Sugar Beet Cultivation in the Tropics and Subtropics: Challenges and Opportunities

Sugar beet, an important sugar crop, is particularly cultivated in humid regions to produce beet sugar, fulfilling about 25% of the world’s sugar requirement, supplementing cane sugar. However, sugar beet is not well adopted in the farming system of the tropics and subtropics, which is largely due to the historically well-established production technology of sugarcane and the lower awareness among local growers of sugar beet cultivation. Thus, the poor understanding of pest and disease management and the lack of processing units for sugar beet partially hinder farmers in the large-scale adaptation of sugar beet in the tropics and subtropics. Recent climatic developments have drawn attention to sugar beet cultivation in those regions, considering the low water demand and about half the growing duration (5–6 months) in contrast to sugarcane, sparing agricultural land for an extra crop. Nevertheless, a considerable knowledge gap exists for sugar beet when closely compared to sugarcane in tropical and subtropical growth conditions. Here, we examined the leverage of existing published articles regarding the significance and potential of sugar beet production in the tropics and subtropics, covering its pros and cons in comparison to sugarcane. The challenges for sugar beet production have also been identified, and possible mitigation strategies are suggested. Our assessment reveals that sugar beet can be a promising sugar crop in tropical and subtropical regions, considering the lower water requirements and higher salt resistance

Effect of boron deficiency on the photosynthetic performance of sugar beet cultivars with contrasting boron efficiencies

Boron (B) deficiency severely affects the quality of sugar beet production, and the employment of nutrient-efficient varieties for cultivation is a crucial way to solve environmental and resource-based problems. However, the aspect of leaf photosynthetic performance among B-efficient sugar beet cultivars remains uncertain. The B deficient and B-sufficient treatments were conducted in the experiment using KWS1197 (B-efficient) and KWS0143 (B-inefficient) sugar beet cultivars as study materials. The objective of the present study was to determine the impacts of B deficiency on leaf phenotype, photosynthetic capacity, chloroplast structure, and photochemical efficiency of the contrasting B-efficiency sugar beet cultivars. The results indicated that the growth of sugar beet leaves were dramatically restricted, the net photosynthetic rate was significantly decreased, and the energy flux, quantum yield, and flux ratio of PSII reaction centers were adversely affected under B deficiency. Compared to the KWS0143 cultivar, the average leaf area ratio of the KWS1197 cultivar experienced less impact, and its leaf mass ratio (LMR) increased by 26.82% under B deficiency, whereas for the KWS0143 cultivar, the increase was only 2.50%. Meanwhile, the light energy capture and utilization capacity of PSII reaction centers and the proportion of absorbed light energy used for electron transfer were higher by 3.42% under B deficiency; KWS1197 cultivar managed to alleviate the photo-oxidative damage, which results from excessive absorbed energy (ABS/RC), by increasing the dissipated energy (DIo/RC). Therefore, in response to B deprivation, the KWS1197 cultivar demonstrated greater adaptability in terms of morphological indices and photosynthetic functions, which not only explains the improved performance but also renders the measured parameters as the key features for varietal selection, providing a theoretical basis for the utilization of efficient sugar beet cultivars in future

Biochar-mediated control of metabolites and other physiological responses in water-stressed Leptocohloa fusca

We investigated biochar-induced drought tolerance in Leptocohloa fusca (Kallar grass) by exploring the plant defense system at physiological level. L. fusca plants were exposed to drought stress (100%, 70%, and 30% field capacity), and biochar (BC), as an organic soil amendment was applied in two concentrations (15 and 30 mg kg−1 soil) to induce drought tolerance. Our results demonstrated that drought restricted the growth of L. fusca by inhibiting shoot and root (fresh and dry) weight, total chlorophyll content and photosynthetic rate. Under drought stress, the uptake of essential nutrients was also limited due to lower water supply, which ultimately affected metabolites including amino and organic acids, and soluble sugars. In addition, drought stress induced oxidative stress, which is evidenced by the higher production of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), superoxide ion (O2−), hydroxyl ion (OH−), and malondialdehyde (MDA). The current study revealed that stress-induced oxidative injury is not a linear path, since the excessive production of lipid peroxidation led to the accumulation of methylglyoxal (MG), a member of reactive carbonyl species (RCS), which ultimately caused cell injury. As a consequence of oxidative-stress induction, the ascorbate–glutathione (AsA–GSH) pathway, followed by a series of reactions, was activated by the plants to reduce ROS-induced oxidative damage. Furthermore, biochar considerably improved plant growth and development by mediating metabolites and soil physio-chemical status

Synthesis, Structures, and Norbornene Polymerization Behavior of <i>o</i>‑Aryloxide-Substituted NHC-Ligated σ, π‑Cycloalkenyl Palladium Complexes

