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Within a framework of renewed interest in crambe ( Crambe abyssinica Hochst ex R.E. Fries) sourcing raw materials for the bio-based industry, the adaptability and productive performances of this oil crop have been evaluated under contrasting Mediterranean environments (i.e., a fertile site in the northern part of Po valley vs. a semi-arid site of southern Sicily) during two consecutive growing seasons, aiming at its possible stable introduction in this area. The trial set in northern Italy compared three commercial varieties of crambe (Galactica, Nebula and Mario) in spring sowing, while in southern Italy only the var. Mario was tested with autumn sowing. Regardless of location and variety, thermal time for maturity was quite stable (1200–1400 °C), and the crop provided satisfactory seed yields (grand mean 2.29 Mg hulled seeds ha −1 ), with average oil content of ∼400 g kg −1 (on dehulled seeds) and ∼52% of erucic acid. Significantly higher seed and oil yields were reached in northern than in southern Italy. Furthermore, crambe thermal use efficiency (THUE) was also higher in the north than in the south, possibly due to better environmental adaptability of the crop. The limited intraspecific variability within crambe was confirmed, with better productive performances showed by the domestic selection Mario. Promising traits were revealed in Nebula, showing greater seed weight, root length density and area, and thinner roots, although the root growth of crambe was generally modest compared with modern high erucic acid rapeseed hybrids. Available crambe varieties could be efficiently included in crop rotations across a wide range of environments within the Mediterranean basin. The short growth cycle represents an outstanding added value for this species, allowing the avoidance of prolonged drought and heat stress typical of late spring/early summer months under the Mediterranean climate. However, increased yields are needed to meet the market requests; nonetheless, the little genetic variability suggests that there is large scope for future breeding improvements, maybe exploiting advanced techniques to improve the existing genetic resources. [ABSTRACT FROM AUTHOR]

The aim of the present work was to evaluate the effect of soil water availability and nitrogen fertilization on yield, water use efficiency and agronomic nitrogen use efficiency of giant reed ( Arundo donax L.) over four-year field experiment. After the year of establishment, three levels for each factor were studied in the following three years: I 0 (irrigation only during the year of establishment), I 1 (50% ETm restitution) and I 2 (100% ETm restitution); N 0 (0 kg N ha −1 ), N 1 (60 kg N ha −1 ) and N 2 (120 kg N ha −1 ). Irrigation and nitrogen effects resulted significant for stem height and leaf area index (LAI) before senescence, while no differences were observed for stem density and LAI at harvest. Aboveground biomass dry matter (DM) yield increased following the year of establishment in all irrigation and N fertilization treatments. It was always the highest in I 2 N 2 (18.3, 28.8 and 28.9 t DM ha −1 at second, third and fourth year growing season, respectively). The lowest values were observed in I 0 N 0 (11.0, 13.4 and 12.9 t DM ha −1 , respectively). Water use efficiency (WUE) was significantly higher in the most stressed irrigation treatment (I 0 ), decreasing in the intermediate (I 1 ) and further in the highest irrigation treatment (I 2 ). N fertilization lead to greater values of WUE in all irrigation treatment. The effect of N fertilization on agronomic nitrogen use efficiency (NUE) was significant only at the first and second growing season. Giant reed was able to uptake water at 160–180 cm soil depth when irrigation was applied, while up to 140–160 cm under water stress condition. Giant reed appeared to be particularly suited to semi-arid Mediterranean environments, showing high yields even in absence of agro-input supply. [ABSTRACT FROM AUTHOR]

Highlights: [•] Monoecious and dioecious hemp were studied in Mediterranean semi-arid environment. [•] Later dioecious showed the highest aboveground and stem DM yield (tha−1) [•] WUE ranged between 2.73gl−1 in good water and 3.45gl−1 in water stress conditions. [•] Optimum of photosynthetic rate was achieved at 24°C. At 43°C hemp growth ceased. [•] As soil water availability increased, RUE increased and light extinction coefficient (k) decreased. [ABSTRACT FROM AUTHOR]