Plant Density Research Articles

Asymmetric effects of planting pattern and density on leaf-height traits of Glycine max and Amaranthus retroflexus

Abstract Environmentally sustainable weed management is crucial to meet the increasing demand for food. Previous studies have demonstrated that improving spatial uniformity and planting density can effectively suppress weeds. However, research on how planting patterns (PPs) affect the functional traits of crops and weeds is limited. In 2019 and 2021, we conducted a field experiment to compare the functional traits and biomass of Glycine max and Amaranthus retroflexus in two PPs—row (R) and equidistant (E)—with varying combinations of G. max and A. retroflexus densities. We found that the EPP amplified the competitive ability of G. max in size-asymmetric competition with A. retroflexus, and this advantage increased alongside higher G. max density, primarily due to functional traits related to light acquisition. In the EPP, G. max established a closed canopy during the early growth stage, reducing light availability to A. retroflexus. This advantage was reflected in higher leaf area index (LAI) and leaf dry weight (LDW) for G. max in the EPP than in the RPP, while A. retroflexus experienced reduced LAI and plant height (PH) due to increased shading in the EPP. Consequently, the EPP enhanced the total biomass and yield of G. max by an average of 40.81% and 37.72%, respectively, while the biomass of A. retroflexus decreased by an average of 34.52% compared to the RPP. These results suggest that adopting an EPP with a high density of G. max, could be an effective strategy for suppressing A. retroflexus and improving crop yield.

Influence of Low Concentration of Paclobutrazol and Its Application Close to the Main Trunk on Fruiting of Mango in Ultra High Density Plantations

Control of flowering and fruiting in mango is achieved by the application of Paclobutrazol (PBZ) in many commercial orchards. However, growers tend to use very high concentrations of the chemical, resulting in high costs of operation and long-term effects. This study examines the impact of low concentrations and varying application methods of PBZ on mango fruit yield in ultra-high-density plantations. Here 3 methods of application and 4 levels of PBZ concentrations (PBZ 23% SC) were tried in a 3 year study. Application of PBZ at N1 (close to the trunk, also termed as collar drench), N2 (20 cm away from the trunk) and N3, (1 m away from the trunk), all resulted in similar number of fruits and fruit weights. Using very low concentrations of PBZ, 4 (0.37 g a.i. /m canopy diameter (cd), 5 (0.46 g a.i. /m cd) and 6 (0.55 g a.i. /m cd) ml/2 liter water, it was found that the lowest 0.37 g a.i. /m cd is enough to get statistically higher fruit yield. These findings: a very low dose of PBZ can result in high productivity and a requirement of least volume of the solution when applied as a collar drench would make the use of PBZ more sustainable and encourage more growers to adopt the hormonal use for mango production.

Evaluating rice lipid content, yield, and quality in response to nitrogen application rate and planting density

To investigate the effects of nitrogen (N) application rate and planting density (D) on the contents of lipid and free fatty acid, fatty acid composition, yield and quality of rice grain, a field experiment was conducted using Koshihikari (japonica) as experimental material from 2021 to 2022 with three N levels (90, 150 and 210 kg ha-1, denoted as N1, N2 and N3, respectively) and three transplanting densities (19.0 × 104, 26.7 × 104 and 40.0 × 104 plants ha-1, denoted as D1, D2 and D3, respectively). The results showed that N application rate and planting density had highly significant impacts only on the contents of free fatty acid and saturated fatty acid, respectively. Increased N and planting density enhanced the contents of lipid (29.41 mg g-1) and free fatty acid (21.47%). The highest values were obtained under N3D3 increasing by 7.02% and 3.23 percentage points, respectively, compared to other treatments. No significant differences in lipid content were found among treatments, whereas free fatty acid exhibited significant differences. The unsaturated fatty acid content increased with increasing N but first decreased and then increased with increasing planting density, while saturated fatty acid content showed the opposite trend. Appropriate N level and planting density improved the relative chlorophyll content and net photosynthetic rate of rice flag leaves, as well as increased grain yield, effective panicle number and spikelete number per panicle, but decreased the seed setting rate. Under N2D2, the relative chlorophyll content and net photosynthetic rate remained relatively high throughout the grain filling stage, resulting in the highest grain yield, with increases of 43.87-47.03% compared to other treatments. A moderate N level improved the milling quality of rice, while increased planting density reduced it. However, both increased N and planting density reduced the appearance quality and cooking and eating quality of rice. Overall, the effects of increasing N application rate and planting density on enhancing rice lipid and free fatty acid contents were limited. A combination of 150 kg ha-1 N application rate and 26.7 × 104 plants ha-1 was recommended for achieving relatively higher yield, lipid content and better grain quality.

