Isosmotic Macrocation Variation Modulates Mineral Efficiency, Morpho-Physiological Traits, and Functional Properties in Hydroponically Grown Lettuce Varieties (Lactuca sativa L.)

The management of mineral elements in agriculture is important for their nutritional role for plants and dietary value for humans, sparking interest in strategies that can increase mineral use efficiency and accumulation in plant food. In this work, we evaluated the effects of the isosmotic variations of the concentration on three macrocations (K, Ca, and Mg) in lettuce (Lactuca sativa L.). Our aim was to improve the nutritional components of this valuable dietary source of minerals. Using a full factorial design, we analyzed mineral utilization efficiency (UtE), leaf morphology, gas exchange parameters, phenolic profiles (through ultra-high performance liquid chromatography coupled to a quadrupole-time-of-flight (UHPLC-QTOF) mass spectrometry), and enzymatic activities in two phytochemically diverse butterhead lettuce varieties (red or green). Plants were fed in hydroponics with three nutrient solutions (NSs) with different ratios of K, Ca, and Mg. The variation of these minerals in the edible product was associated with alterations of the morphology and physiology of the leaves, and of the quality and functional properties of lettuce, with a trade-off between total accumulation and mineral UtE. Moreover, in non-limiting conditions of nutrient availability, significant mineral interactions were also present. The flexibility of the plant response to the different ratios of macrocations, and the observed large intraspecific variation, were adequate to provide mineral-specific phytochemical profiles to the edible product. Specifically, the full-red lettuce provided more interesting results in regard to the compositional and functional attributes of the leaves.

Welfare and product quality: the need to be humane

In this paper it will be argued that the relationships between welfare and product quality are not commonplace because processes within the animal intervene between substrate and product which reduce farming practices to a common level that is subordinate to the animal's metabolism. Nevertheless there are four ways in which compromised welfare can be linked to product quality: (1) product quality which is influenced by acute stress; (2) ante-mortem trauma occurring in parts of the animal which are edible; (3) disease states which leave lesions or taints in the edible product; and (4) product quality which is dependent on the long-term cumulative effects of exercise, lack of exercise or poor husbandry conditions.From this classification and the examples to be given in the paper it will become clear that some practices which compromise welfare can lead to poor product quality but there is little evidence to suggest that improved welfare practices benefit product quality. Nevertheless welfare improved products could be of better quality simply because more effort and attention is put into their production. If the same care and expenditure were to be put into systems where welfare was not the main goal, would product quality be any different?The conclusions that will be drawn from this paper are that: (i) practices which compromise welfare can lead to poor product quality, but there is little evidence that improved welfare benefits product quality; and (ii) modern labelling is suggestive instead of being explicit and as such it does not lend itself to promoting welfare improvements in a cognizant manner.