Search

The aim of the present work was to assess the leaf area duration (LAD) and the radiation use efficiency (RUE) of six warm-season perennial biomass grasses (PBGs) in a two-year field trial in the semiarid Mediterranean climate under different soil water availability. Two ecotypes of giant reed (Arundo donax L., ARCT and ARMO), one ecotype of African fodder cane (Saccharum spontaneum L. subsp. aegyptiacum (Willd.) Hack., SAC) and three hybrids of Miscanthus (the commercial M. × giganteus J.M. Greef, Deuter ex Hodk., Renvoize, M × G, and two new seed-based hybrids, GNT9 and GNT10) were compared under three levels of soil water availability: rainfed, 50% and 100% of maximum crop evapotranspiration (ETm) restoration. The determination of RUE of perennial plants is controversial and has led to contrasting results in past studies. In the present work, LAD and RUE differed among crops and irrigation regimes, being positively affected by supplemental water inputs. SAC, ARCT and ARMO showed both high LAD and RUE, which determined the high biomass yield than both the commercial M × G and the improved Miscanthus hybrids GNT9 and GNT10. RUE was particularly high and less affected by soil water availability during the mid-season, while the effect of irrigation and the differences among the genotypes were larger during the late season. Adequate biomass yield can be achieved by sub-optimal soil water availability, thus reducing the water footprint and increasing the sustainability of these biomass perennial grasses selected for the Mediterranean climate. [ABSTRACT FROM AUTHOR]

To date, economically and energy-costly vegetative propagation using rhizomes and tissue culture are the only options for the cultivation of Miscanthus spp. Some genotypes of miscanthus produce fertile seeds, offering a valid alternative to vegetative propagation. A preliminary study has been conducted on the seeds of two hybrids of miscanthus obtained via interspecific cross-pollination between M. sacchariflorus and M. sinensis: 'GRC14' (maternal: M. sacchariflorus) and 'GRC10B' (maternal: M. sinensis). Seeds were assessed for germination traits in a laboratory (at 25 °C in the dark) just after panicle harvest, and during 1-year storage at room temperature or at 8 °C. In a second experiment, the effects of gibberellic acid (GA3) solution at different concentrations (0, 50, 100, 300, 500 ppm) on the germination of freshly matured seeds were assessed. Poor germination just after harvest (<30%) indicates the occurrence of a physiological dormancy. Indeed, two months later, germination rose up to 76.7% in 'GRC14' and 50.8%, in 'GRC10B', and peaked at 95.6% in 'GRC14' and at 78% in 'GRC10B', 6 months after harvest. After a total of 12 months, germination was significantly reduced in both hybrids (≈60%). Seeds stored at room temperature lost dormancy earlier than those stored at 8 °C. Overall, germination was significantly improved by GA3, but the extent of the GA effect was genotype-dependent. In conclusion, a low establishment rate may result from direct seeding when fresh seed is used in the field. In this case, the use of GA3 is a possible strategy to ameliorate the impact of dormancy on seed germination. In the case of delayed sowings in late winter–early spring, seeds stored at room temperature after harvest may better perform than those stored at 8 °C. [ABSTRACT FROM AUTHOR]

Castor (Ricinus communis L.) is an oilseed species that can be grown as a semi-perennial in Mediterranean environments, including the coastal areas of Sicily. The present study investigated the optimization of cultivation techniques for castor, with the crop being maintained over a two-year period, through the evaluation of different agronomical inputs in order to increase seed yield. The effects of irrigation (I) and nitrogen fertilization (N) on the seed and oil yield and their components were assessed in castor cultivated in a typical semi-arid environment. Four levels of irrigation (I0, I30, I60, and I100: 0, 30, 60, and 100% of crop evapotranspiration—ETm restoration, respectively) as the main plot and three levels of nitrogen fertilization (N) (0, 60, and 120 kg N ha−1) as the sub-plot were considered. Irrigation mostly affected the number of racemes per plant, the number of capsules per raceme, and the seed weight. The oil content was, on average, 39.2% and 45.6% for the first and second year, respectively. The highest seed yield was obtained by I100N120 treatment (4154.0 kg ha−1); however, the combination of a high soil nitrogen level (N120) and medium water availability (I60) resulted in satisfactory seed and oil yields. The reduction in the irrigation water to an intermediate level could be also an environmentally friendly strategy not significantly affecting yields. [ABSTRACT FROM AUTHOR]

