Planting Date and Different N-Fertilization Rates Differently Modulate Agronomic and Economic Traits of a Sicilian Onion Landrace and of a Commercial Variety

The onion is one of the most widespread bulb vegetables worldwide. Onion cultivation is common in Sicily, as is the use of local genotypes. Cultivation practices are of particular interest in optimizing yield, quality, and profits. The aim of this study was to assess the agronomic response of a Sicilian landrace (Bianca Calda di Comiso, coded L1) and a commercial variety (Bianca di Maggio, coded V1) to different planting dates and N fertilization rates. An economic appraisal was also performed. The two genotypes were assessed using an experimental split-split-plot design with four levels of nitrogen rates (0, 80, 160, and 220 kg N ha−1) and two different planting dates (8 October 2005 to 9 October 2006 for the early planting date, and 27 December 2005 to 30 December 2006 for the traditional planting date). The marketable yield and production parameters were significantly influenced by the nitrogen dose: higher doses led to a higher total yield, with yield peaks above 60 t ha−1 and the marketable yield ranging from 23% to 54%. Simultaneously, decreases in the firmness (from 7% to 19%) and scale content (from 1% to 3%) were also reported. The L1 landrace showed a higher production than the V1 variety. The crop year did not significantly affect the results, and the traditional planting date appeared to be the most suitable choice in obtaining the best agronomic response. Economic analysis showed that the L1 landrace, with high-N application treatments, produced greater net benefits and marginal rates of return. Thus, the L1 landrace exposed to the highest dosages of nitrogen (160 or 220 kg ha−1) and transplanted during the traditional planting period is the best choice from agronomic and economic points of view

Somatic embryogenesis through in vitro anther culture of Citrus sinensis L. Osbeck ‘Moro’

In many crops, anther culture is the most used method to induce gametic embryogenesis, aimed to regenerate homozygous plants. However, also somatic embryogenesis can be obtained by this method, when somatic tissue is involved in regeneration process. Many factors can affect this procedure, such as genotype, pre-treatments applied to floral buds, pollen developmental stage, donor plant states, culture media composition and growth culture conditions. Anthers of Citrus sinensis L. Osbeck, cv. Moro, were collected at the vacuolate stage, and after a chilling (4°C) pre-treatment of 7 days, were placed on the same medium, evaluating different temperature stresses applied after the placing in culture. In this study, the effect of three thermal treatments, compared with direct in vitro culture of the anthers (after the pre-treatment to the floral buds at 4 °C for 7 days), was observed in a Citrus genotype. Regeneration of embryos has been obtained and their characterization, through ploidy analysis and molecular analysis, showed that they were heterozygous tetraploids

Encapsulation of in vitro-derived propagules of two genotypes of Capparis spinosa (L.) from Pantelleria Island

Encapsulation technology, combining the advantages of zygotic or gamic seed with those of micropropagation, has recently attracted the interest of researchers as a new propagation approach, mainly due to the unsatisfying results of the traditional propagation strategies. The encapsulation of uninodal microcuttings (3-4 mm long) from two Sicilian Capparis spinosa (L.) genotypes (from Pantelleria Island: Tracino and Scauri) was evaluated, observing the influence of the calcium alginate coating and of three different growth regulators (PGRs): 6-Benzylaminopurine (BAP), Meta-Topolin (MT) and Zeatin (ZEA), on viability, regrowth and conversion of the propagules. Caper microcuttings were dissected and placed in different Murashige and Skoog-based artificial endosperms, enriched of MT or ZEA or BAP. The synthetic seeds obtained were sown on a medium with full strength salts concentration, enriched with 0,4 mg/L of naphtalene acetic acid and 0,7 mg/L of gibelleric acid. After 60 days, the following parameters were detected: viability, regrowth, number and length of the shoots and roots, conversion. The results confirm that encapsulation did not negatively affect the viability, which showed the highest percentage with BAP (100%) in Tracino and with ZEA (100%) in Scauri. Similar results were obtained in regrowth, with statistically significant differences among the three PGRs tested: Tracino showed the best regrowth on capsuled enriched with BAP (100%), Scauri with ZEA (100%). In addition, the synseed conversion was greatly affected by the PGR, and it was higher in artificial endosperm added with BAP in Tracino (56.6%) and ZEA in Scauri (23.3%) genotype

Establishment of a commercial organic hopyard in a Mediterranean environment: Production attributes and their relationship with soil texture

