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Light-harvesting and intramolecular energy funneling are fundamental processes in natural photosynthesis. A comprehensive knowledge of the main structural, dynamic, and optical properties that regu...

Both nitrogen and calcium fertilization management are vital for crops, where an imbalance of these elements can cause both physiological and yield problems. It has been proposed that nitrogen absorption, particularly ammonium, is in part dependent on calcium supply. Moreover, the balance between these two nutrients could be a key indicator of plant growth in some species. Tomato, one of the most cultivated crops worldwide, can also be widely affected by nutritional imbalance. Using large amounts of N fertilizers could lead to an imbalance with other nutrients and, thus, detrimental effects in terms of plant development and yield. Here we show that ammonium excess has a negative impact on plant development and results in calcium deficiency. Moreover, a deficit in calcium nutrition not only affects calcium concentration but also leads to a restriction in N uptake and reduced N concentration in the plant. These effects were evident at the seedling stage and also during flowering/fruit set. Using PCA analysis, we integrated both phenotypic and nutritional imbalances in seedlings and grown plants. Interestingly, the Ca/N ratio appears to be a key indicator to monitor appropriate N and calcium nutrition and more importantly the balance between both. Maintaining this balance could be an essential element for tomato crop production. Made available in DSpace on 2021-07-21T16:01:58Z (GMT). No. of bitstreams: 1 Ammonium-Excess-Leads-to-Ca-Restrictions-2021.pdf: 1980106 bytes, checksum: c6f77a850c31e9c1f3389cce0b48c0b7 (MD5) Previous issue date: 2021

In this issue of Chem Catalysis, de Ruiter and co-workers report a highly efficient and selective method for isomerization of a wide variety of terminal alkenes, employing the well-defined anionic complex [(PCNHCP)Fe(H)N2][Na]. This work also includes important insights about the structure and reactivity of the iron intermediates involved in the catalytic cycle.

Calcium (Ca) is often supplied to crop species to prevent the occurrence of Ca–related disorders. Mechanisms of Ca absorption and transport are not fully understood and the effectiveness of root and/or foliar Ca fertilization may be variable. To characterize the rate of Ca absorption and transport, trials were developed with chili pepper and sweet cherry plants, using 45CaCl2 as a tracer. The Ca treatments supplied were: (1) No 45Ca (control); (2) 45Ca soil application; (3) 45Ca supply to basal leaves, and (4) 45Ca application to apical leaves. After two months, plants were harvested for biomass and Ca content determination. The recovery of 45Ca in different plant parts was measured with a liquid scintillation counter and leaf traits were observed by scanning electronic microscopy. In general, the highest 45Ca concentrations were recovered in treated organs, while root applications led to highest 45Ca translocation rates, which varied between chili pepper and cherry plants. For chili pepper, 45Ca applied to the soil was detected mainly in roots (44 %) followed by leaves (36.6 %) stems (17.4 %) and fruits (2 %). In sweet cherry trees, soil–applied 45Ca was principally recovered in roots (45.3 %), shoots (28.5 %), leaves (14.3 %) and trunks (11.9 %). The results provide evidence of increased absorption of root–applied Ca, as well as different degrees of Ca mobility between species. Foliar application led to major Ca increases in treated leaves, with Ca transported to other plant organs after apical leaf Ca supply chiefly in cherry trees.

Homoleptic iron-alkyl complexes have been implicated as key intermediates in iron-catalyzed cross-coupling with simple iron salts. Tetraalkyliron(III) ferrate species have been shown to be accessible with either methyl or benzyl ligands, where the former complex is S = 3/2 and distorted square planar while the latter is a S = 5/2 distorted tetrahedral species. In the current study, a new tetraalkyliron(III) complex is synthesized containing modified methylene substituents that incorporate large trimethylsilyl (TMS) groups to further probe steric and electronic ligand effects in tetraalkyliron(III) complexes by increasing the electron-donating ability of the ligand while retaining steric bulk. Detailed structural and DFT studies provide insight into electronic structure and bonding of the four-coordinate trimethylsilylmethyl iron(III) complex compared to the previously reported analogs containing methyl and benzyl ligands.