Treatment of the pro-ligand (2-OH-3,5-^<i>t</i>Bu₂C₆H₂)­(Mes)­(C₃H₃N₂)⁺Br^– (<b>2a</b>) with di­[μ-chloro-2η²,5η¹-(6-methoxy-<i>endo</i>-bicyclo­[2.2.1]-hept-2-enyl)­palladium­(II)] (<b>1a)</b> and K₂CO₃ in dioxane, or reaction of the pro-ligand <b>2a</b> subsequently with ^<i>n</i>BuLi and <b>1a</b> in THF afforded the <i>o</i>-aryloxide-substituted NHC-ligated σ, π-cycloalkenyl palladium complex <b>3</b>. Similarly, treatment of the pro-ligands (2-OH-3,5-^<i>t</i>Bu₂C₆H₂)­(R)­(C₃H₃N₂)⁺Br^– [R = Mes (<b>2a</b>), Me (<b>2b</b>), ^<i>i</i>Pr (<b>2c</b>), Ph (<b>2d</b>)] with bis­[μ-chloro-1η²,5η¹-(6-ethoxy-<i>exo</i>-5,6-dihydrodicyclopentadienyl)­palladium­(II)] (<b>1b</b>) and K₂CO₃ in dioxane afforded the desired products <b>4</b>–<b>9</b>. All these complexes were fully characterized by ¹H and ¹³C NMR, high-resolution mass spectrometry (HRMS), and elemental analysis. Single-crystal X-ray diffraction analysis results further confirmed the molecular structures of <b>3</b>–<b>6</b>. With methylaluminoxane (MAO) as cocatalyst, these complexes showed excellent catalytic activities up to 10⁷ g of PNB (mol of Pd) ^–1 h^–1 in the addition polymerization of norbornene

Synthesis, Structures, and Norbornene Polymerization Behavior of N‑Heterocyclic Carbene-Sulfonate-Ligated Palladacycles

A series of new N-heterocyclic carbene-sulfonate (NHC-sulfonate) ligands <b>5a</b>–<b>e</b> were synthesized. Treatment of the NHC-sulfonate ligands with Ag₂O and palladacycles {[Pd­(OAc)­(8-Me-quin-H)]₂ or [Pd­(dmba)­(μ-Cl)]₂ (dmba = Me₂NCH₂C₆H₅)} yielded the desired C­(sp³),N-chelated and C­(sp²),N-chelated NHC-sulfonate palladacycles <b>6a</b>–<b>e</b> and <b>7a</b>–<b>e</b> in high yields. All these complexes were fully characterized by ¹H and ¹³C NMR, high-resolution mass spectrometry, and elemental analysis. The molecular structures of compounds <b>5a</b>, <b>6d</b>, <b>6e</b>, and <b>7e</b> were determined by single-crystal X-ray diffraction analysis. In the presence of MAO, the C­(sp³),N-chelated NHC-sulfonate palladacycles <b>6a</b>–<b>e</b> showed excellent catalytic activities [10⁷ g of polynorbornene (PNB) (mol of Pd)⁻¹ h^–1], while the C­(sp²),N-chelated palladacycles <b>7a</b>–<b>e</b> showed moderate catalytic activities [10⁶ g of PNB (mol of Pd)⁻¹ h^–1] in the vinyl polymerization of norbornene. The C­(sp²),N-chelated palladacycles <b>7a</b>–<b>e</b> showed high thermal stability and reached the highest activities at high temperature (100 °C)

Boosting the efficiency of quantum dot–sensitized solar cells over 15% through light‐harvesting enhancement

Abstract How to improve the capacity of light‐harvesting is still an important point and essential strategy for the assembling of high‐efficiency quantum dot–sensitized solar cells (QDSCs). A believable approach is to implant new light absorption materials into QDSCs to stimulate the charge transfer. Herein, the few‐layer black phosphorus quantum dots (BPQDs) are synthesized by electrochemical intercalation technology using bulk BP as source. Then the obtained BPQDs are deposited onto the surface of Zn–Cu–In–S–Se (ZCISSe) QD‐sensitized TiO2 substrate to serve as another light‐harvesting material for the first time. The experimental results have shown that BPQDs can not only increase the absorption intensity by photoanode but also reduce unnecessary charge recombination processes at the interface of photoanode/electrolyte. Through optimizing the size and deposition process of BPQDs, the champion power conversion efficiency of ZCISSe QDSCs is increased to 15.66% (26.88 mA/cm2, Voc = 0.816 V, fill factor [FF] = 0.714) when compared with the original value of 14.11% (Jsc = 25.41 mA/cm2, Voc = 0.779 V, FF = 0.713)

