F. Gresta

Saffron, An Alternative Crop for Sustainable Agricultural Systems: A Review

Saffron (Crocus sativus L.) is an autumnal flowering geophite whose dried stigmas, well known for their aromatic and colouring power, have been used since immemorial time as a spice in human nutrition, for medicinal purposes and as a dye. Many doubts remain on its origin; it was probably selected and domesticated in Crete during the Late Bronze Age. Saffron is an autotriploid geophyte species, self- and out-sterile and mostly male-sterile and therefore unable to produce seed, that reproduces by means of corms. Furthermore, it has a reverse biological cycle compared with the majority of cultivated and spontaneous plants: flowering first in October–November, then vegetative development until May, which means that the vegetative development is not directly important for production of stigmas, but for the production of new corms. Due to its unique biological, physiological and agronomic traits, saffron is able to exploit marginal land and to be included in low-input cropping systems, representing an alternative viable crop for sustainable agriculture. Notwithstanding this great potential and the considerable increase in new generation consumer demand for saffron, the future of the plant is still uncertain. Indeed, the main obstacles to saffron production are: (1) the limited areas of cultivation in countries where it is traditionally grown, (2) the great amount of sophisticated spice, (3) management techniques executed by hand, and (4) the very high price of the spice. Here we review the main biological, genetic and ecological traits associated with agronomic management techniques of saffron in relation to environmental conditions. Colour, taste and aroma are the essential features on which the quality of saffron stigmas is founded. In turn, these aspects are strictly connected with the biomolecular composition of the stigmas, namely, the carotenoids and their derivatives. With this in mind, the biosynthetic pathway that leads to the formation of saffron secondary metabolites and their abundance in the spice is presented, together with the biomedical properties commonly associated with saffron. Furthermore, a detailed overview of the more recent instrumental methods to assess the quality of saffron, strictly from a chemical point of view, will be discussed.

Weed control strategies for grain legumes

There has been increasing interest in sustainable weed management in low-input farming systems. In an integrated approach, the development of cropping systems such as appropriate spatial arrangement and efficient tillage will help crops themselves to compete with weeds. With this aim, we investigated the strategic use of plant lodging combined with mechanical weed treatment to improve crop competitiveness and reduce the use of herbicides. We studied weed infestation and grain yield of three grain legumes, field bean, chickpea and field pea, grown according to different plant lodgings (narrow, wide and twin rows) and weed suppression methods: untreated, chemical and mechanical control. In the two years of the trial, two different weed infestation levels were observed due to different meteorological conditions. Our results show that the different crops showed different competitive behaviours, especially in weedy conditions. Indeed, in the bean plots, weed infestation was decreased from 70% in wide rows to 30% in narrow rows. Mechanical treatment produced weed levels similar to those in narrow rows (27%). Mechanical treatment gave grain yields of 2.3 t ha−1, that are comparable with chemically treated plots (2.7 t ha−1). For chickpea, mechanical treatment combined with wide rows proved effective in fighting weeds at a similar level to chemical treatment. Moreover, the yield using mechanical treatment, of 1.6 t ha−1, was only slightly lower than the yield using chemical treatment (2.3 t ha−1). For field peas, mechanical and cropping weed control can limit herbicides, but they are unable to control weed infestation on their own.

