Rocco Bochicchio

Measuring canopy height is important for phenotyping as it has been identified as the most relevant parameter for the fast determination of plant mass and carbon stock, as well as crop responses and their spatial variability. In this work, we develop a low-cost tool for measuring plant height proximally based on an ultrasound sensor for flexible use in static or on-the-go mode. The tool was lab-tested and field-tested on crop systems of different geometry and spacings: in a static setting on faba bean (Vicia faba L.) and in an on-the-go setting on chia (Salvia hispanica L.), alfalfa (Medicago sativa L.), and wheat (Triticum durum Desf.). Cross-correlation (CC) or a dynamic time-warping algorithm (DTW) was used to analyze and correct shifts between manual and sensor data in chia. Sensor data were able to reproduce with minor shifts in canopy profile and plant status indicators in the field when plant heights varied gradually in narrow-spaced chia (R² = 0.98), faba bean (R² = 0.96), and wheat (R² = up to 0.99). Abrupt height changes resulted in systematic errors in height estimation, and short-scale variations were not well reproduced (e.g., R² in widely spaced chia was 0.57 to 0.66 after shifting based on CC or DTW, respectively)). In alfalfa, ultrasound data were a better predictor than NDVI (Normalized Difference Vegetation Index) for Leaf Area Index and biomass (R² from 0.81 to 0.84). Maps of ultrasound-determined height showed that clusters were useful for spatial management. The good performance of the tool both in a static setting and in the on-the-go setting provides flexibility for the determination of plant height and spatial variation of plant responses in different conditions from natural to managed systems.

Roots play a key role in withstanding wheat abiotic stress. In this work, we phenotyped seedling root morphology of two semi-dwarf bread wheat cultivars, the Chinese cv Lankaodali and the Italian cv Rebelde, under the hypothesis that these two genotypes have contrasting root traits and could be used as donors in breeding programs. Root development was compared in a semi-hydroponic screening, where full-strength (FS) vs. half-strength (HS) complete Hoagland’s solution represented high and moderate nutrient availability, and a screening comparing HS solution with tap water corresponding to a condition of nutrient starvation. Genotypes were further compared in soil under full watering (100% of field capacity) vs. drought stress (50% of field capacity). Lankaodali outperformed Rebelde by producing 50% more leaf mass and 70% more root mass in FS solution, 125% more leaf mass and 106% more root mass in HS solution, and 65% more leaf mass and 36% more root mass under nutrient starvation. This cv also showed a positive correlation between leaf mass and root length and mass (between r = 0.82–0.9 and r = 0.83–0.87, respectively, p < 0.05). In the soil screening experiment, Lankaodali produced more biomass than Rebelde regardless of water availability, 48% more leaf mass, 32% more root mass, and 31% more absolute rhizosheath mass (average across water availability treatments). Lankaodali proved to be more responsive than Rebelde to both water and nutrient availability. High values of broad-sense heritability—ranging between 0.80 for root mass and 0.90 for length in a hydroponic screen and 0.85 for rhizosheath size in soil—indicate that these traits could be useful for breeding.

Insect larval frass has been proposed as a fertilizer and amendment, but methods for testing its effects on plants are poorly developed and need standardization. We obtained different types of black soldier fly (Hermetia illucens) frass via the factorial combination of (a) two insect diets, as follows: G (Gainesville = 50% wheat bran, 30% alfalfa meal, 20% maize meal) and W (43% sheep whey + 57% seeds); (b) two frass thermal treatments: NT = untreated and T = treated at 70 °C for 1 h. We tested the effects on the germination of cress (Lepidium sativum L.) and wheat (Triticum durum Desf.) by applying 1:2 w:w water extracts at 0, 25, 50, 75 and 100% concentration. Standardizing frass water content before extraction affected chemical composition. Frass extracts showed high electrical conductivity (8.88 to 13.78 mS cm⁻¹). The W diet was suppressive towards Escherichia coli and showed a lower content of nitrates (e.g., WNT 40% lower than GNT) and a concentration-dependent phytotoxic effect on germinating plants. At 25% concentration, germination indices of G were 4.5 to 40-fold those at 100%. Root and shoot length and root hair area were affected by diet and concentration of frass extracts (e.g., root and shoot length in cress at 25% were, respectively, 4.53 and 2 times higher than at 100%), whereas the effects of the thermal treatment were few or inconclusive. On barley (Hordeum vulgare L.) grown in micropots on a silty loam soil, root mass was reduced by 37% at high extract concentration. A quick procedure for root hair surface area was developed based on the geographic information system (GIS) and may provide a fast method for incorporating root hair phenotyping in frass evaluation. The results indicate that below-ground structures need to be addressed in research on frass effects. For this, phyotoxicity tests should encompass different extract dilutions, and frass water content should be standardized before extraction in the direction of canonical procedures to allow comparisons.

