Ioannis S. Tokatlidis

Lentil (Lens culinaris Medik.) production faces challenges due to shifting environmental conditions, potentially leading to a transition towards cooler or highland Mediterranean environments. This study assessed the responses of five lentil genotypes across five diverse locations (L1–L5) managed under organic cropping systems over two seasons, focusing on key parameters including seed yield (SY), crude protein (CP), cooking time (CT), seed loss percentage (SL), and yield loss per hectare (YL) caused by bruchid (Bruchus sp.). Excessive seasonal rainfall (500 mm), low winter temperatures (−17.9 °C), bruchid SL, and spring sowing were identified as crucial, particularly in challenging environments like highlands. Genotype selection was highlighted as essential for balancing yield and stability, with the small-seeded cultivar ‘Dimitra’ demonstrating lower YL due to bruchid. Additionally, increased CP was noted in response to heightened bruchid infestations. Specific recommendations were proposed for different environments: In productive lowland areas with low bruchid pressure and high CTs (L1), prioritizing cultivars like ‘Samos’, ‘Dimitra’, and ‘Thessalia’ enhances quality. Locations with high bruchid populations (L4) were not favored organic production but can serve as genetic resistance screening sites. High-elevation environments (L3, L5) proved significantly less productive, underscoring the requirement for earlier and winter-hardy cultivars. These insights guide lentil cultivation, emphasizing the need for tailored breeding strategies adaptable to changing environments.

The Honeycomb Selection Design (HSD) is an innovative experimental method whose main feature is the even and systematic entry arrangement. Its systematicity, if combined with the absence of inter-plant competition that maximizes the phenotypic expression and differentiation of individual plants, enables the implementation of single-plant selection as early as the initial generations of genetic segregation, facilitating plant breeders to identify superior genotypes. Due to the specificity of entry allocation and the complexity of statistical data analysis, a specialized software becomes necessary. This article provides a detailed presentation of the ‘rhoneycomb’, a free and open-source R package concerning the construction, visualization, and analysis of HSDs.

The coefficient of variation (CV) of yield may functionally be related to the mean. The expected exponential CV decline with increasing mean, i.e., the Taylor’s power law (TPL), is not always valid. Removal of this scale dependency allows for a scale-independent assessment of stability. The objective of this study was to interpret the validity of the homeostasis index (HI), i.e., the inverse CV value, suggested in breeding under nil competition as a selection criterion for progeny lines that oppose the acquired interplant variation. Data concerning the single-plant yield of various crops under a nil-competition regime were studies against the theoretical background of the above hypothesis. Simple correlations between logarithms of variances and respective means were used to assess the reliability of CV as a stability statistic in breeding trials under nil competition. A total of 8 of the 24 case analyses revealed a systematic variance dependence on the mean. The impact was more prevalent in experiments with extensive spatial heterogeneity and high CV scores. Conversion of variance to remove systematic dependence did not validate the CV~mean negative relationship. Because of variance dependence, caution is needed when interpreting the HI as a stability index. Misuse of the HI may entail the risk of bias, upgrading or downgrading a progeny line in its ability to withstand acquired dissimilarity between plants. Testing the validity of the variance seems necessary, and the calculation of HI on a converted variance may enhance the accuracy of identifying the most promising progeny lines.

Lentil is an important legume crop for human and animal dietary needs due to its high nutritional value. The effect of genotype and growing environment was studied on seed yield (SY), crude protein (CP) and mineral nutrients (macro and micronutrients) of five lentil genotypes grown at four diverse locations for two consecutive years under organic and conventional farming. The location within each year was considered as a separate environment (E). Data were subjected to over environment two-way analysis of variance, while a genotype (G) plus genotype × environment (GGE) biplot analysis was performed. Our results indicated the E as the main source of variation (62.3–99.8%) for SY, CP and macronutrients for both farming systems, while for micronutrients it was either the E or the G × E interaction. Different environments were identified as ideal for the parameters studied: E6 (Larissa/Central Greece/2020) produced the higher CP values (organic: 32.0%, conventional: 27.5%) and showed the highest discriminating ability that was attributed to the lowest precipitation during the crucial period of pod filling. E7 (Thessaloniki/Central Macedonia/2020) and E8 (Orestiada/Thrace/2020) had fertile soils and ample soil moisture and were the most discriminating for high micronutrient content under both farming systems. Location Orestiada showed the highest SY for both organic (1.87–2.28 t ha⁻¹) and conventional farming (1.56–2.89 t ha⁻¹) regardless the year of cultivation and is proposed as an ideal location for lentil cultivation or for breeding for high SY. Genotypes explained a low percentage of the total variability; however, two promising genotypes were identified. Cultivar “Samos” demonstrated a wide adaptation capacity exhibiting stable and high SY under both organic and conventional farming, while the red lentil population “03-24L” showed very high level of seed CP, Fe and Mn contents regardless E or farming system. This genetic material could be further exploited as parental material aiming to develop lentil varieties that could be utilized as “functional” food or consist of a significant feed ingredient.

