The application of agrochemical sprays to the aerial parts of crop plants is an important agricultural practice world-wide. While variable effectiveness is often seen in response to foliar treatments, there is abundant evidence showing the beneficial effect of foliar fertilizers in terms of improving the metabolism, quality, and yields of crops. This mini-review is focused on the major bottlenecks associated with the uptake and translocation of foliar-applied nutrient solutions. A better understanding of the complex scenario surrounding the ultimate delivery of foliar-applied nutrients to sink cells and organs is essential for improving the effectiveness and performance of foliar fertilizers.

为研究生物刺激剂对玉米的增产提质效果,试验探讨不同生物刺激剂对玉米的产量和品质方面的影响,为鲜食玉米的优质高产栽培提供技术支撑。以鲜食玉米‘钱江糯3号’为试验品种,以3种生物刺激剂（阿美滋、美基、保康灵1号）为供试药剂,设置6个处理（阿美滋1000倍液、阿美滋1500倍液、阿美滋2000倍液、美基3000倍液、保康灵1号300倍液、清水对照）,研究大田常规施肥水平下药剂对‘钱江糯3号’的经济性状、产量及品质的影响。在阿美滋1500倍液喷施下,玉米的行粒数、单穗鲜重和单穗净重、产量均最高,蛋白质含量、粗纤维含量、还原糖含量、淀粉含量均居第3位;在保康灵1号300倍液喷施下,玉米的穗粗最高,单穗鲜重、单穗净重、产量均居第2位,蛋白质含量最高,脂肪含量最低,还原糖含量居第2位。阿美滋1500倍液在增加玉米产量上是最佳选择,保康灵1号300倍液则对提升玉米品质最有效果。建议生产上将阿美滋1500倍液与保康灵1号300倍液配合施用,这对鲜食玉米的增产提质效果最好。

Soils underpin terrestrial ecosystem functions, but they face numerous anthropogenic pressures. Despite their crucial ecological role, we know little about how soils react to more than two environmental factors at a time. Here, we show experimentally that increasing the number of simultaneous global change factors (up to 10) caused increasing directional changes in soil properties, soil processes, and microbial communities, though there was greater uncertainty in predicting the magnitude of change. Our study provides a blueprint for addressing multifactor change with an efficient, broadly applicable experimental design for studying the impacts of global environmental change.Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Effects of CeO NPs (200 mg.L) on rice (Oryza sativa L.) alone or co-exposure with cadmium (Cd) and salt (sodium chloride, NaCl) were investigated in hydroponic systems for two weeks. Physiological results show that rice biomass was significantly inhibited when NaCl or CdCl added alone or in co-exposure treatment. CeO NPs significantly relieve the chlorophyll damage under CdCl environmental stress. The presence of CeO NPs alleviated both stressors induced damages to rice as indicated by the reduced proline level. Additionally, CeO NPs triggered the antioxidant defense systems to counteract the oxidative stress caused by NaCl and CdCl. The level of 8-OHdG, one of the most important indicators for genotoxicity, in rice suggest that the presence of CeO NPs reduced the DNA damage in NaCl treated rice. Elemental analysis indicated that co-exposure to NaCl and CdCl slightly decreased the Cd content as compared to the one in the CdCl alone treatment, and this co-exposure also significantly reduced the Na content when comparing with the NaCl alone treatment. Taken together, our findings suggest that CeO NPs could alleviate the CdCl and NaCl stresses, but could not completely change the phenotype of both contaminants treated rice.Copyright © 2019 Elsevier Ltd. All rights reserved.

Nano-materials ameliorate the adverse effect of salinity stress on the physiological and biochemical processes in plants. The present investigation was designed to evaluate the physiological mechanisms through which a nano-chitosan-encapsulated nano-silicon fertilizer (NC-NS) can ameliorate the adverse effect of salinity stress on the wheat plants, and compare it with nano-chitosan (NC) and nano-silicon (NS) application. Nano-silicon was encapsulated with a chitosan-tripolyphosphate (TPP) nano-matrix by ionic gelation method for its slow release. The wheat plants were exposed to foliar application of distilled water, NC, NS, and NC-NS with two NaCl irrigation levels at 0 (distilled water) and 100 mM.The foliar application of NC, NS, and NC-NS induced a significant increase in the function of enzymatic and non-enzymatic antioxidant systems of the wheat plants to equilibrate cellular redox homeostasis by balancing HO content in the leaves and roots, as compared with salt-stressed plants without treatment. The plant's foliar-sprayed with NC, NS, and NC-NS solution exhibited a significant increase in the molecules with osmotic adjustment potentials such as proline, free amino acids, glycine betaine, and sugars to protect cells against osmotic stress-induced by salinity. The observed increase in the antioxidant power and osmoregulatory at NC, NS, and NC-NS application was accompanied by the protection of lipid membrane, proteins and photosynthetic apparatus against salinity stress.In the present study, the beneficial role of NC, NS, and NC-NS application, particularly NC-NS, in alleviating the adverse effect of salinity stress on antioxidant systems and osmotic adjustment in wheat is well documented. An overview of the result of present study assists researchers in providing a potential solution for this increasing salinization threat in crops.© 2022. The Author(s).