Dynamics of stand density and self-thinning in Chinese fir plantations: theoretical insights and empirical validation

IntroductionStand density management is essential for adaptive silviculture, thinning decisions, growth modeling, and yield prediction in forestry, particularly for plantations. Despite extensive research on self-thinning rules and the maximum size-density law, significant gaps remain in the biophysical understanding and validation of the relationships among key stand variables and parameters.MethodsThis study theoretically explored and validated the relationship between maximum size-density and two key metrics: average diameter at breast height (D) and tree height (H). We used time-series data from a 30-year clear-cut, fully stocked Chinese fir plantation, a fast-growing commercial species in China, for validation.ResultsA growth balance status for fully stocked stands was proposed, wherein prior to self-thinning, the growth rate of the stand basal area (G) aligns with that of the average tree height (H), expressed as G'/(G−b0)=H'/H and approaching a constant slope, b1. Generalized maximum size-density and stand density index (SDI) equations were developed: N1.0=A×D−2 and SDI=A⋅D−2 with A=4×(b0+b1H)/π, differing from traditional equations. Additionally, a generalized self-thinning equation, v=kHqN1.0−1 or w=c1HqN1.0−1, was introduced, indicating that in fully stocked stands, tree volume or biomass depends on both tree height and tree count.DiscussionThese findings advance understanding of the maximum size-density law and self-thinning boundary, providing refined tools for managing stand density in Chinese fir plantations.

A Multi Source Data-Based Method for Assessing Carbon Sequestration of Urban Parks from a Spatial–Temporal Perspective: A Case Study of Shanghai Century Park

As urbanization accelerates globally, urban areas have become major sources of greenhouse gas emissions. In this context, urban parks are crucial as significant components of carbon sinks. Using Shanghai Century Park as a case study, this study aims to develop an applicable and reliable workflow to accurately assess the carbon sequestration capacity of urban parks from a spatial–temporal perspective. Firstly, the random forest model is employed for biotope classification and mapping in the park based on multi-source data, including raw spectral bands, vegetation indices, and texture features. Subsequently, the Net Primary Productivity and biomass of different biotope types are calculated, enabling dynamic monitoring of the park’s carbon sequestration capacity from 2018 to 2023. Moreover, the study explores the main factors influencing changes in carbon sequestration capacity from the management perspective. The findings reveal: (1) The application of multi-source imagery data enhances the accuracy of biotope mapping, with winter imagery proving more precise in classification. (2) From 2018 to 2023, Century Park’s carbon sequestration capacity showed a fluctuating upward trend, with significant variations in the carbon sequestration abilities of different biotope types within the park. (3) Renovation and construction work related to biotope types significantly impacted the park’s carbon sequestration capacity. Finally, the study proposes optimization strategies focused on species selection and layout, planting density, and park management.

Creeping Stem 1 regulates directional auxin transport for lodging resistance in soybean.

