BACKGROUND: There is growing interest among consumers in baby leaf vegetables, mostly requested for mixed salads, both as fresh market products and ready-to-use vegetables. Fertilisation is one of the most practical and effective ways of controlling and improving the yield and nutritional quality of crops for human consumption. The optimal fertiliser concentration for baby leaf vegetables depends on the environmental conditions. The aim of the present work was to determine the effects of nutrient solution concentration (2, 18, 34, 50 or 66 mequiv L −1 ) during two consecutive growing seasons (spring and summer) on the yield and leaf quality of Lactuca sativa L. var. acephala grown in a floating system.

The effect of three different nitrogen (N) supply forms differing in their ammonium-to-nitrate (NH(4):NO(3)) ratio (100% NH(4), 50% NH(4) + 50% NO(3), 100% NO(3)) under three different levels of daily photosynthetic active radiation (PAR) (low, 5.0; medium, 6.8; high, 9.0 mol m(-2) day(-1)) on a range of desirable health-promoting phytochemicals in Brassica rapa subsp. nipposinica var. chinoleifera and Brassica juncea was determined. The 100% NH(4) supply under medium PAR levels led to the highest concentration of glucosinolates based on a low nitrogen/sulfur ratio as well as high levels of carotenoids in the leaves of both Brassica species. However, the 100% NH(4) supply under low and medium PAR levels resulted in low concentrations of flavonoids based on high N concentration in the leaves. Thus, the data provided here have strong implications for crop management strategies aimed at optimizing both the concentration and composition of a range of phytochemicals.

Accurate and nondestructive methods to determine individual leaf areas of plants are a useful tool in physiological and agronomic research. Determining the individual leaf area (LA) of small fruit like raspberry (Rubus idaeus L.), redcurrant (Ribes rubrum L.), blackberry (Rubus fruticosus L.), gooseberry (Ribes grossularia L.), and highbush blueberry (Vaccinium corymbosum L.) involves measurements of leaf parameters such as length (L) and width (W) or some combinations of these parameters. A 2-year investigation was carried out during 2006 (on seven raspberry, seven redcurrant, six blackberry, five gooseberry, and two highbush blueberry cultivars) and 2007 (on one cultivar per species) under open field conditions to test whether a model could be developed to estimate LA of small fruits across cultivars. Regression analysis of LA versus L and W revealed several models that could be used for estimating the area of individual small fruit leaves. A linear model having LW as the independent variable provided the most accurate estimate (highest R 2, smallest mean square error, and the smallest predicted residual error sum of squares) of LA in all small fruit berries. Validation of the model having LW of leaves measured in the 2007 experiment coming from other cultivars of small fruit berries showed that the correlation between calculated and measured small fruit berries LAs was very high. Therefore, these models can estimate accurately and in large quantities the LA of small fruit plants in many experimental comparisons without the use of any expensive instruments.

A greenhouse experiment was carried out to evaluate the effect of Salsola soda used as a desalinating companion plant on growth, yield, mineral composition, and fruit quality of pepper (Capsicum annuum) grown under moderate (electrical conductivity (EC) = 4.0 dS m -1 ) and high salt concentration (EC = 7.8 dS m -1 ). The presence of S. soda decreased the EC of the medium by 45% and increased the total yield, marketable yield, and total biomass of pepper by 26%, 32%, and 22% respectively, in comparison with those grown without S. soda. The increase in marketable yield under moderate salt stress with S. soda was the result of a higher fruit mean weight and not the number of fruit. S. soda did not prevent suppression of growth and yield on pepper under severe salt conditions. Increasing the nutrient solution salinity improved fruit quality by increasing dry matter (DM) and total soluble solid (TSS) content. Under moderate saline conditions, the concentrations of sodium (Na) and chloride (Cl -) in pepper leaves were lower when S. soda was used as a companion plant, whereas no difference was recorded on Na and Cl concentrations of leaves at 7.8 dS m calcium (Ca) was observed in pepper leaves in the presence of the companion plant at 4.0 dS m -1 . The results demonstrate that using S. soda as a companion plant under moderate saline concentrations would be an attractive strategy in limiting yield reduction.

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