Influence of biochar, mycorrhizal inoculation and fertilizer rate on growth and flowering of pelargonium (Pelargonium zonale L.) plants

Peat is the most common substrate used in nurseries despite being a very expensive and a non-renewable material. Peat replacement with biochar could be a sound environmental practice, as it is produced from waste biomass, but evaluation of biochar as a potting substrate is needed. Ratios of peat:biochar of 100:0, 70:30, 30:70 (BC0, BC30, and BC70, respectively), two fertilizer rates (FERT1, FERT2), and arbuscular mycorrhizal fungi (AMF) inoculation were tested on potted Pelargonium plants. Plant growth, flowering, bio-physiological and nutritional responses, and root mycorrhization were evaluated. The BC30 mixture did not affect plant growth compared with pure peat. However, BC30 in combination with FERT2 treatment was more effective in enhancing nitrogen (N) and chlorophyll (CHL) leaf concentrations, and leaf and flower numbers. The BC70 mixture depressed plant growth, flowering traits, and root mycorrhization. Leaf N concentration was below the sufficiency range reported for Pelargonium growth. Leaf concentration of phosphorous (P) was adequate in pure peat and in BC30 but it dropped close to sub-optimal values in BC70. The pH value of the mixtures lowered P availability, though in BC30 the mycorrhizal activity could have allowed adequate P plant uptake. In BC70 plants, the deficiency of both N and P might be a reason for the observed growth reduction. The inoculation of the substrate with selected AMF improved plant growth (higher dry biomass, greater floral clusters, larger and more abundant leaves) and quality resulting in unstressed (lower electrolyte leakage and higher relative water content values) and greener leaves (low L∗ and C∗, high CHL content) and in more intensely colored flowers. We conclude that biochar can be applied in nursery/potted plant production provided that the proportion in the peat mixture does not exceed 30%. Furthermore, AMF inoculation contributed to achieving the best plant performance in 30% biochar amended medium

Nutritional, Biophysical and Physiological Characteristics of Wild Rocket Genotypes As Affected by Soilless Cultivation System, Salinity Level of Nutrient Solution and Growing Period

With the aim of defining the best management of nutrient solution (NS) in a soilless system for obtaining high quality baby-leaf rocket, the present study focuses on two wild rocket genotypes (“Nature” and “Naturelle”), grown in a greenhouse under two Southern Italy growing conditions—autumn-winter (AW) and winter-spring (WS)—using two soilless cultivation systems (SCS)—at two electrical conductivity values (EC) of NS. The SCSs used were the Floating System (FS) and Ebb and Flow System (EFS) and the EC values were 2.5 and 3.5 dS m−1 (EC2.5; EC3.5) for the AW cycle and 3.5 and 4.5 dS m−1 (EC3.5; EC4.5) for the WS cycle. The yield, bio-physical, physiological and nutritional characteristics were evaluated. Higher fresh (FY) (2.25 vs. 1.50 kg m−2) and dry (DY) (230.6 vs. 106.1 g m−2) weight yield, leaf firmness (dry matter, 104.3 vs. 83.2 g kg−1 FW; specific leaf area, 34.8 vs. 24.2 g cm−2) and antioxidant compounds (vitamin C, 239.0 vs. 152.7 mg kg−1 FW; total phenols, 997 vs. 450 mg GAE mg kg−1 FW; total glucosinulates-GLSs, 1,078.8 vs. 405.7 mg kg−1 DW; total antioxidant capacity-TAC, 11,534 vs. 8,637 μmol eq trolox kg−1 FW) and lower nitrates (1,470 vs. 3,460 mg kg−1 FW) were obtained under WS conditions. The seasonal differences were evident on the GLS profile: some aliphatic GLSs (gluconapoleiferin, glucobrassicanapin) and indolic 4-OH-glucobrassicin were only expressed in WS conditions, while indolic glucobrassicin was only detected in the AW period. Compared with EFS, FS improved leaf firmness, visual quality, antioxidant content (TAC, +11.6%) and reduced nitrate leaf accumulation (−37%). “Naturelle” performed better than “Nature” in terms of yield, visual quality and nutritional profile, with differences more evident under less favorable climatic conditions and when the cultivars were grown in FS. Compared to EC2.5, the EC3.5 treatment did not affect DY while enhancing firmness, visual quality, and antioxidant compounds (TAC, +8%), and reducing the nitrate content (−47%). The EC4.5 treatment reduced FY and DY and the antioxidant content. Despite seasonal climatic condition variability, FS and the moderate salinity level of NS (3.5 dS m−1) can be suggested as optimum

Harvest Season and Genotype Affect Head Quality and Shelf-Life of Ready-to-Use Broccoli