Soybean, a staple crop on a global scale, frequently encounters challenges due to lodging under high planting densities, which results in significant yield losses. Despite extensive research, the fundamental genetic mechanisms governing lodging resistance in soybeans remain elusive. In this study, we identify and characterize the Creeping Stem 1 (CS1) gene, which plays a crucial role in conferring lodging resistance in soybeans. The CS1 gene encodes a HEAT-repeat protein that modulates hypocotyl gravitropism by regulating amyloplast sedimentation. Functional analysis reveals that the loss of CS1 activity disrupts polar auxin transport, vascular bundle development and the biosynthesis of cellulose and lignin, ultimately leading to premature lodging and aberrant root development. Conversely, increasing CS1 expression significantly enhances lodging resistance and improves yield under conditions of high planting density. Our findings shed light on the genetic mechanisms that underlie lodging resistance in soybeans and highlight the potential of CS1 as a valuable target for genetic engineering to improve crop lodging resistance and yield.

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.

MADS-box encoding gene Tunicate1 positively controls maize yield by increasing leaf number above the ear.

The leaves above the ear serve as a major source of carbohydrates for grain filling in maize. However, increasing the number of leaves above the ear to strengthen the source and improve maize yield remains challenging in modern maize breeding. Here, we clone the causative gene of the quantitative trait locus (QTL) associated with the number of leaves above the ear. The causative gene is the previously reported MADS-box domain-encoding gene Tunicate1 (Tu1), which is responsible for the phenotype of pod corn or Tunicate maize. We show that Tu1 can substantially increase the leaf number above the ear while maintaining the source‒sink balance. A distal upstream 5-base pair (bp) insertion of Tu1 originating from a popcorn landrace enhances its transcription, coregulates its plastochron activators and repressors, and increases the number of leaves above the ear. Field tests demonstrate that the 5-bp insertion of Tu1 can increase grain yields by 11.4% and 9.5% under regular and dense planting conditions, respectively. The discovery of this favorable Tu1 allele from landraces suggests that landraces represent a valuable resource for high-yield breeding of maize.

Microbial Basis for Suppression of Soil-Borne Disease in Crop Rotation

The effect of crop rotation on soil-borne diseases is a representative case of plant–soil feedback in the sense that plant disease resistance is influenced by soils with different cultivation histories. This study examined the microbial mechanisms inducing the differences in the clubroot (caused by Plasmodiophora brassicae pathogen) damage of Chinese cabbage (Brassica rapa subsp. pekinensis) after the cultivation of different preceding crops. It addresses two key questions in crop rotation: changes in the soil bacterial community induced by the cultivation of different plants and the microbial mechanisms responsible for the disease-suppressive capacity of Chinese cabbage. Twenty preceding crops from different plant families showed significant differences in the disease damage, pathogen density, and bacterial community composition of the host plant. Structural equation modelling revealed that the relative abundance of four key bacterial orders in Chinese cabbage roots can explain 85% and 70% of the total variation in pathogen density and disease damage, respectively. Notably, the relative dominance of Bacillales and Rhizobiales, which have a trade-off relationship, exhibited predominant effects on pathogen density and disease damage. The disease-suppressive soil legacy effects of preceding crops are reflected in compositional changes in key bacterial orders, which are intensified by the bacterial community network.

Development of high-speed precision maize metering device for dense planting pattern with standard ridges

This study proposed a high-speed precision dual-chamber maize metering device for the dense planting pattern with standard ridge promoted in China. Through theoretical analysis of the sowing process, parameters for the key components have been designed. The metering device is capable of planting two rows in a single pass for high-speed precision seeding. The effect of operating speed and negative pressure on seed metering quality was investigated. A high-speed camera was used to capture the trajectory of maize seed at different operating speeds, and it was found that intra-row shifts were caused by collisions at the mouth of the seed guide tube and rotation of the seed as it fell. Employing a two-factor, five-level orthogonal rotation test, Investigated the optimal operating parameters for the maize metering device. Response surface analysis showed that optimum seed metering quality was achieved at 14.2 km/h and 13.5 kPa. Validation tests showed a qualified rate of 97.93%, with a coefficient variation of 8.97% for this method. Additionally, an energy consumption analysis indicated a reduction in operating energy consumption of approximately 32% compared to conventional air suction seed metering devices for dense planting with large ridges on the same area of farmland. This study provides insights for reducing energy consumption in the seeding process, contributing to the sustainable development of agricultural resources.