Following their entrance into natural water reservoirs, the use of pesticides may adversely affect human health and the environment. Biobeds facilitate decontamination of agricultural wastewaters. Bioaugmentation could enhance biodegradation of pesticides and addition of an adsorbent, such as natural zeolite, may increase biobed efficacy. In this study, the bioaugmentation utility of Pseudomonas putida (biomixture A) and the impact of zeolites supplement (biomixture C) in biomixtures contaminated with the fungicides fluopyram (20 mg/kg), myclobutanil (10 mg/kg), and triticonazole (30 mg/kg) were examined. A biomixture devoid of zeolites and inoculant was used as control (biomixture B). Bioaugmentation enhanced the dissipation rate of all fungicides (DT₅₀ values of 9.5, 7.7, and 10.5 days for myclobutanil, fluopyram, and triticonazole, respectively), contrary to zeolite-treated samples in which the dissipation was prolonged. According to α-diveristy results, bioaugmentation treatment displayed higher microbial diversity than control samples, while the highest diversity was recorded in the case of natural zeolites. The results of β-diversity showed that bioaugmentation and natural zeolites affected microbial diversity during the first days of the experiment via the support of gammaproteobacteria (Proteobacteria) growth.

Natural selection favors the competitive ideotype, enabling native plants to survive in the face of intense competition. The productive ideotype is the goal of artificial selection to achieve high crop yields via the efficient use of resources in a self-competition regime. When breeding is established under inter-genotypic competition, the competitive ideotype dominates and may fictitiously become selectable. The productive ideotype becomes selectable at the nil-competition regime, where widely spaced individuals prevent plant-to-plant interference for any input. Principal reasons bring to the fore the productive ideotype that combines low competitiveness and improved plant yield efficiency. Crop spacing via the productive ideotype is mandated to alleviate the varying optimum density and ensure efficient use of resources inter-seasonally, cope with intra-field variation and optimize resource use, compensate for missing plants and promote stability, counteract unpredictable stresses and offer a buffer against environmental diversity, and adopt low-input agriculture to conserve natural resources and the environment. For breeding toward the productive ideotype, nil-competition is the due condition to overcome the confounding effects of competition, maximize phenotypic differentiation and facilitate selection from an early segregating generation, optimize heritability due to moderated environmental variance and experimental designs that sample spatial heterogeneity, apply high selection pressure focusing exclusively on the targeted genotype, and avoid the risk of bias selection or loss of desired genotypes due to proximity to empty hills. The view of a modern crop variety composed of genotype(s) belonging to the productive ideotype is a viable option to reach crop resilience serving sustainability in enormously fluctuating agroecosystems.

Editorial: Crop response to density: Optimization of resource use to promote sustainability

Genetic differentiation between 40 lentil genotypes was tested using molecular markers. The genotypes were produced from a Greek landrace of commercial interest via the honeycomb breeding methodology, i.e., single-plant selection in the absence of competition, across three successive pedigree generations. The selected genotypes from each generation were examined for genetic relationships using 15 SSR molecular markers with HRM analysis. As expected, low variation among consecutive generations at the level of 2.5–7.7% was detected. Analysis of molecular variance (AMOVA) revealed that partitioning of this variation was at higher percentage within each generation’s population than between them. Population structure analysis indicated that ongoing selection could effectively shift the allelic composition in each generation. The applied honeycomb breeding methodology that effectively improved progeny yield and seed quality increased the percentage of favorable alleles altering allelic composition but not eliminating genetic variation of the breeding population.

The performance of Vicia sativa L. cultivars and cultivar mixtures used as green manure under two seed rates in a Mediterranean environment was investigated in a split plot design, over the period 2014–2016. Six common vetch cultivars grown in pure stands or in mixtures were established at two seed rates (S₁ = 100 Kg ha⁻¹ and S₂ = 180 kg ha⁻¹). Growth traits (e.g., plant height, biomass yield, LAI, CGR) were monitored until incorporation into topsoil. The nitrogen (N) concentration of the incorporated biomass along with the decomposition rate were determined, and the effects on the N supply to the soil were evaluated two, four and six months after biomass incorporation. The increment in residual soil Ν four months after green manuring fluctuated from 17 to 45 kg ha⁻¹ among cultivars, and after six months, from 22 to 50 kg ha⁻¹. The average decomposition rate of organic substances was slightly higher for S₂ for all time intervals; however the highest value (62.6%) was recorded for S₁ six months after biomass incorporation. Seed rate-independent genotypes were identified with regard to the decomposition of organic matter and are suggested as being suitable for green-manuring farming systems with a low seed rate, a fact that offers options with economic and environmental benefits.