Industrial orange waste as organic fertilizer in durum wheat

Nowadays agro-industrial waste induces increasing problems due to the high economic cost and heavy environmental impact of disposal. By contrast, its potential re-use as organic fertilizer could represent a sustainable approach to recycling nutrients and reintegrating organic matter into soil. Such recycling should be particularly beneficial in Mediterranean areas because there is a progressive loss of soil fertility. To assess the possible re-use of industrial citrus waste as organic fertilizer, a two-year research project was carried out to study the effects of dried orange waste on the growth and production of durum wheat (Triticum durum Desf.). Two dried orange waste doses of 4 and 8 kg/m2 were compared with conventional mineral fertilization, of 80 kg/ha2 of nitrogen, and with a control without fertilization in the first year. During the second year, the residual effects of the past year’s fertilization and two-year application of the orange waste doses and mineral fertilization on duration of biological cycle, grain yield, leaf area index, above-ground biomass and crop growth rate were studied. Our results show that organic fertilization gave similar wheat yields to the mineral fertilization, averaging at 3.63 t/ha. Organic fertilization promoted crop growth much more than mineral fertilization, by up to +400%. However, at the highest dose repeated organic fertilization induced a severe depressive effect on crop establishment. It indeed gave the lowest values for leaf area index of 0.6, biomass of 222 g/m2 dry weight and crop growth rate of 2.5 g m−2 d−1 at the heading stage, and a 50% decrease in wheat grain yield. In both years, the lowest dose of orange waste produced maximum agronomic efficiency. We conclude that an appropriate use of dried orange waste as fertilizer can partially solve environmental problems related to the citrus fruit processing industry, and represents a low cost organic matter source for Mediterranean soil with poor fertility.

Germination response of four pasture species to temperature, light, and post-harvest period

Abstract The purpose of this research was to explore the effect of temperature, light, and post-harvest period, and their interactions, on seed germination ecology of four common pasture species in the Mediterranean environment. Mature seeds of Diplotaxis erucoides, Hirschfeldia incana, Hyoseris scabra (Mediterranean distribution) and Sonchus oleraceus (cosmopolitan distribution) were subjected to seven constant temperatures (10–40°C, at intervals of 5°C) under continuous darkness, or a 12 h/12 h light/dark photoperiod at 30, 150 and 270 days after harvest (DAH). Cumulative germination and germination speed were determined. In all the tested species, except S. oleraceus, light significantly enhanced germination. S. oleraceus seeds maintained germination values over 90%, in a wide range of temperatures (10–35°C), in the dark as well as in light. Seeds of H. incana germinated well soon after seed dispersal. In D. erucoides and H. scabra, germination increased with storage period, while in S. oleraceus there was no effect of seed age. In all the species, moreover, no germination was recorded at 40°C. Temperature, light, and post- harvest requirement may be regarded as an adaptation strategy to ensure optimal conditions for seedling development and survival in Mediterranean species, while the species with a cosmopolitan distribution germinates under almost all tested conditions.

Agronomic Characterization of Some Spontaneous Genotypes of Milk Thistle (Silybum marianum L. Gaertn.) in Mediterranean Environment

ABSTRACT Spontaneous populations of Silybum marianum L. of three environments were evaluated for their biological and productive traits. Despite the different environmental conditions of the studied sites (hill and plane), there was a general uniformity in the main observed plant traits. Hilly environments produced a higher number of secondary flower heads compared with the plane site. Seeds in the secondary flower heads had a conspicuously lower weight (−56%) when compared to the primary ones. Plant height and height of the first branch insertion was positively related, directly or indirectly, to the seed yield. A first approach for the definition of an ideotype is proposed.

Germinative response of redroot pigweed (Amaranthus retroflexus L.) to environmental conditions: Is there a seasonal pattern?

Experiments on redroot pigweed (Amaranthus retroflexus L.) were conducted to investigate whether the germinative response to environmental conditions is affected by the time of seed set. Seeds were collected in the same field (Sicily, Southern Italy) in May, July and October; each lot was dry-stored from 15 to 400 days after harvest (DAH) and submitted to germination assays from 15 to 40°C, both in continuous darkness (D) and in alternate light/darkness regime (L/D). For the three lots, over 15 DAH, the response to temperature and light regime was strongly affected by harvesting time. Seeds set in May, negatively affected by L/D, showed a high germination capability (>80%) at 95 DAH from 25 to 40°C. Seeds set in July were favoured by L/D and required at least 170 DAH to reach 80% germination capability. Seeds set in October were also favoured by L/D and gave a good germination capability only at 300 and 400 DAH. These results prove that seed germination behaviour in redroot pigweed is not independent of the time of the year in which seeds are produced and is due to both the environmental conditions experienced by the mother plant during seed maturation and those experienced by seeds after seed set.