Integrating Nitrogen, Water, and Other Management Practices to Improve Grain and Ratoon Forage Yields in Perennial Rice

Perennial rice has recently garnered global attention due to its potential to save on seeds and labor costs and its high production efficiency. The “mid-season rice–ratoon forage” mode is a new planting system that has emerged in recent years. However, detailed information is still lacking on the regenerative characteristics, grain and ratoon forage yields, and forage nutrient content of perennial rice under different planting densities, nitrogen (N) rates, stubble heights, and water management practices. Four experiments with perennial rice were conducted in Sichuan Province, Southwest China, from 2017 to 2022. The results show that the rice grain and ratoon forage yields were significantly affected by year, planting density, and N. The grain yield was 28.18% and 60.81% lower in 2018F and 2019F, respectively, than in 2017F; similarly, the ratoon forage yield was 29.01% and 52.74% lower in 2018S and 2019S, respectively, than in 2017S. The low grain yield was mainly associated with lower numbers of spikelets per panicle and panicles per m2, which resulted from a lower regrowth rate, and the low ratoon forage yield was mainly attributed to the lower regrowth rate. The rice grain and ratoon forage yields increased with an increase in the N rate and planting density. The ratoon forage was found to be rich in crude protein, crude fat, crude fiber, calcium, nitrogen, phosphorus, potassium, and other nutrients. Moreover, the content of these nutrients increased significantly with an increase in the N rate. The regrowth rate and maximum tillers showed trends of first increasing and then decreasing with an increase in the stubble height under dry and wet alternation irrigation during the winter season. When the relative soil moisture decreased to below 80% during the winter season, the regrowth rate and seedling development index could reach more than 99% and 84%, respectively. Our results suggest that integrating N, water, and other management practices (including the combination of a 150 kg ha−1 N rate, 18.0 hills per m2, 10–20 cm rice stubble height, and alternating dry and wet irrigation during the winter season) is a feasible approach for achieving high grain and ratoon forage yields in perennial rice systems.

Improvement of Transplanting Rice Yield and Nitrogen Use Efficiency by Increasing Planting Density in Northeast China Under the Optimal Nitrogen Split-Fertilizer Applications

There are few studies on how nitrogen (N) fertilizer application rates and transplanting densities impact rice yield, root distribution, and N use efficiency in the cold regions of Northeast China. This research involved a two-year field trial utilizing Jinongda 667 as the material. In 2021, three N split-fertilizer applications—T1 (6:3:1), T2 (5:3:2), T3 (4:3:3)—and two transplanting densities—D1 (30 cm × 13.3 cm) and D2 (30 cm × 20 cm)—were compared with the conventional cultivation mode (T0: 175 kg N hm−2, 6:3:1), whereby the N application mode most suitable for increasing density was explored. In 2022, four N application levels—0 (N0), 125 (N1), 150 (N2), and 175 (N3) kg N hm−2—were assessed under the same density treatment to analyze the yield, resource utilization efficiency, and root traits of Jinongda 667. The results indicated that when the transplanting density was 30 cm × 13.3 cm, the application of 5:3:2 fertilizer was more conducive to improving rice yield. Increasing planting density under reduced N input significantly enhanced both rice yield and N use efficiency. In contrast to the conventional cultivation method (D2N3), the treatment of increased planting density (D1N2) under reduced N input led to a 21.2% rise in the number of panicles per square meter and an 8.6% boost in rice yield. Furthermore, increasing planting density under reduced N input significantly enhanced the agronomic efficiency of N fertilizer, the apparent utilization rate, and the N harvest index. It also boosted the SPAD value, photosynthetic rate, and the utilization efficiency of light and N resources in rice. However, it was noted that root enzyme activity decreased. This study demonstrated that increasing planting density, combined with the N application mode of 5:3:2 and an N application rate of 150 kg hm−2, maximized resource utilization efficiency, optimized root absorption capacity, and resulted in higher yields.