The cultivated hops are recently moving towards new growing areas in Southern Europe, boosted by the increasing number of craft breweries and by the higher vulnerability to climate change observed, for this crop, in the traditional growing regions. Despite this clear market and geographic trend, there is a lack of knowledge about pedoclimatic needs and agronomic performances of hops grown in the Mediterranean environment. Particularly, the agronomic potential of a new hopyard during its establishment period is poorly studied even in traditional growing zones. Moreover, a restricted number of plants were usually sampled to gather the few data available, thus leading to a probable overestimation of yield performance. A commercial organic hopyard in central Italy was established and a 2-year (2018-2019) field experiment was set-up to accurately investigate the cone and shoot yield potential of cultivar 'Cascade' and to understand how such yields are related to each other and to soil texture. Hop plants were two-years old when the experiment started; plant population was 4,000 plants ha -1. Forty points within the hopyard were sampled for soil analysis and yield traits. Data were analyzed accounting for spatial dependence of the sampling points. Results show a negative relation between clay content in the soil and hop yields, even though it was significant only in the exceptional rainy season of 2018. Shoot and cone yield were positively and strongly related, suggesting the green shoot yield in spring as a good predictor of hop production. Both shoot and cone yield significantly increased from the second to the third year (+11% and +16%, respectively); however, the unseasonably high rainfall of 2018 probably lowered the yield of the first experimental year. Cone yield attained over this 2-year study (1.24 t ha- 1 and 1.44 t ha- 1 for 2018 and 2019, respectively) was within the published ranges for mature plants. Similarly to cone production, shoot dry matter yield was lower in 2018 (197 kg ha-1) than in 2019 (218 kg ha-1). This study provides the first reliable in-formation on both cone and shoot yield potential of a young organic hopyard under Mediterranean climatic conditions

Iodine Biofortification and Seaweed Extract-Based Biostimulant Supply Interactively Drive the Yield, Quality, and Functional Traits in Strawberry Fruits

The horticultural sector is seeking innovative and sustainable agronomic practices which could lead to enhanced yield and product quality. Currently, plant biofortification is recognized as a valuable technique to improve microelement concentrations in plant tissues. Among trace elements, iodine (I) is an essential microelement for human nutrition. Concomitantly, the application of biostimulants may improve overall plant production and quality traits. With the above background in mind, an experiment was designed with the aim of assessing the interactive impact of a seaweed extract-based biostimulant (SwE) (0 mL L−1 (served as control) or 3 mL L−1 (optimal dosage)) and 0, 100, 300, or 600 mg L−1 I on the growth parameters, yield, fruit quality, minerals, and functional characteristics of the tunnel-grown “Savana” strawberry. SwE foliar application improved the plant growth-related traits, total and marketable yield, fruit color parameters, soluble solids content, nitrogen (N), potassium (K), and magnesium (Mg) fruit concentrations. Furthermore, an enhancement in the fruit dry matter content, ascorbic acid, and I concentration in fruits was detected when the SwE supply interacted with a mild I dose (100 or 300 mg L−1). The research underlined that combining SwE application and I biofortification increased the strawberry yield and quality and enhanced the plant nutritional status variation, thereby, determining a boosted strawberry I tolerance

Grafting Eggplant Onto Underutilized Solanum Species and Biostimulatory Action of Azospirillum brasilense Modulate Growth, Yield, NUE and Nutritional and Functional Traits