In this study, the allelochemical-induced effects of the leaf water extract of hemp (Cannabis sativa) on seed germination and seedling growth were investigated in durum wheat (Triticum durum) cv. Mongibello and barley (Hordeum vulgare) cv. Alamo. The seeds were imbibed in 25%, 50%, 75%, or 100% solution concentrations, obtained from a 2% hemp leaf extract, and they were germinated at 20 and 10 °C. The 2% extract stock solution (i.e., 100% solution concentration) was obtained by extracting 20 g of leaf powder in 1 L distilled water (2%, w/v). A control of seeds imbibed in distilled water was considered. Germination was scored daily and at the end of the germination test, the final germination percentage (FGP), mean germination time (MGT), germination index (GI), and vigor index (VI) were calculated. The radicles and shoots of the germinated seeds of both species were also measured for their length and weight. The analyses revealed the presence of phenols in the hemp leaf extract, which were the highest in the 100% concentration (13.14 ± 0.20 mg gallic acid equivalent-GAE g−1 extract). At 20 °C, increasing the concentration had either minor (in wheat) or no effects (in barley) on the seed germination. At 10 °C, the germination was reduced by the increasing concentration, suggesting a potential allelopathic effect of the extract. However, at 100% concentration, the seeds germinated significantly better that those at 75% concentration. At 20 °C, increasing concentration progressively depressed both the radicle and shoot elongation in both species. At 10 °C, the radicle elongation was depressed by the extract, irrespective of the concentration, whilst the shoots were as long as those of the control in wheat, and smaller at the 50 and 75% concentrations in barley. We can conclude that the water extract of hemp leaves can have a negative impact on wheat and barley seed germination and seedling growth, particularly at temperatures below optimal. However, the high concentration of phenols in the extract may stimulate seed germination and seedling growth. Thus, in semi-arid areas, such as those of the Mediterranean regions, sowings of wheat and barley after hemp at an optimal (i.e., 20 °C) or nearly optimal temperature are recommended in order to minimize the combined stressing effects of the temperature and allelopathic leaf extract upon plant establishment, which may limit a successful crop establishment. [ABSTRACT FROM AUTHOR]

Some physiological, oxidative, and antioxidant enzymatic patterns were assessed in plants of three local Sicilian landraces of long shelf-life tomatoes ('Custonaci', 'Salina', and 'Vulcano'), as compared to the commercial tomato hybrid 'Faino' (control). Three water treatments were considered in open-field: DRY (no irrigation); IRR (long-season full irrigation); REW (drought/rewatering cycles). During the growing season, soil water deficit (SWD) was estimated, and relative water content (RWC), specific leaf area (SLA), proline and malondialdehyde (MDA) content, and glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD) activities were measured in leaves. Differently from control, RWC in local landraces exhibited a similar pattern in REW and DRY, indicating a low capacity to re-hydrate after rewatering. Positive correlation of proline content vs. SWD in all local landraces highlights an osmotic adjustment occurring in these tomatoes in response to limited soil water content. Long shelf-life tomatoes suffered minor oxidative stress due to severe soil water deficit, as revealed by the lower levels of MDA with respect to the control. Significant correlation of CAT vs. SWD for all tomatoes indicates that this antioxidant enzyme, among those analyzed, may be considered as a biomarker for a water stress condition more than for oxidative stress due to water deficit. [ABSTRACT FROM AUTHOR]

