Repeated applications of phosphorus (P) fertilizers result in the buildup of P in soil (commonly known as legacy P), a large fraction of which is not immediately available for plant use. Long-term applications and accumulations of soil P is an inefficient use of dwindling P supplies and can result in nutrient runoff, often leading to eutrophication of water bodies. Although soil legacy P is problematic in some regards, it conversely may serve as a source of P for crop use and could potentially decrease dependence on external P fertilizer inputs. This paper reviews the (1) current knowledge on the occurrence and bioaccessibility of different chemical forms of P in soil, (2) legacy P transformations with mineral and organic fertilizer applications in relation to their potential bioaccessibility, and (3) approaches and associated challenges for accessing native soil P that could be used to harness soil legacy P for crop production. We highlight how the occurrence and potential bioaccessibility of different forms of soil inorganic and organic P vary depending on soil properties, such as soil pH and organic matter content. We also found that accumulation of inorganic legacy P forms changes more than organic P species with fertilizer applications and cessations. We also discuss progress and challenges with current approaches for accessing native soil P that could be used for accessing legacy P, including natural and genetically modified plant-based strategies, the use of P-solubilizing microorganisms, and immobilized organic P-hydrolyzing enzymes. It is foreseeable that accessing legacy P will require multidisciplinary approaches to address these limitations.

Capturing cell-to-cell signals in a three-dimensional (3D) environment is key to studying cellular functions. A major challenge in the current culturing methods is the lack of accurately capturing multicellular 3D environments. In this study, we established a framework for 3D bioprinting plant cells to study cell viability, cell division, and cell identity. We established long-term cell viability for bioprinted Arabidopsis and soybean cells. To analyze the generated large image datasets, we developed a high-throughput image analysis pipeline. Furthermore, we showed the cell cycle reentry of bioprinted cells for which the timing coincides with the induction of core cell cycle genes and regeneration-related genes, ultimately leading to microcallus formation. Last, the identity of bioprinted Arabidopsis root cells expressing endodermal markers was maintained for longer periods. The framework established here paves the way for a general use of 3D bioprinting for studying cellular reprogramming and cell cycle reentry toward tissue regeneration.

Conditions evaluated the influence of sub‐herbicidal applications of 2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine (simazine) on the crude protein content and yield of several forage cultivars. In the greenhouse significant increases in percent crude protein and, generally, decreases in both dry matter yield and percent cellulose occurred when ‘Kenwell’ and ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.), ‘Climax’ timothy (Phleum pratense L.), common perennial ryegrass (Lolium perenne L.), annual ryegrass (Lolium multiflorum Lam.), an allotetraploid ryegrass (Lolium sp.), and several Lolium‐Festuca synthetics were treated with simazine. Significant simazine × cultivar Interactions occurred. Tall fescue gave increased yields of crude protein without sacrificing yields of dry matter. Under field conditions reed canarygrass (Phalaris arundinacea L.), treated at five nitrogen (N) levels — 0, 56, 112, 224, and 448 kg/ha — was sprayed with simazine at rates of 0, 0.07, 0.14, 0.28, and 0.56 kg ai/ha on two dates. Three harvests were taken. Simazine and N effects were significant (P<0.01) with respect to dry matter yield. Increased levels of crude protein were evident as a result of simazine application in the first harvest and at the high N level in the second. Increased yields of crude protein were obtained at the 224 kg N/ha level as a result of simazine application compared to controls.

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