The role of amorphous silica nanoparticles (SiNPs) in enhancing growth and yield of cucumber under water deficit and salinity stresses was assessed. A field experiment under greenhouse conditions was established using 4 different levels of SiNPs (100, 200, 300 and 400 mg kg) and 3 different watering regimes calculated based on crop evapotranspiration (ET) (100, 85 and 70% of ET). Electrical conductivity and sodium adsorption ratio of irrigation water were 1.7 dS m and 4.63 respectively. The results revealed that SiNPs improved growth and productivity of cucumber regardless of quantity of supplied water; however, the greatest increase corresponded to irrigating cucumber at the rate of 85% of ET. Applying SiNPs at rate of 200 mg kg showed the greatest increase specially when cucumber plants received 85% of their ET causing an increase of 20, 51 and 156% in plant height, chlorophyll and fruit yield, respectively, compared to untreated plants. These increases could be due to alerting nutrient uptake as SiNPs clearly increased contents of nitrogen (by 30%), potassium (by 52, 75 and 41% in root, stem and leaf, respectively) and silicon (by 51, 57, 8 and 78% in root, stem, leaf and fruit, respectively). Otherwise, same treatment reduced sodium uptake by 38, 77 and 38% in root, stem and leaf, respectively; consequently, potassium-sodium ratio increased by 149, 735 and 127% in root, stem and leaf, respectively. The significant role of SiNPs in mitigating water deficit and salinity stresses could be referred to high silicon content found in leaf which regulates water losses via transpiration. Also, high K content found in roots of cucumber helps plants to tolerate abiotic stresses as a result of maintaining ion homeostasis and regulating the osmotic balance as well as controlling stomatal opening which helps plants to adapt to salinity and water deficit stresses.Copyright © 2019 Elsevier Masson SAS. All rights reserved.

在施肥总量相同基础上,以马铃薯品种合作88号为试材,于现蕾后分别叶面喷施0.5%尿素、0.3%KH2PO4及其混合溶液各3次,每次喷液量为1 500kg/hm2,研究叶面追肥对马铃薯干物质积累、营养状况及土壤养分的影响。结果表明:不同叶面追肥对马铃薯及土壤的影响有较大差异。其中喷施0.5%尿素或0.5%尿素+0.3%KH2PO4处理能明显提高马铃薯干物质积累量、生物产量、鲜薯经济产量及叶片氮含量,但明显降低了土壤有机质、氮及磷含量;喷施0.3%KH2PO4处理对马铃薯叶片和土壤钾含量提高作用最为明显,但显著降低块茎氮、磷及钾含量。可见,在设置试验条件下,叶面追施氮肥的增产效果较好。

The present study investigated the role of trichomes in absorption of foliar-applied zinc fertilizers in soybean and tomato. Using synchrotron-based X-ray fluorescence microscopy for in situ analyses of hydrated leaves, we found that upon foliar application of ZnSO4, Zn accumulated within 15 min in some non-glandular trichomes in soybean, but not in tomato. However, analyses of cross-sections of soybean leaves did not show any marked accumulation of Zn in tissues surrounding trichomes. Furthermore, when near-isogenic lines of soybean differing 10-fold in trichome density were used to compare Zn absorption, it was found that foliar Zn absorption was not related to trichome density. Therefore, it is suggested that trichomes are not part of the primary pathway through which foliar-applied Zn moves across the leaf surface in soybean and tomato. However, this does not preclude trichomes being important in other plant species, as they are known to be highly diverse. We also compared the absorption of Zn when supplied as either ZnSO4, nano-ZnO, or bulk-ZnO, and found that absorption from ZnSO4 was about 10-fold higher than from nano- and bulk-ZnO, suggesting that it was mainly absorbed as soluble Zn. This study improves our understanding of the absorption of foliar-applied nutrients.