The Mediterranean long shelf-life tomato (or long storage tomato) is a plant traditionally cultivated under no irrigation in the Southern regions of Italy, whose fruits have typical high sensory and nutritional quality. However, yield levels are kept low under current cultivation conditions. In this study, the effects of repeated cycles of drying and rehydration on crop productivity and nutritional quality of fruits in terms of polyphenols and carotenoids content were assessed in long shelf-life tomatoes cultivated in a typical semi-arid area of Southern Italy. The three local Sicilian landraces 'Custonaci', 'Salina' and 'Vulcano', and the commercial tomato hybrid 'Faino' (control) were submitted to three irrigation treatments: DRY (no irrigation); IRR (long-season full irrigation); REW (drought/rewatering cycles). Total 450, 4710, and 1849 m3 ha−1, were distributed in DRY, IRR, and REW, respectively. At harvest, fruit yield, polyphenols (as total, flavonoids, and hydroxycinnamoyl quinic acids-HCQA), and carotenoids contents (lycopene and β-carotene) were measured. All cultivars benefitted from very limited irrigation in REW, raising their productivity (up to +147% in 'Vulcano') with respect to that of plants overstressed in DRY. Irrigation water use efficiency in REW was higher than that in IRR. Water shortage in REW led to a polyphenols content of fruits that was slightly lower (171.1 μg g−1) than that in DRY, but higher than that in IRR (116.8 μg g−1). All local landraces had greater contents (>160 μg g−1) than control (113.0 μg g−1). Under REW and DRY, the two landraces 'Salina' and 'Vulcano' produced fruits with the same polyphenols and flavonoids contents. Overall, the two water stressed treatments (DRY and REW) did not differ for HCQA content (>66 μg g−1), which was significantly higher than that in the irrigated plots (<50.55 μg g−1). Lycopene content in DRY and REW exceeded 100 μg g−1; among local types, 'Vulcano' exhibited the highest content (106.7 μg g−1). The β-carotene content did not change in 'Custonaci' and 'Salina', whereas in 'Vulcano' it was greater in DRY and REW. Only in 'Faino' water limitation in REW exerted a clear promoting effect on β-carotene content of fruits. The results of the present study reveal how rewatering after long-lasting drought periods is beneficial to long shelf-life tomatoes in terms of productivity. Appropriate drought cycles in REW may also help the fruits to retain high nutritional levels. [ABSTRACT FROM AUTHOR]

Within the project "BIOSEA" funded by the Italian Ministry of Agriculture and Forestry, a preliminary laboratory test was conducted to assess the variability for cold tolerance during germination in 30 cultivars of biomass sorghum, among fiber and sweet types. Seed germination (%) and mean germination time (MGT) were examined at seven constant temperatures (from 8 °C to 35 °C) and base temperature (Tb) and thermal time (θT) for 50% germination were calculated. A wide genetic diversity in the germination response of sorghum was ascertained at 8 °C (CV 45%) and 10 °C (CV 25.4%). At 8 °C, in cultivars of 'Padana 4', 'PR811F', 'PSE24213', 'PR849' and 'Zerberus', seed germination exceeded 80%. Seeds of 'Zerberus' were also the fastest, requiring less than 13 days for final germination at this low temperature. Great differences were found in Tb and θT among cultivars. Tb varied between 7.44 °C ('PR811F') and 13.48 °C ('Nectar'). Thermal time (θT) was, on average, 24.09 °Cd−1, and ranged between 16.62 ('Nectar') and 33.42 °Cd−1 ('PSE24213'). The best combination of the two germination parameters (i.e., low Tb and θT) corresponded to 'Zerberus', 'Sucrosorgo 506', 'Jumbo' and 'PR811F'. Accordingly, these cultivars are more tolerant to cold stress during germination and, thus, more adapt to early spring sowings in Mediterranean areas (March-April). Cultivars 'PR811F' (fiber type) and 'Sucrosorgo 506' (sweet type) also combine high cold tolerance with good productivity in terms of final dry biomass, as assessed in open-field conditions (late spring sowing). The genetic variation in the germination response to a low temperature is useful for the identification of genotypes of sorghum suitable to early sowings in semi-arid areas. Selection within existing cultivars for cold tolerance during germination may also contribute to the expansion of biomass sorghum into cooler cultivation areas, such as those of Northern Europe, which are less suitable to this warm season crop. [ABSTRACT FROM AUTHOR]