Characterization of Key Phytoconstituents in Nigella Oil from Diverse Sources and Their Transfer Efficiency During Oil Processing

Nigella sativa L., which is commonly referred to as black cumin, is a globally recognized plant for the nutraceutical and pharmaceutical values of its seed oil. While numerous studies have investigated Nigella oil, there is a scarcity of information regarding the variation of key phytoconstituents in Nigella oil from diverse seed sources. It is also unclear whether the variation in phytoconstituents across different seed sources translates to variations in their respective oils, which is important for understanding their health benefits. Additionally, there is a gap in information on how specific phytochemicals transfer from seed to oil during the oil pressing. Therefore, this study investigated Nigella sourced from different genotypes and agricultural practices (planting densities and sowing times) to determine total phenolic content (TPC), antioxidant capacity (FRAP and CUPRAC), thymoquinone (TQ), and fatty acid composition. The results showed significant variation of TPC (87.4–144.1 mg gallic acid equivalents (GAE)/100 g), FRAP (454.1–560.9 mg Trolox equivalents (TE)/100 g), CUPRAC (356.3–482.5 mg TE/100 g), TQ (1493.5–2268.4 mg TQ/100 g), saturated fatty acid (SFA) (65.9–83.7 mg/g), monounsaturated fatty acid (MUFA) (42.5–67.8 mg/g), and polyunsaturated fatty acid (PUFA) (266.1–383.4 mg/g) in the oil derived from the seeds of different genotypes and agricultural practices. The total transfer of TPC, FRAP, and CUPRAC into the screw-pressed oil was relatively low, contributing only 2.3–3.7%, 7.1–11.7%, and 1.5–2.3%, respectively, of their total value in the respective seed. However, the transfer of TQ, SFA, MUFA, and PUFA was observed to be comparatively higher, contributing 32.8–48.5%, 60.8–84.2%, 45.6–74.4%, and 43.1–69.4%, respectively, of their total value in the respective seed. There was no strong correlation observed among TPC, FRAP, CUPRAC, and TQ, and none of the fatty acids showed a strong correlation with these variables.

Biennial Variation and Herbivory Affect Essential Oils of Ipomoea murucoides and Stomata Density of Neighbor Plants

Essential oils (EOs) are mixtures of volatile organic compounds that mediate plant interactions and are also appreciated for their biological properties in aromatic plants. However, the study of EOs in wild plants with biological activity has been neglected. Ipomoea murucoides is a wild species with allelopathic and insecticide activities; however, the climate factors associated with EOs and their role in intra- and interspecific interactions are still unknown. We investigated the effects of temperature, rain, and solar irradiance for two years on the EOs of I. murucoides and documented the effect of herbivory (without, <20%, >20%, and mechanical damage) on their composition. We evaluated the receptivity to possible infochemicals in conspecific and congeneric neighbors to I. murucoides plants exposed to methyl jasmonate (MeJA), herbivory by Ogdoecosta biannularis and without an elicitor. We measured the stomatal density and aperture in the second leaf generation of the neighbor plants. The year and herbivory >20% affected the composition of EOs. Nerolidol could be a biological marker for herbivory. We concluded that herbivory and rain irregularity contribute to EOs changing. The response in the stomatal density in plants not consumed by I. pauciflora but near I. murucoides under MeJA or herbivory gives evidence of interspecific plant–plant communication.

