Nitrogen (N) management remains a global challenge for the sustainability of diversified farming systems. Field crops are often over-supplied with nitrogen by farmers aiming to high productivity. Although the increase of nitrogen rates leads in many instances to high yields, degree of effectiveness for nitrogen use remains low. Urease and nitrification inhibitors are technologies which have been present in the fertilizers market at least 50 years. Inhibitors exploitation ensures long-term nitrogen release and improved N-uptake by plants and N-storage in seeds and silage. Avail of inhibitors, such as the decline of nitrogen leaching in form of NO3−, reduction of emissions in NH3 form, and rise of yield, are some of the desirable attributes that are derived from their integration in fertilization schedules. This review reports the evaluation of applied nitrogen, with inhibitors, and field crops based on nitrogen indices. The examined N-indicators include Nitrogen use efficiency (NUE), Nitrogen Utilization Efficiency (NUtE,) Nitrogen Agronomic Efficiency (NAE), Nitrogen Harvest Index (NHI), and N uptake. This review gathered all, to the best of our knowledge, available data regarding the utilization of nitrification and urease inhibitors under an exclusively agronomic perspective. Either dual or single use of nitrification and urease inhibitors has been reported to significantly increase yield components and promote nitrogen uptake. To conclude, the assessment of N-related indices is vital to promoting sustainability in diversified farming systems, while the integration of inhibitors in national N fertilizations schemes may contribute to system profitability through enhancement of N-supply to crops.

The cultivation of cotton and in particular the quality characteristics of the fiber are mainly influenced by the growing conditions, the cultivation techniques as well as the climatic changes of the environment. The current study aimed to quantify the impact of environment, season, and their interactions on cotton fiber quality of different areas where cotton is grown in Greece. A large-scale database was created, consisting of more than 20,000 fiber samples from cotton fields of the four major cotton-producing regions of Greece (Thrace, Macedonia, Central Greece, and Thessaly) during 2016–2020, in order to evaluate thirteen fiber quality traits that were divided into four groups (fiber maturity, fiber length, color, and trash traits). The results of this work demonstrated that the effect of the environment and the interaction of the environment with year (season), were the important source of variance for almost all the qualitative characteristics studied. Regional climatic characteristics such as temperature, humidity and rainfall also significantly affected to a greater or lesser extent all quality characteristics. In conclusion, the different cultivation regions, in the broader sense of an environment that incorporates both climatic and management parameters, show stability in terms of the studied groups of quality parameters. This stability is independent of the high or low performance of the group features.

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Greenhouse tomato plants were grown hydroponically during the period of lower temperatures of winter (LT) versus the period of higher temperatures of summer (HT). In these plants, the effect of season on fruit load was dramatic. In order to study the alterations season introduces to the developmental allocation of nutrients within the various organs, concentrations of total nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined during each season at weekly intervals in the dry mass of leaves and roots and in the extract of upper, middle, and lower parts of the stem. The level of N/ P ratio was always higher in the leaves than in the roots, and these differences were more intense during HT. The short-term changes of ratio in the leaves during HT and LT were positively related with the changes in temperature (r = 0.59 and 0.51 for HT and LT, respectively). In contrast, such correlations in the root were negative (r = −0.54 and r = −0.33 for HT and LT, respectively). The increase of temperature increased P uptake but not its translocation to upper plant parts. HT affected the translocation of N, K, Mg, and Ca more and their uptake less. Fruit load differentially affected the concentration of nutrients. In contrast to total N and K, Ca concentration in plant parts presented a positive relation with the increase of fruit load. Calcium and total N concentration (as opposed to P and micronutrient concentrations) were always higher in the leaves than in the roots. Under HT conditions, P was accumulated in roots in combination with high concentrations of Fe, Zn, and Mn. On the other hand, K and N were accumulated 505 Downloaded by [UQ Library] at 00:28 02 November 2014 506 M. K. Darawsheh et al.in the roots during the period of low temperature in winter. Calcium and K compared with other nutrients presented a pronounced tendency to be transported toward the top of the stem during HT, and their extractable concentration in the upper part of stem presented a significant increase during summer. Extractable K concentration was two to nine times higher than that of the other macronutrients. Our data suggest that the extractable concentration of nutrients of the stem is a good index for the diagnosis of the mineral nutritional status of the plant.

Decrease of width between cotton (Gossypium hirsutum L.) row spacing has been suggested as an agronomic practice that may increase the yield and reduce the cost production. Altering agronomic practices as row spacing system as well as irrigation regime can affect cotton growth parameters, yield components, and physical fiber properties. The object of this study is the assessment of interaction between row spacing cropping systems and irrigation regime and their effects on yield components. Yield, biomass, harvest index, seed index, seed weight, bolls number, individual boll weight, the proportion of lint and seed were studied in three row spacing systems [conventional row (CR), narrow row (NR) and ultra-narrow row (UNR)] under typical and limited irrigation regime, during two growing seasons. The decrease of row spacing had different effect on yield components under the typical and limited irrigation regime e.g. the differences between systems of row spacing on bolls number were more evident under the limited irrigation than the typical one, and the opposite was true for the lint proportion. Decreased row spacing had positive effects on yield, biomass, bolls number per land area and lint proportion in two irrigation systems. However, had negative impact on individual boll weight, seed weight, seed index, harvest index and seed proportion. Interaction of row spacing and irrigation regime was significant for seed index. High differences were more significant between UNR and CR and less between NR and CR. UNR system appeared to be viable alternative to traditional row system for cotton production.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********