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European chestnut is the most important cash crop in the highlands of NE Portugal. However, limited data on cropping technique are available to help farmers make decisions. This work is motivated by the lack of data related to chestnut response to fertilizer application. It reports results from a field fertilization trial consisting of the application of a combination of lime (L), nitrogen (N), phosphorus (P), potassium (K), and boron (B), namely LNPKB, NPKB, -NPKB, N-PKB, NP-KB, and NPK-B. Seedlings of chestnut were planted in June 2013 and grown for four growing seasons. Plant height, trunk diameter, and pruning wood were assessed every year and used as indicators of tree crop growth. Elemental leaf analysis and other tools [SPAD-502 chlorophyll meter; Field Scout CM 1000 NDVI (normalized difference vegetation index) meter, and the OS-30p+ fluorometer] were used to assess plant nutritional stresses. In January 2017 soil samples were collected at three depths (0-5, 5-10, and 10-20 cm) to determine several soil fertility parameters. The nonapplication of K and B reduced the tree crop growth and pruning residues. Leaf analysis revealed leaf K and B concentrations respectively in the NP-KB and NPK-B treatments to be in the deficient range previously established for chestnut. SPAD readings and NDVI detected the reduced availability of N associated with the -NPKB treatment but not the reduced plant growth associated with NP-KB or NPK-B treatments. The dark adaptation protocols of F V /F M , F V /F 0 , and OJIP measurements performed with the OS-30p+ fluorometer failed to diagnose the nutrient stresses detected by leaf analysis or the reduction in plant growth.

In cultivated fields, patches of poorly developed vegetation often appear without a clear indication of what is affecting the growth of the plants. The purpose of this study was to investigate the causes behind these irregularities in the hop (Humulus lupulus L.) fields of NE Portugal which are greatly reducing crop yield and farmers' profits and to provide guidance to farmers as to appropriate remedial action. Patches of different levels of plant development were selected within hop fields and categorized according to plant vigour (weak, fair and good). Several soil properties were determined and related to the plant nutritional status and dry matter yield of different parts of the plant (hops, leaves, stems). Data was subjected to analysis of variance and principal component analysis. The results suggest that crop yield is reduced mostly due to poor soil aeration and excessive soil and tissue Mn and Fe levels. The plants from the plots of weaker vigour seem to be particularly affected by toxic levels of Mn and the plants from the plots of fair vigour by Fe levels. pH, texture (clay content), cation exchange capacity and organic carbon seem to be other soil properties with some degree of influence on plant performance. From these results, farmers are advised to increase soil aeration by implementing a drainage system and converting to a drip irrigation system, in addition to increasing soil pH by liming to reduce Mn toxicity.

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