Best Papers Introduction

I am pleased to announce three articles published in Horticulture in 2020 which were considered eligible for the Best Paper Award 2022 by the Editorial Board among the many excellent papers from that year. They are two articles and one review, representing publications which have generated significant interest in the horticultural sciences community.

These papers are:

“Salinity-Induced Physiological Responses of Three Putative Salt Tolerant Citrus Rootstocks”, 2020, Mahmoud et al.;

“Quality, Yield, and Biomass Efficacy of Several Hydroponic Lettuce (Lactuca sativa L.) Cultivars in Response to High Pressure Sodium Lights or Light Emitting Diodes for Greenhouse Supplemental Lighting”, 2020, Hernandez et al.;

“The Potential of Introduction of Asian Vegetables in Europe”, 2020, Hong and Gruda.

Mahmoud et al. have published an original study on the physiological responses of Citrus rootstocks following salinity treatments [1]. They evaluated the physiological responses of three putatively salt-tolerant Citrus rootstocks (HS1, HS17, and HC15) in comparison to others: the salt-tolerant Cleopatra mandarin, as positive control, the moderately salt-tolerant Volkamer and the salt-sensitive Carrizo, as negative control. Four-month-old seedlings of the six rootstocks were irrigated with increasing concentrations of NaCl (60, 80, and 100 mM solution) and subsequently analyzed. Only Carrizo, as expected, showed salt damage when irrigated with 60 mM NaCl and did not survive at 100 mM NaCl; the same salt concentration caused consistent foliar damage to all other seedlings, with the exception of HS15 and Cleopatra, which showed similar low damage. Transpiration rate, net CO₂ assimilation and stomatal conductance decreased in response to increasing NaCl level in all rootstocks, while HS15 and Cleopatra had little damage to the cellular membrane, and together with HS17 had the best performance regarding the presence of malondialdehyde, proline and phenolic compounds in the leaves. Naturally, the Na+ and Cl^- presence increased for all rootstocks by raising the salt concentration in the irrigation water, being generally higher in leaves; HS1, HS17, and HC15 did not show significant differences in comparison to Cleopatra, with the exception of Cl^- in roots. In summary, two of the tested rootstocks, HC15 and HS17, are capable of withstanding a 100 mM salt stress, a feature apparently linked to low production of malondialdehyde and to improved accumulation of proline (HS17) or phenolic compounds and proline (HC15). Therefore, the two rootstocks proved to be suitable for replacing the Cleopatra mandarin which is the major commercially important rootstock in Florida.

Hernandez et al. have published an interesting and challenging research article [2] about hydroponic greenhouse lettuce cultivar selection with an optimal daily light amount by means of high-pressure sodium (HPS) or light-emitting diodes (LED) in Ithaca, NY (42° N latitude). Light sources were controlled with an algorithm, Light and Shade System Implementation (LASSI), in order to have a constant average daily light (17 mol·m⁻²·d⁻¹) during the growing cycles, whereas the lettuce yield divided by the electricity consumption provided the electrical efficiency (fresh weight per kWh). The authors demonstrated that both types of additional lighting had a similar impact on lettuce yield and morphology, despite the fact that in some of the six crop cycles, the HPS lamps caused more tip burn and bolting during phase 1 (between January and May 2018), and larger plants than LED in phase 2 (between June and October 2018). The conclusion was that the effects of additional lighting are overestimated by some growers, and that in order to achieve electricity savings in lettuce cultivation, several factors need to be considered, starting with the choice of lamps/light output, light distribution and control of the switch-on time. However, a fundamental result is the indication of the edible mass/kWh, which is 2.5 to 4 times higher in favor of LED lighting in comparison to HPS lamps. This suggests that the choice of LEDs is advantageous despite the higher cost of lamps.

Hong and Gruda have published an extensive review [3] on the potential of several Asian vegetables with high potential for introduction into the European market, reporting a list of species categorized under six groups: (i) sprout vegetables, (ii) tree vegetables, (iii) leaf and stem vegetables, (iv) fruit, pod and seed vegetables, (v) root vegetables, and (vi) mushrooms. In addition, the authors indicated the respective culinary uses of the different organisms. Moreover, four Asian vegetables were recommended and accurately described in terms of their properties and methods of cultivation: (1) Korean ginseng sprouts (Panax ginseng Meyer), (2) Korean cabbage (Ssamchoo—Brassica lee ssp. Namai cv. Ssamchoo and Red Ssamchoo—Brassica koreana Lee var. Redleaf), (3) Coastal hog fennel—Peucedanum japonicum and (4) Japanese (Chinese or Korean) angelica tree—Aralia elata (Miq.) Seem. All of these vegetables are beneficial to health (or expected to be), are easy to grow, can be used to decorate dishes and are vegetables with unique taste, such that they suggest a demand for expansion in Europe. The introduction of these Asian vegetables onto the European market will contribute to an increase in the diversity of products and consumer choice, as well as new economic opportunities for European farmers. In conclusion, this review represents a precious indication, not only for agricultural producers, but above all for researchers, whose task it is to confirm review content relating to market research, studies on cultivation in different areas of Europe, and climate and ecological assessments.