In dual-purpose cereal systems, the co-production of fodder and grain can increase farm profitability and reduce farming risks. Our work evaluated shoot and root growth in durum wheat (Triticum durum Desf.) under dual-purpose management in a medium-high rainfall area of southern Italy. We compared a modern variety (Core) with a tall ancient variety (Saragolle lucana) under traditional (NDP) and dual-purpose (DP) management and tested the hypothesis that clipping plants during the vegetative stage would reduce root growth and dewatering before anthesis, which is advantageous in drought-prone environments. Experiments were conducted in Bella (PZ), Basilicata region, southern Italy (40°42′ N, 15°32′ E) on a clay loam soil in 2021 in a split-plot design on 2 × 2 main plots and 1 × 2 split-plots with 6 replicates. The DP treatment consisted of simulated grazing by clipping plants at 5 cm from the ground 3 months after sowing (at first hollow stem). Forage Biomass was not different at p = 0.05 between varieties, with an average of 0.58 t ha⁻¹ DM. Grain yield was not penalized by clipping (p = 0.05) and did not differ significantly between varieties. SPAD was always lower in the Saragolle variety and lowered by clipping. Defoliation delayed phenology in both cultivars but did not reduce the final number of spikes per square meter. Stomatal conductance was correlated to temperature, did not differ between cultivars, and was not influenced by clipping. Soil water depletion was monitored in modern wheat from the booting stage to the beginning of grain filling. Clipping did not result in a reduction in pre-anthesis water depletion, possibly due to evaporative losses. Root density was markedly reduced by clipping in core variety between 0.20 and 0.60 m and much less in Saragolle. Unclipped Saragolle produced thicker roots and higher root masses compared to clipped plants. Defoliated Saragolle shifted to finer roots, reducing root mass more than length. This may have reduced the metabolic cost of soil exploration, thereby increasing root foraging efficiency.

Ancient wheats may be a source of traits that are useful for the tolerance of climate change foreseen conditions of raising temperatures and low water availability. Previous research has shown a fine root system and a high mass of rhizosheath per unit root mass in the italian durum wheat (Triticum durum Desf) landrace Saragolle Lucana, and this may be relevant for successfully facing adverse conditions during seedling establishment. We investigated the effect of soil water shortage in Saragolle seedlings on root architecture, rhizosheath formation and biomass allocation. Pot experiments were conducted by comparing two levels of soil available water content (AWC): WW (100% of AWC) and DS (50% of AWC). Phenology was delayed by eight days in DS and above and belowground traits were measured at Zadoks 1.3 for each treatment. Biometric data collected at the same phenological stage show that DS plants did not reach the levels of biomass, surface area and space occupation of WW even after attaining the same developmental stage. Namely, plant dimensions were lower at low soil water availability, with the exception of rhizosheath production: DS yielded a 50% increase in rhizosheath mass and 32% increase in rhizosheath mass per unit root mass. The proportion of plant mass reduction in DS was 29.7% for aboveground parts and 34.7% for roots, while reductions in leaf and root surface areas exceeded 43%. The root/shoot mass and area ratios were not significantly different between treatments, and a higher impact on aboveground than on belowground traits at reduced available water was shown only by a lower ratio of shoot height to root depth in DS than in WW. Increases in rhizosheath in absolute and relative terms, which were observed in our experiment in spite of smaller root systems in the ancient durum wheat variety Saragolle lucana at DS, may provide an interesting trait for plant performance in conditions of low soil water availability both for water-related issue and for other effects on plant nutrition and relations with the rhizosphere.