Respon Pertumbuhan dan Hasil Microgreens Beberapa Varietas Tanaman Caisim (Brassica juncea L.) pada Berbagai Jarak Tanam

The diminishing amount of land available for agriculture and the growing demand for nutritious food have made it necessary to find alternative sources of fresh vegetables. Urban farming, especially the cultivation of microgreens, can help meet this demand. Microgreens offer several advantages, such as time and cost savings, and they require minimal space while growing quickly. However, the optimal spacing for different types of microgreens is not extensively documented, as research on microgreens is still limited in Indonesia. The Brassicaceae family is one of the most commonly cultivated families for microgreens. This study was carried out at Room A, Faculty of Agriculture, Singaperbangsa Karawang University, Campus 2. The experimental method used was a factorial randomized block design (RBD Factorials) with two treatments for varieties and three for spacing, repeated five times, resulting in 30 experimental units. Factor I, Varieties, consisted of v1 (Tosakan) and v2 (Shinta). Factor II, Spacing, consisted of j1 (1 cm x 1 cm), j2 (1 cm x 2 cm), and j3 (2 cm x 2 cm). The data were analyzed using an analysis of variance (Uji F) at a 5% level. If the results of the analysis of variance were significantly different, the study continued with a multiple range test (DMRT) at a 5% level to determine the best-performing treatment. There was an interaction between the treatments for microgreen varieties and spacing on parameters such as plant density, dry weight of the plant, and fresh weight. There was a significant effect of the variety on the parameter of chlorophyll content, and a significant effect of spacing on the parameters of plant growth rate and the age of leaf appearance. Additional types of plants are needed to determine significant differences related to spacing and their interactions.

Isolation and characterization of non-rhizobial bacteria and arbuscular mycorrhizal fungi from legumes

This study investigates non-rhizobial endophytic bacteria in the root nodules of chickpea (Cicer arietinum L), faba bean (Vicia faba), and cowpea (Vigna unguiculata L. Walp), as well as arbuscular mycorrhizal fungi in the rhizospheric soil of chickpea and faba bean. Out of the 34 endophytic bacterial populations examined, 31 strains were identified as non-rhizobial based on nodulation tests. All strains were assessed for their plant growth-promoting (PGP) activities in vitro. The results revealed that most isolates exhibited multiple PGP activities, such as nitrogen fixation, indole-3-acetic acid (IAA) and ammonia (NH3) production, phosphate solubilization, and exopolysaccharide production. The most effective PGP bacteria were selected for 16S rRNA analysis. Additionally, a total of 36 species of native arbuscular mycorrhizal fungi (AMF) were identified. Acaulospora (100%) and Scutellospora (91.66%) were the most prevalent genera in Cicer arietinum L. and Vicia faba L. plants, respectively. Acaulospora also exhibited the highest spore density and relative abundance in both plants. Moreover, the root colonization of Cicer arietinum L. and Vicia faba L. plants by hyphae, vesicles, and arbuscules (HVA) was significant. The findings of this study provide valuable insights into non-rhizobial endophytic bacteria associated with legume root nodules and the diversity of AMF. These organisms have great potential for PGP and can be manipulated by co-inoculation with rhizobia to enhance their biofertilizer effectiveness. This manipulation is crucial for promoting sustainable agriculture, improving crop growth, and advancing biofertilizer technology.

Influence of CuO nanoparticles on photosystem II structural stability and functional activity of corn (Zea mays L.) under drought stress

Photoinhibition and photooxidation of photosystem II (PSII) is one of the key damages caused by drought stress. The present study aimed to assess whether or not foliar application of copper oxide nanoparticles (CuO NPs) is effective in promoting PSII stability and activity in corn plants under drought stress. Three-week old plants of corn were subjected to drought stress and varying levels of CuO nano-particles (0, 25, 50, and 100 mM) of the rooting medium. In this study, the effects of foliar application of copper oxide nanoparticles were assessed on growth, plant water status, nutrient uptake and structural stability of photosystem II of drought stressed corn plants. Drought stress impeded overall growth of the corn plants by reducing leaf relative water content, water potential, chlorophyll a content, and accumulation of K+ in plant leaves and roots. Exogenous application of 25 mM CuO NPs significantly enhanced the growth of corn. Exogenous application of CuO NPs improved the dry biomass and length of roots of the corn plants under drought stress. Although the application of nano-particles did not change leaf photosynthetic pigments, relative water content, K+ accumulation, it enhanced the accumulation of K+ in roots. Drought stress did not affect the structural stability of PSII, but it reduced its activity (performance index, PIABS) due to changes in the reaction center density and the biochemical reaction efficiency or electron transport capability. Exogenous application of CuO NPs improved PIABS due to increase in active reaction center density and electron transport efficiency. However, 100 mM CuO NPs application caused PSII damage at the donor end and reduced active reaction center density in the corn plants under both normal and drought stress conditions. The present findings provide a baseline information that foliar application of CuO-nanoparticles in low concentrations can improve the growth of corn by improving accumulation of K+ and increasing PSII activity. Further research is required to explore its effect on cellular redox balance and activities of PSII and PSI, and optimum dose of CuO-nanoparticles for developing formulations for their commercial applications in farmers’ fields.

