In the present study, we investigated the irrigation of L. angustifolia plants and drying temperatures on the yield of dry leaves and lavender essential oil. Plants were irrigated using an on-surface system with drip lines. Plants without additional irrigation were the control object. Each dose of water consisted of 15 mm. The total amount of water used for irrigation in 2016 and 2017 was 90 L·m⁻². The plant raw material was dried using two methods: in natural conditions and convectively. Natural drying was performed in a shaded room at a temperature of 20–22 °C for five days. The convective drying process was carried out in a drying oven in a stream of air at 35 °C, flowing parallel to the layer being dried at 0.5 m·s⁻¹. Under the influence of irrigation, there was an increase in the yield of fresh and airdried leaves and a higher content of essential oil (EO) than in the cultivation without irrigation. The EO obtained from irrigated plants was characterized by higher contents of caryophyllene oxide (9.08%), linalool (7.87%), and β-caryophyllene (4.58%). In nonirrigated crops, α-muurolol (19.67%), linalyl acetate (15.76%), borneol (13.90%), γ-cadinene (8.66%), camphor (2.55%) had a higher percentage in the EO. After drying under natural conditions, the airdried herb yield and leaf yield of lavender were higher by 25% and 17%, respectively, as compared to the raw material dried at 30 °C. Higher drying temperatures (30 °C) increased the EO by 18% on average and total phenolic acid (TPA) by 50%. The plant material dried at 30 °C, with a larger amount of TPA, showed higher antioxidant activity (AA) in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) tests. Linalyl acetate (15.76%) and linalool (7.87%) were predominant in the EO extracted from the oven-dried herb. Drying under natural conditions resulted in a decreased content of linalyl acetate (0.89%), β-caryophyllene (0.11%), linalool (1.17%), and camphor (1.80%) in comparison with thermal drying. Linalool, linalyl acetate, and β-caryophyllene had a higher percentage in the EO extracted from the raw material obtained from irrigated and oven-dried plants, whereas camphor was found to have a larger percentage in the case of the EO from nonirrigated plants. Our study reveals that there are prospects for the practical use of irrigation in lavender cultivation and of the raw material preservation method in order to modify the EO content and chemical composition.

The aim of the study was to evaluate the influence of mycorrhizal fungi (MF) and irrigation on biological properties of sweet pepper rhizosphere in organic field cultivation. For this purpose, MF were applied to plants in the form of commercial mycorrhizal inoculum (Rhizophagus aggregatus, R. intraradices, Claroideoglomus etunicatum, Endogone mosseae, Funneliformis caledonium, and Gigaspora margarita) and irrigation according to the combinations: mycorrhized plants (PM), mycorrhized and irrigated plants (PMI), and irrigated plants (PI). Plants without MF and irrigation served as the absolute control (P). The study used classic and molecular techniques, assessing catalase activity, biodiversity of soil microorganisms (soil DNA analysis), and the Community-Level Physiological Profiles (CLPP) analysis using Biolog EcoPlates. The highest catalase activity was recorded in the control and mycorrhized soil sample. The highest total number of bacteria was noted in the rhizosphere of control plants (P) and irrigated plants, while the lowest number in the rhizosphere of mycorrhized and irrigated plants. Plant irrigation contributed to the increase in the total number of fungi in the rhizosphere. The rhizospheric soil of PM and PMI were characterized by the highest utilization of amines, amides, and amino acids, whereas the lowest level of utilization was detected in the P and PI rhizospheres. The highest biodiversity and metabolic activity were observed in the rhizospheres from the PMI and PM samples, whereas lower catabolic activity were recorded in the P and PI rhizospheres. The mycorrhization of crops improved the biological properties of the rhizosphere, especially under conditions of drought stress.

The size and quality of the melon fruit yield depend on the cultivar, climatic and agronomic factors. A three-year field experiment investigated the effect of arbuscular mycorrhizal fungi (AMF) application and irrigation (IR) on the fruit yield of melon (Cucumis melo L. var. saccharinus Naud.) cultivars. The study was conducted on a certified organic farm located in south-eastern Poland (51.36° N, 22.83° E). The factors of the experiment were as follows: cultivar (Melba, Emir F1, Seledyn F1, Oliwin) and cultivation method (AMF and IR; AMF and non-IR; non-AMF and IR; non-AMF and non-IR as control). The dry matter (%), soluble solid (%), total sugar and reducing sugar (% fresh weight, FM), L-ascorbic acid (mg · 100 g⁻¹ FM), and carotenoid (mg · 100 g⁻¹ FM) contents of the fruit were determined. The highest total and marketable fruit yields were obtained using AMF and IR. Fruit from the AMF series (IR and non-IR) had the most carotenoids (respectively: 801.5 and 788.8 µg · 100 g⁻¹ FM). The fruits of the AMF and IR plants contained the most total sugars (5.98%) and reducing sugars (2.91%) compared to the others. The control plants had the lowest number of marketable fruit, total and marketable fruit yield, and accumulated the least L-ascorbic acid, total sugars and reducing sugars. We suggest that AMF and IR can be recommended as a practical agronomic solutions for the field cultivation of melon under temperate climate conditions.

The cultivation of catch crops left on the surface of the field in the form of mulch promotes sustainable farming practices, while protecting the biodiversity of agricultural landscape. The paper presents results of research from 2013–2016, aimed at determining the usefulness of catch crops of millet, buckwheat, white mustard, bird’s-foot and Egyptian clover for soil mulching in winter garlic cultivation. The effect of soil litter on the amount of garlic crop in cultivation for bunch harvest and nutritional value determined by chemical composition of edible parts was determined. In the edible part of garlic, the content of dry matter, total and reducing sugars, L-ascorbic acid, total ash, crude fiber, phenolic acids and essential oil was evaluated. The control consisted of plots without mulch plants. In the cultivation of garlic under organic mulch, there was no decrease in commercial yield and no negative competitive effect on yielding. Garlic plants cultivated with mulch plants were characterized by increased height and developed more leaves. The catch crops used in the form of mulch did not affect the dry matter and total ash content in garlic bulbs. In the cultivation with plant litter, the concentration of phenolic acids and essential oil in the leaves was higher and the content of crude fiber was lower, compared to the cultivation without litter. Biomass from catch crops from clover and mustard increased the content of L-ascorbic acid, at the same time reducing the content of total and reducing sugars in the edible part of garlic, except for mulch plants of the bean family. The chemical composition of garlic was affected by different thermal and precipitation conditions in the years of research. In 2016, the year with the highest total rainfall, plants accumulated more dry matter, L-ascorbic acid as well as total and reducing sugars than in 2014 and 2015, years with less rainfall. Our research indicates that there are prospects for practical application of catch crops in the form of mulch for garlic cultivation to enhance the level of nutrients, without compromising the yield.