To make feasible the crewed missions to the Moon or Mars, space research is focusing on the development of bioregenerative life support systems (BLSS) designed to produce food crops based on in situ resource utilisation (ISRU), allowing to reduce terrestrial input and to recycle organic wastes. In this regard, a major question concerns the suitability of native regoliths for plant growth and how their agronomic performance is affected by additions of organic matter from crew waste. We tested plant growth substrates consisting of MMS-1 (Mars) or LHS-1 (Lunar) simulants mixed with a commercial horse/swine monogastric manure (i.e., an analogue of crew excreta and crop residues) at varying rates (100:0, 90:10, 70:30, 50:50, w/w). Specifically, we measured: (i) lettuce (Lactuca sativa L. cultivar ‘Grand Rapids’) growth (at 30 days in open gas exchange climate chamber with no fertilisation), plant physiology, and nutrient uptake; as well as (ii) microbial biomass C and N, enzymatic activity, and nutrient bioavailability in the simulant/manure mixtures after plant growth. We discussed mechanisms of different plant yield, architecture, and physiology as a function of chemical, physico-hydraulic, and biological properties of different substrates. A better agronomic performance, in terms of plant growth and optically measured chlorophyll content, nutrient availability, and enzymatic activity, was provided by substrates containing MMS-1, in comparison to LHS-1-based ones, despite a lower volume of readily available water (likely due to the high-frequency low-volume irrigation strategy applied in our experiment and foreseen in space settings). Other physical and chemical properties, along with a different bioavailability of essential nutrients for plants and rhizosphere biota, alkalinity, and release of promptly bioavailable Na from substrates, were identified as the factors leading to the better ranking of MMS-1 in plant above and below-ground mass and physiology. Pure Mars (MMS-1) and Lunar (LHS-1) simulants were able to sustain plant growth even in absence of fertilisation, but the amendment with the monogastric manure significantly improved above- and below-ground plant biomass; moreover, the maximum lettuce leaf production, across combinations of simulants and amendment rates, was obtained in treatments resulting in a finer root system. Increasing rates of monogastric manure stimulated the growth of microbial biomass and enzymatic activities, such as dehydrogenase and alkaline phosphomonoesterase, which, in turn, fostered nutrient bioavailability. Consequently, nutrient uptake and translocation into lettuce leaves were enhanced with manure supply, with positive outcomes in the nutritional value of edible biomass for space crews. The best crop growth response was achieved with the 70:30 simulant/manure mixture due to good availability of nutrients and water compared to low amendment rates, and better-saturated hydraulic conductivity compared to high organic matter application. A 70:30 simulant/manure mixture is also a more sustainable option than a 50:50 mixture for a BLSS developed on ISRU strategy. Matching crop growth performance and (bio)chemical, mineralogical, and physico-hydraulic characteristics of possible plant growth media for space farming allows a better understanding of the processes and dynamics occurring in the experimental substrate/plant system, potentially suitable for an extra-terrestrial BLSS.

Changes in root organization and colonization could be relevant for wheat’s (Triticum durum Desf.) response to F. culmorum-induced crown rot disease (FCR). We investigated the biocontrol and biostimulant efficiency of seeds coated with T. harzianum T-22 (T-22) of four tetraploid wheat seedlings (ancient Saragolle Lucana and modern Creso, Simeto, and Ciclope). In an in vitro experiment, T-22 repressed F. culmorum mycelium growth by over 50% due to the probable combination of competition for nutrients, mycoparasitism, and antibiosis. The seed germination rate was not significantly affected by T-22 while the F. culmorum-induced decrease in emergence was attenuated in the presence of T-22. Ultimately, an improvement in growth was observed by comparing treated and control seedlings at 21 days after sowing. Inoculation with T-22 resulted in Saragolle Lucana seedlings being 4.69 cm higher while Ciclope and Simeto had main roots that were 9.96 and 8.13 cm longer than the control, respectively. Treated and infected Simeto seedlings were 3.75 cm higher and had roots that were 14.45 cm longer than the control, with little contemporary dense coiling colonization by T-22, like Saragolle Lucana. Seed coating induced the best performance regarding seedling growth and the ability to control the pathogen in Simeto (disease severity reduction rate (DDR) of 20%). The pathogenicity of F. culmorum was reduced in all four durum wheats, although it was highly susceptible to FCR. Ciclope, studied for the first time, showed a decrease in disease incidence from 100 ± 0.00% to 56.67 ± 9.13% and a 30% DDR. The seed coating influenced the seedlings’ response to FCR due to T-22’s different colonization actions. This study provides new explanations for the diverse responses of ancient and modern tetraploid wheat to F. culmorum mediated by T-22 inoculation via seed coating.