Synthesis, Structures, and Norbornene Polymerization Behavior of Palladium Complexes Bearing Tridentate <i>o</i>‑Aryloxide-N-heterocyclic Carbene Ligands

A series of new pincer-type tridentate <i>o</i>-aryloxide-N-heterocyclic carbene ligands <b>2a</b>–<b>d</b> were synthesized. Treatment of the proligands with Ag₂O and (COD)­PdCl₂ afforded the desired <i>o</i>-aryloxide-NHC tridentate palladium complexes <b>3a</b>–<b>d</b> in high yields (NHC = N-heterocyclic carbene). In comparison with the above tridentate complexes, bidentate bis­(aryloxide-NHC) palladium complex <b>3e</b> was also synthesized. All of these complexes were fully characterized by ¹H and ¹³C NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. The molecular structures of <b>3a</b>,<b>b</b>,<b>d</b>,<b>e</b> were determined by single-crystal X-ray diffraction analysis. On activation with either methylaluminoxane (MAO) or diethylaluminum chloride (Et₂AlCl), all palladium complexes exhibited excellent activities of up to 5.99 × 10⁷ g of PNB (mol of Pd)⁻¹ h^–1 toward norbornene addition polymerization, and the monomer conversion is up to 99.9%. Notably, the tridentate palladium complexes show better activities than the corresponding bidentate bis­(aryloxide-NHC) palladium complexes in the presence of MAO. The resulting polymers were soluble in CHCl₃ when the reactions were conducted in the presence of Et₂AlCl and were characterized by gel permeation chromatography (GPC)

Synthesis, Structures, and Norbornene ROMP Behavior of <i>o</i>-Aryloxide-N-Heterocyclic Carbene <i>p</i>-Cymene Ruthenium Complexes

Treatment of the <i>o</i>-hydroxyaryl imidazolium proligands (2-OH-3,5-^<i>t</i>Bu₂C₆H₂)­(R)­(C₃H₃N₂)⁺Br^– (R = ^<i>i</i>Pr (<b>1a</b>), ^<i>t</i>Bu (<b>1b</b>), Ph (<b>1c</b>), Mes (<b>1d</b>)) with 3 equiv of Ag₂O afforded the corresponding silver complexes <b>2a</b>–<b>d</b>. The subsequent metal-exchange reactions with [(<i>p</i>-cymene)­RuCl₂]₂ at room temperature yielded the desired <i>o</i>-aryloxide-N-heterocyclic carbene <i>p</i>-cymene ruthenium complexes <b>3a</b>–<b>d</b> in nearly quantitative yields. All the complexes were characterized by ¹H and ¹³C NMR, high-resolution mass spectrometry (HRMS), and elemental analysis. The molecular structure of complex <b>3b</b> was determined by single-crystal X-ray diffraction analysis. The ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with <b>3a</b>–<b>d</b> was studied. Among them, complex <b>3d</b> showed high activity and efficiency toward ROMP of NBE at 85 °C without the need for any cocatalyst, and polymers with very high molecular weight (>10⁶) and narrow molecular weight distributions were obtained. This complex can also catalyze the alternating copolymerization of NBE and cyclooctene (COE)

Synthesis, Structures, and Norbornene Polymerization Behavior of Palladium Complexes Bearing Tridentate <i>o</i>‑Aryloxide-N-heterocyclic Carbene Ligands

A series of new pincer-type tridentate <i>o</i>-aryloxide-N-heterocyclic carbene ligands <b>2a</b>–<b>d</b> were synthesized. Treatment of the proligands with Ag₂O and (COD)­PdCl₂ afforded the desired <i>o</i>-aryloxide-NHC tridentate palladium complexes <b>3a</b>–<b>d</b> in high yields (NHC = N-heterocyclic carbene). In comparison with the above tridentate complexes, bidentate bis­(aryloxide-NHC) palladium complex <b>3e</b> was also synthesized. All of these complexes were fully characterized by ¹H and ¹³C NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. The molecular structures of <b>3a</b>,<b>b</b>,<b>d</b>,<b>e</b> were determined by single-crystal X-ray diffraction analysis. On activation with either methylaluminoxane (MAO) or diethylaluminum chloride (Et₂AlCl), all palladium complexes exhibited excellent activities of up to 5.99 × 10⁷ g of PNB (mol of Pd)⁻¹ h^–1 toward norbornene addition polymerization, and the monomer conversion is up to 99.9%. Notably, the tridentate palladium complexes show better activities than the corresponding bidentate bis­(aryloxide-NHC) palladium complexes in the presence of MAO. The resulting polymers were soluble in CHCl₃ when the reactions were conducted in the presence of Et₂AlCl and were characterized by gel permeation chromatography (GPC)