The grafting of vegetable crops is considered a valuable mean for ensuring the yield and quality under different cultivation conditions. Simultaneously, there are increasing research efforts in exploiting underutilised plants as potential rootstocks for vegetables to increase the sustainability of horticultural systems. In accordance with the European Green Deal, the application of biostimulants is a fashionable and ecological agronomic practice to enhance the production and quality of vegetables. Thus, the current research appraised the synergistic effect of grafting eggplant onto various allied potential rootstocks (Solanum torvum, S. aethiopicum and S. macrocarpon) and of applying a plant growth-promoting bacteria (Azospirillum brasilense DSM 2298) on eggplant growth, production, fruit quality traits (nutritional and functional features) and nitrogen use efficiency (NUE). The findings showed that ‘Gloria’ F1 plants grafted onto S. torvum or S. aethiopicum had a significant increase in plant height 50 DAT by 11.6% and 9%, respectively, compared with not grafted plants. Simultaneously, plants inoculated with A. brasilense DSM 2298 acquired a significant upsurge of plant height 50 DAT by 6% compared with the control. Our results revealed that S. torvum and S. aethiopicum-grafted plants improved their marketable yield by 31.4% and 20%, respectively, compared with not grafted ones. Furthermore, A. brasilense DSM 2298 significantly boosted the yield compared with the control plants. Plant type had no effect on fruit dry matter and firmness, whereas plants grafted onto S. macrocarpon showed a significant increase in the soluble solids content (SSC) and fruit K concentration compared with not grafted plants. Plants grafted onto S. torvum rootstock and inoculated with A. brasilense DSM 2298 had a significant increase in fruit protein concentrations compared with the combination not grafted × control. Moreover, S. torvum-grafted plants and those inoculated with the microbial biostimulant revealed the highest NUE values. The results evidenced that S. torvum and S. macrocarpon-grafted plants, inoculated with A. brasilense DSM 2298, had the highest ascorbic acid (average 7.33 and 7.32 mg 100 g−1 fw, respectively). Interestingly, S. torvum rootstock increased the chlorogenic acid concentration and reduced the glycoalkaloids concentration compared with not grafted plants. Our data also showed that A. brasilense DSM 2298 significantly increased SSC by 4.5%, NUE by 5.5%, chlorogenic acid concentration by 2.0% and the total anthocyanins by 0.2% compared to the control. Thus, our study underlined that S. aethiopicum rootstocks inoculated with A. brasilense DSM 2298 could represent a valid substitute to the common S. torvum rootstock

Combined effects of biostimulants, N level and drought stress on yield, quality and physiology of greenhouse-grown basil

Precise nitrogen (N) supply is an agronomic practice of crucial importance to achieve optimal crop performance without compromising product quality. However, excessive use of synthetic N fertilizers may have deleterious effects on both agroecosystem and human health. Thus, the development and use of strategies aiming to ameliorate the losses caused by water constraints and N deficiency are essential for fostering resilient and sustainable agroecosystems. In this regard, the impact of three drought stress levels (DS) [100%, 80% and 60% of the field capacity (FC)] in combination with four N supply rates (0, 50, 100 and 150 kg ha−1) on sweet basil cultivated in a protected environment was investigated. The interactive biostimulatory action of Kelpstar® seaweed extract (SWE) and Tyson® protein hydrolysate (PH) was also explored. The study focused on the effects of these treatments on yield, physiological attributes, functional traits, and volatile compounds profile. Drought stress led to a reduction in yield by 12.5% and 21.1% under irrigation at 80% and 60% FC, respectively, compared to well-watered plots (100% FC). Furthermore, drought stress levels linearly decreased total leaf area (-15.4% and -26.2% for DS80 and DS60, respectively), stomatal conductance (-14.2% and 34.1% for DS80 and DS60, respectively), nitrogen use efficiency (NUE) (4.0% and 10.0% for DS80 and DS60, respectively), and volatile compounds, such as trans-2-hexanal, 1-octen-3-ol and α-bergamotene. Conversely, an increase in N application rate positively influenced yield (8.6% and 12.2% for N100 and N150, respectively), total leaf area (22.2% and 16.5% for N100 and N150, respectively), specific leaf area (SLA), total chlorophyll (7.7% for N150), nitrate content, and the presence of specific volatile compounds, such as 1-octen-3-ol and α-bergamotene, when compared to no N application. Seaweed extract application caused an upsurge in yield (+17.5%), stomatal conductance (+25.8%), WP (+13.5%), total chlorophyll (+2.3%), nitrate (+3.4%), phenolics (+14.2), ascorbic acid (+28.2), as well as, 1-octen-3-ol, β-cis-ocimene, linalool and eugenol, compared to the control. Similarly, plant protein hydrolysate increased yield (+16.1), stomatal conductance (+10.4), WP (+13.7), total chlorophyll (+4.3), phenolics (+10.7%), ascorbic acid (+9.7%), β-cis-ocimene and eugenol, compared to the control. Notably, the increased yield, improved quality, and enchanced physiological traits observed after biostimulant application, especially under drought stress or N deficiency conditions, underscore the potential role of biostimulants in increasing resilience of basil plants. Thus, the foliar application of SWE and PH offer a valuable strategy for enhancing plant yield and quality under sub-optimal conditions, while simultaneously enhancing water and N use efficiency