Flower scent, pollinators, and effects of proximity between plants on fruit set of the rare, threatened, and endemic Daphne rodriguezii

AbstractThis study focuses on Daphne rodriguezii, a threatened plant species that is endemic to Menorca in the Balearic Islands of the Western Mediterranean. The main objective was to investigate the volatile organic compounds (VOCs) in the floral aroma, as well as the timing and chemical variations in scent production. The primary pollinators were identified, and the relationship between their behavior and the chemical profile of the floral scent was investigated. Furthermore, the impact of plant density on fruit set rates was evaluated to obtain valuable insights for conservation and habitat‐management initiatives. The findings reveal that D. rodriguezii emits a distinct sweet floral aroma that primarily consists of benzenoids and linalool derivatives. Scent emission occurs during the evening and night, coinciding with the activity period of moths (Autographa gamma), which were identified as the primary pollen vectors for this self‐incompatible species. The fruit set values exhibit a positive correlation with the proximity between plants. These results emphasize the importance of moths and plant proximity as crucial factors to consider in the conservation management of this species.

For California perennial crops facing climate change, water use stays stable while planting density increases

With climate change, there has been increasing concern over allocations of scarce water supplies in California during times of drought. This study looks at how practices in perennial crops have changed over time, specifically related to application of irrigation water and to planting densities. We use University of California Sample Costs of Production Budgets from 1980 to 2021 for all major perennial crops in California to compile information on the commonly implemented irrigation and planting practices across various crops and regions. After controlling for regional variation in water applied due to agroclimatic factors, irrigation water use per acre has remained largely stable for most crops, while planting densities have increased for many crops, including olives, grapes, avocados, plums, and almonds. A notable exception is pistachios in the South San Joaquin Valley, which experienced an increase in water applied, with stable yields and planting densities. Our methods of calculating significant trends in water use, including yields and density of orchards, give further insight into the use of water in California agriculture.

Evaluation of Growth and Yield of Vertically Trained Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] under Different Levels of Spacing, Training and Pruning under Rain Shelter

This study investigated the effects of spacing, training and pruning on the growth and yield of watermelon hybrid ‘Saraswati’ trained vertically under rain shelter. The treatments were factorial combinations of three planting densities (1.50 m × 0.60 m, 1.50 m × 0.45 m and 1.50 m × 0.30 m), two training levels (nipping to one vine, nipping to two vines) and two pruning heights (pruned at 2m and unpruned) arranged in randomized block design with two replications and control with horizontal training of vines in open condition. Spacing, training and pruning levels had varying influence on growth and yield parameters of vertically trained watermelon. Wider spacing of 1.5 m x 0.6 m recorded the highest vine length, highest fruit weight and yield per plant (6.82 kg). Earliness in days to flowering as well as node number was observed in widely spaced plants trained to single vine. Plants trained to two vines exhibited the highest number of fruits per plant, yield per plant and yield per plot. Unpruned plants trained to two vines at closer spacing of 1.50 m × 0.30 m recorded the highest number of fruits per plant and yield per plot (90.10 kg).