Pre-harvest climatic conditions and genotype may have important effects on head quality and post-harvest performance of fresh-cut broccoli. The present work evaluates the effect of the growing cycle (summer–autumn (SA), winter (W), winter–spring (WS), and spring (S)) and genotype on qualitative (dry matter, concentration of chlorophylls, carotenoids, and color) and antioxidative (ascorbic acid, dehydroascorbic acid, total phenol concentrations, and antioxidant capacity) traits of broccoli heads and minimally processed florets. The WS raw product showed the best color indices (L* = 38.6, C* = 9.3 and h° = 123.8) as well as the highest chlorophyll (0.23 µg mg−1 fresh weight) but the lowest total phenol concentration (5.5 µg mg−1 dry weight - DW), whereas the ascorbic acid level (2.3 µg mg−1 DW) was comparable to or lower than that the other growing cycles. The WS florets confirmed their best visual quality, even showing an improved total phenol level after 14 days of cold storage. The climatic conditions experienced by broccoli plants grown in SA, W, and S periods were stressful as they resulted in a slight reduction in the visual quality of the heads, though only the SA florets showed a distinctive decay during storage. The lower post-harvest performance of SA grown broccoli was confirmed in all the tested cultivars, despite ‘Naxos’ seeming more tolerant. On the contrary, the greatest content of ascorbic acid (3.2 µg mg−1 DW) in the W heads and of phenols (11.1 µg mg−1 DW) in S heads was maintained during storage, thus preserving floret color

Foliar Application of Protein Hydrolysates on Baby-Leaf Spinach Grown at Different N Levels

Surpluses of N are associated with environmental and health problems. To optimise N use and reduce nitrate accumulation in leafy species like spinach, the application of biostimulants is suggested. An experiment in controlled conditions (growth chamber/soilless) evaluated baby-spinach responses to two protein hydrolysates (PHs) from plant (legume, Trainer®) and animal (meat, Isabion®) sources, combined with three N rates: 2 (N2, deficient), 8 (N8, sub-optimal), and 14 (N14, optimal) mM of N. Biometrical and morphological traits of shoots and roots as well as the physio-metabolic (gas exchange, N assimilation, and NUtE), physical, mineral, and antioxidant profiles of leaves were assessed. The legume-PH boosts growth and yield only at the highest N conditions, while there was no effect at lower N rates. The legume-PH modulates root architecture and chlorophylls has positive responses only at optimal N availability, such as an increase in N uptake, leaf expansion, and photosynthetic activity at the canopy level. The PHs do not improve NUtE, leaf colour, consistency, cations, or antioxidants. Neither do PHs have any effect on reducing nitrate accumulation. Legume-PH improves N assimilation only at optimal N availability, while meat-PH does not, reaching the highest nitrate value at the highest N rate (2677 mg kg−1 fw), even if this value is under the EC limits for fresh spinach

Harvest and Post-Harvest Performance of Autumn-Winter Butterhead Lettuce as Affected by Nitrogen and Azoxystrobin Application

An autumn-winter trial was carried out in Southern Italy in open-field conditions on butterhead lettuce to investigate the effect of the nitrogen (N) fertilizer rate (0, 50, and 100 kg ha−1, N0, N50, N100) and the application of the azoxystrobin, sprayed twice in an earlier vs. a later application scheme, specifically at 65/85 or 65/100 days after transplantation. An untreated control was also included. The evaluation of the product quality was conducted on fresh and stored shredded leaves. The N50 was a suitable rate for autumn-winter butterhead lettuce, but it does not guarantee the color appearance of the fresh leaves (lowest h°, highest L*). Concerning post-harvest changes, the N50- and N100-product were less suitable for storage, accounting for higher decay of visual quality (h°) and physiological senescence (EL) indices. Irrespective of N rate and application time, azoxystrobin improved growth and yield (+16%), visual (lower L*, higher h°, and chlorophylls), and nutritional (higher carotenoids and antioxidant capacity) quality of the fresh leaves. The application of azoxystrobin improved the shelf-life of butterhead lettuce leaves, by keeping higher turgidity (RWC), lower color decay (CHLs, h°), and higher nutritional value (carotenoids), and by limiting the browning spreading in shredded leaves

Foliar Application of Protein Hydrolysates on Baby-Leaf Spinach Grown at Different N Levels

