the slopes did not influence the multiple spacing occurrence. Nonetheless, in the studied area, the Semeato® Multiple SSM 27 ROTO presented results for the plant population closer to the desired reality.

Insects decline with host plants but coextinctions may be limited

The loss of wild plant populations is often assumed to lead to coextinctions, particularly among specialized insects. Despite global declines in both terrestrial insects and plants, the relationship between these trends remains elusive. Here, we address this gap by analyzing the relationship between population trends of insects and their host plants in Germany, encompassing over 150,000 interactions among 3,429 plant and 2,239 insect species, including both pollinators (bees and hoverflies) and herbivores (butterflies, moths, and sawflies). Our findings reveal parallel population declines of insects and host plants across taxa, except for more generalist hoverflies. However, simulated extinctions of threatened host plants led to limited coextinctions in insects. Notably, 96% of insect species retained over 25% of their host plant diversity, and among those, 98% still retained at least one common species in their interaction portfolio. Even highly specialized insects may persist because they tend to specialize in nonthreatened plant species. While uncertainties remain regarding the interchangeability of host plants, our findings suggest that insect coextinctions are far from a 1:1 match with plant extinctions. Our findings suggest the declining abundance of many plant species can contribute to insect decline yet challenge the common assumption that the extinction of threatened plant species will necessarily trigger an imminent extinction wave of associated insects. Interaction networks seem to be more resilient.