Early root traits and allometrics of wheat are important for competition and use of resources. They are under-utilized in research and un-explored in many ancient wheats. This is especially true for the rhizosheath emerging from root-soil interactions. We investigated root morphology, root/shoot relations and the amount of rhizosheath of four tetrapoid wheat seedlings (30 days after emergence): the italian landrace Saragolle Lucana and modern varieties Creso, Simeto and Ciclope, and tested the hypothesis that inoculation with Trichoderma harzianum T-22 (T-22) enhances rhizosheath formation and affects wheat varieties differently. Overall growth of non-inoculated plants showed different patterns in wheat varieties, with Saragolle and Ciclope at the two extremes: Saragolle invests in shoot rather than root mass, and in the occupation of space with highest (p < 0.05) shoot height to the uppermost internode (5.02 cm) and length-to-mass shoot (97.8 cm g⁻¹) and root (more than 140 m g⁻¹) ratios. This may be interpreted as maximizing competition for light but also as a compensation for low shoot efficiency due to the lowest (p < 0.05) recorded values of optically-measured chlorophyll content index (22.8). Ciclope invests in biomass with highest shoot (0.06 g) and root (0.04 g) mass and a thicker root system (average diameter 0.34 mm vs. 0.29 in Saragolle) as well as a highest root/shoot ratio (0.95 g g⁻¹ vs. 0.54 in Saragolle). Rhizosheath mass ranged between 22.14 times that of shoot mass in Ciclope and 43.40 in Saragolle (different for p < 0.05). Inoculation with Trichoderma increased the amount of rhizosheath from 9.4% in Ciclope to 36.1% in Simeto and modified root architecture in this variety more than in others. Ours are the first data on roots and seedling shoot traits of Saragolle Lucana and of Trichoderma inoculation effects on rhizosheath. This opens to new unreported interpretations of effects of Trichoderma inoculation on improving plant growth.

Chia (Salvia hispanica L.) seeds are considered a superfood, but research on vegetative biomass uses is scarce. We conducted a two-year trial under the hypothesis that short-day flowering black chia would provide quality forage at high latitudes and tested sowing density (D1 = 125, D2 = 25, D3 = 8 and D4 = 4 plants m⁻²) and top-dressing N fertilization (N = 0, N = 20 kg ha⁻¹) at three stages (EV = early vegetative, LV = late vegetative and EF = early flowering). Forage yield reached 9.0 and 5.64 t ha^-1 of total and 2.07 and 1.56 t ha⁻¹ of leaf dry mass at EF in 2013 and 2014, respectively. High plant density corresponded to higher biomass but to lower plant relative growth rate, stem diameter, branching, proportion of leaves and lipid and crude protein content. Crude protein declined from 18% at EV to about 8% at EF and was lower in D1 than in D4. Lipids ranged between 33.83 g kg⁻¹ (D4, EV) and 17.34 g kg⁻¹ (D1, EF) (p < 0.005). N topdressing affected forage quality but not yield. Alpha-linolenic acid was the most abundant fatty acid (FA) (608 g kg⁻¹ FA at EV). The long vegetative growth of short-day flowering chia in southern Europe is favorable to fodder production, and management should be optimized by seeking balance between growth rate and stand density while optimizing vegetative stage growth for the highest forage quality.