Surpluses of N are associated with environmental and health problems. To optimise N use and reduce nitrate accumulation in leafy species like spinach, the application of biostimulants is suggested. An experiment in controlled conditions (growth chamber/soilless) evaluated baby-spinach responses to two protein hydrolysates (PHs) from plant (legume, Trainer®) and animal (meat, Isabion®) sources, combined with three N rates: 2 (N2, deficient), 8 (N8, sub-optimal), and 14 (N14, optimal) mM of N. Biometrical and morphological traits of shoots and roots as well as the physio-metabolic (gas exchange, N assimilation, and NUtE), physical, mineral, and antioxidant profiles of leaves were assessed. The legume-PH boosts growth and yield only at the highest N conditions, while there was no effect at lower N rates. The legume-PH modulates root architecture and chlorophylls has positive responses only at optimal N availability, such as an increase in N uptake, leaf expansion, and photosynthetic activity at the canopy level. The PHs do not improve NUtE, leaf colour, consistency, cations, or antioxidants. Neither do PHs have any effect on reducing nitrate accumulation. Legume-PH improves N assimilation only at optimal N availability, while meat-PH does not, reaching the highest nitrate value at the highest N rate (2677 mg kg−1 fw), even if this value is under the EC limits for fresh spinach

Characterization of targeted phenolic compounds in globe artichoke heads and waste from vegetatively and "seed"-propagated genotypes

In the globe artichoke, both the edible portion and the waste biomass are recognized as valuable sources of bioactive compounds. For this study, heads with 30 cm-long floral stems including two to three leaves were harvested from five genotypes, which included two traditional vegetative-propagated varietal types ("Brindisino" and "Violetto di Foggia") and three "seed"-propagated hybrids ("Tempo", "Opal", and "Madrigal"). The study aimed to determine the total and individual polyphenolic concentrations (measured spectrophotometrically and using HPLC) and antioxidant activity (AA) in different artichoke parts, namely the "hearts" (H), head waste (HW), stem waste (SW), and leaf waste (LW). "Brindisino" SW exhibited the highest accumulation of luteolin (26,317 mg kg(-1) F.W.), while "Tempo" H displayed the highest cynarin content (190 mg kg(-1) F.W.). "Tempo" HW and H showed the highest levels of apigenin (640 mg kg(-1) F.W.), and the greatest source of chlorogenic acid was found in the HW of "Opal" and the H of "Brindisino" (4300 mg kg(-1) F.W.). The hybrids generally exhibited lower total polyphenolic concentrations than the traditional genotypes, particularly evident in the LW. The SW demonstrated the highest concentration of total polyphenols (18,000 mg kg(-1) F.W.), followed by the edible H and non-edible HW (12,000 mg kg(-1) F.W.), while the LW exhibited the lowest concentration (2000 mg kg(-1) F.W.). Interestingly, the AA did not precisely align with the total polyphenolic concentration, showing slight variations between the examined parts and genotypes

Growth, N uptake and N critical dilution curve in broccoli cultivars grown under Mediterranean conditions

Adequate nitrogen (N) availability must be ensured in broccoli as it is a high N demand crop, however the N not taken up may cause ground and surface water pollution. Both species-specific growth and N demand predicting models could be useful for rational N fertilization management. Two field experiments were conducted on three broccoli cultivars grown at different N fertilization levels [0 (N0), 75 (N75), and 100 (N100) kg ha−1] and under Southern Italian/Mediterranean conditions (i) to study the growth and the N uptake and (ii) to determine the critical N dilution curve for this crop. Nitrogen fertilization prompted crop growth during the linear phase (growth rate ∼9.0 g m-2 d-1 of dry weight - DW) as a result of the enhancement of the intercepted photosynthetically active radiation (IPAR) and of the efficiency in using IPAR for producing dry biomass (RUE). However, the effect of N fertilization on final aboveground dry biomass production (ADW) (∼4.6 Mg ha-1) was affected by the cultivar specific response to the seasonal variability of the temperature time course. In the ‘Ironman’ cultivar, N nutrition was less effective under suboptimal temperatures, in enhancing ADW and N uptake, because of the reduced leaf growth and IPAR. On the contrary, in ‘Naxos’ and ‘Parthenon’ N fertilization was more effective in limiting the effect on plant growth of the sub-optimal temperatures. Under such conditions, despite a slow reduction in IPAR, both cultivars enhanced RUE, with a concomitant increase in specific leaf N. ‘Naxos’ and ‘Parthenon’ gave higher and more stable yields, ADW, harvest index (HI) and N uptake over the two seasons. Among the N rates, the best N use efficiency in terms of yield (Partial Factor Productivity) and head dry weight gain (Agronomical NUE) per unit of applied N fertilizer, was obtained with the rate of 75 kg ha-1. At the highest N rate, ADW and yield slightly increased, with no effect on HI. Hence, this rate might be considered close to the optimal under the conditions of the experiment. Two cultivar-specific N dilution curves for broccoli have been proposed to account for the difference which emerged between’ Parthenon’ and the other broccoli cultivars mainly for the differences related to the proportion of stems on ADW. Both curves underline that this crop maintains a relatively high fraction of photosynthetically active tissue approaching the harvest compared to other brassicas