Lettuce crops

A lettuce crop that grows rapidly owing to excessive fertiliser often lacks taste and may be susceptible to disease (may indicate too much growth). 

Patricio FRA, Sinigaglia C, Barros BC, Freitas SS, Tessarioli Neto J, Cantarella H, Ghini R (2006) Solarization and fungicides for the control of drop, bottom rot and weeds in lettuce. Crop Prot 25 31-38. doi 10.1016/j.cropro.2005.03.002... 

Ngouajio, M., McGiffen, M.E. and Hutchinson, C.M. 2003. Effect of cover crop and management system on weed populations in lettuce. Crop Protection 22 57-64. 

Plant, W. (1952). The molybdenum content of some brassicae and lettuce crops in acid soils. Trans. Int. Soc. Soil Sci. Comm. II-IV 2 176-7. Reisenauer, H. M. (1956). Molybdenum content of alfalfa in relation to... 

Water-Culture Techniques. These hydroponic methods, which are frequendy used to cultivate plants that quickly attain maturity, involve roots constantly being suspended in a nutrient solution. Water-culture hydroponic techniques are often utilized to grow lettuce crops. For the raft culture technique, growers place plants on platforms drilled with holes to pull roots through so roots can be submerged in pools of nutrient solution on which the platforms float. In the dynamic root floating technique, roots closest to the plant are kept dry so they can supply oxygen to the plant. The lower roots are constantly exposed to nutrient solutions and absorb those minerals and elements to nourish the plant. 

Another groundwater contaminant that can be removed by reduction reactions is perchlorate. Ammonium perchlorate is a solid rocket fuel, and wastes from its manufacturing have contaminated some irrigation and drinking water sources, among them the lower Colorado River in the American Southwest. Elevated perchlorate levels have been linked to human health effects, and because perchlorate has been found in vegetable crops such as lettuce, there is concern that this contamination could have serious consequences. 

Seeds of lettuce and other species have frequently been used to bioassay for the allelopathic activity of plant exudates (17.18.19). As with the use of cell suspensions, there are certain advantages and disadvantages to this methodology. The experimental simplicity, small amounts of material required and short time frame are certainly attractive qualities. However, species used in such bioassays quite often do not represent the actual target species under consideration. This is especially true when terrestrial crop species are substituted for weeds of aquatic systems. Nevertheless, information obtained from such experiments are often valuable when used in conjunction with results of other assays. 

Wolnik KA, Fricke FL, Capar SG, et al. 1983a. Elements in major raw agricultural crops in the United States. 1. Cadmium and lead in lettuce, peanuts, potatoes, soybeans, sweet com, and wheat. J Agric Food Chem 31 1240-1244. 

The lettuce example demonstrated the importance of balanced growth in the growing stages of the crop in order to acquire mature quality properties. We had to work out the balance and tried to do this using the optimal proportion between two major life processes of mass growth and differentiation in form and substances . 

Fig. 5.1 Comparison of crop development of leaf lettuce (Lammerts van Bueren and Hospers 1991). Dates are presented as numbers ( 27-2 means 27 February).

Coniothyrium minitans Contans White mold, leafdrop Cole crops, beans, tomatoes, carrots, lettuce Fungicide... 

Schneider and Gerlach in tomato (Lycopersicon esculentum L.), S. minor on lettuce (Lactuca sativa L.) and weeds, improving also crop yield and quality (Panattoni et al. 2004 Cascone et al. 2005 Castronuovo et al. 2005). 

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