Plant-derived products rely heavily on the availability of phosphorus (P) in the soil. With reserves of P-rocks being limited, there is a growing demand to enhance the efficiency of P utilization by crops. Eucalypts, an important economic crop in many countries, is a source of timber, coal, essence oils, and cellulose. After identifying low P tolerant and susceptible species in a previous study, we explored the various physiological and biochemical responses of these same species to low P availability. The aim was to expand our understanding of how different P-nutrition responses might impact eucalypt wood production and traits related to its quality. Our results indicate that low soil P minimally affects physiological wood parameters in the young trees of Eucalyptus acmenoides, Corymbia maculata, E. grandis, E. globulus, and E. tereticornis. Decreases in cellulose contents and increases in lignin content and syringyl and guaiacyl (S/G) ratios were observed under low P and only in E. acmenoides plants. Wood density remained unaffected in all species. Additionally, bark, stem, and root P concentrations increased under sufficient P conditions in E. globulus, E. grandis, and E. tereticornis. These findings suggest that these plant parts may act as reserve pools of this nutrient.

In Brazil, high-yield soybean [Glycine Max (L). Merrill] – corn (Zea mays L.) double cropping system might be nitrogen (N)-limited and additional N fertilization can be beneficial. Early application of N in soybean reduces the symbiotic N fixation (SNF) efficiency and/or establishment. One alternative to avoid SNF impairment is to apply N between the beginning pod (R3) and seed-fill (R5) stages through the use of controlled release fertilizers. In this study, N was applied at 50 kg ha−1 as common urea (CU) or controlled release urea (CRU) with different lag periods until N release starts (30 days, 60 days, or 1:1 mix of both lag times) in a randomized complete blocks design with six treatments and four replicates under tropical and subtropical conditions. CU was applied after soybean emergence (VE) or at the beginning pod (R3), and CRU only at VE. Using urea labeled with 15N isotope, we analyzed the N source used by soybean (fertilizer, soil, or SNF) and SNF parameters. On average, CRU – 30 days, CRU – 1:1 mix (30 + 60 days) and CU applied at the R3 stage increased grain yield by 9.2% (354 kg ha−1) compared to the control. N derived from all fertilizer treatment were almost 35 kg N ha−1, a high N recovery efficiency of 68%. The SNF was not impaired by CU and CRU and accounted for 71% (220 kg N ha−1) of total N uptake. In the conditions of the experiments, fertilization of 50 kg N ha−1 as CRU was shown to be effective to supply N in late soybean demand (R3 stage), increasing yield without damaging the SNF process in high-yield environments.

In Madagascar, upland rice cropping is constrained by soil acidity and low phosphorus (P) bioavailability. Given their role in plant P nutrition, arbuscular mycorrhizal fungi (AMF) may improve crop yield in nutrient-poor tropical soils. In the Vakinankaratra region, a field experiment was conducted at 908 m asl on an acidic Ferralsol during the 2019–2020 growing season. The aim was to test the ability of four promoted rice varieties to respond to AMF seed-coating inoculation with a commercial strain of Rhizophagus irregularis in the absence or presence of P fertilizer (20 kg ha−1 of P2O5) under no expected nitrogen (N) limitation. In absence of P fertilization, both at tillering and at maturity and irrespective of the rice varieties, AMF inoculation significantly improved plant performance and finally grain yield, grain N, and grain P amounts by an average of 28%, 30%, and 39%, respectively. In contrast, when P fertilizer was supplied, no significant effect of AMF inoculation was observed. Rice growth variables were significantly higher with the application of P fertilizer than with AMF inoculation both at tillering and at maturity. P fertilizer without inoculation provided an average grain yield improvement of 85%. At tillering, mycorrhizal parameters for root colonization assessment were not positively linked with rice growth variables suggesting an early effect of AMF inoculation. We concluded that, with no P fertilization, AMF seed coating inoculation at the field scale significantly improved upland rice plant performance in a limited soil P environment. Our rice genetic variability did not interfere significantly both with mycorrhizal parameters and crop AMF inoculation benefits.

Glyphosate is an important component of herbicide programs in orchard crops in California. It can be applied alone or in tank-mix combinations under the crop rows or to the entire field and often is used multiple times each year. There has been speculation about the potential impacts of repeated use of glyphosate in perennial crop systems, because of uptake from shallow root systems or indirectly because of effects on nutrient availability in soil. To address these concerns, research was conducted from 2013 to 2020 on key orchard crops to evaluate tree response to glyphosate regimens. Almond, cherry, and prune were evaluated in separate experiments. In each crop, the experimental design was a factorial arrangement of two soil types, four glyphosate rates (0, 1.1, 2.2, and 4.4 kg ae ha−1, applied three times annually), and two post-glyphosate application irrigation treatments. In the first 2 yr of the study, there was no clear impact of the glyphosate regimens on shikimate accumulation or leaf chlorophyll content, which suggested no direct effect on the crop. In the seventh year of the study, after six consecutive years of glyphosate application to the orchard floors, there were no negative impacts of glyphosate application on leaf nutrient concentration or on cumulative trunk growth in any of the three orchard crops. Lack of a negative growth impact even at the highest treatment rate, which included 18 applications of glyphosate totaling nearly 80 kg ae ha−1 glyphosate over the course of the experiment suggest there is not likely a significant risk to tree health of judicious use of the herbicide in these production systems. Given the economic importance of orchard crops in California, and grower and industry concerns about pesticides generally and specifically about glyphosate, these findings are timely contributions to weed management concerns in perennial specialty crops.

The increase of the absorption efficiency of boron (B) by plants is essential for increasing crop productivity. The intercalation of B in MgAl layered double hydroxides (LDHs) is an alternative to evaluating how these materials can provide B to plants. In this work, a MgAl LDH intercalated with borate ions (Mg2Al-B-LDH) was synthesized by the constant pH coprecipitation method, and the material produced was evaluated as a matrix for storage and as a source of B for plants. The Mg2Al-B-LDH was characterized by XRD, ATR-FTIR, TGA-DTA, specific surface area, pore size and volume, and SEM. A bioassay was performed to verify the supply of B to plants from the two sources in the forms of H3BO3 and of Mg2Al-B-LDH to sunflower plants grown in pots. The LDH basal spacing value of 12.0 Å is characteristic of intercalation of tetraborate octahydrate ions [B4O5(OH)42−]·8H2O between the layers. There was an increase in the dry matter (DM) and B content of the plants relative to those treatments where no B was added. The lack of statistical difference for plant yield between the two sources of B suggests a lack of stability of the Mg2Al-B-LDH structure under the acidic condition of the soil.

We tested the sulfur-modulated plant resistance hypothesis using potted cabbage (Brassica oleracea var. capitata) plants that were grown without and with increasing levels of sulfur fertilization. Changes in plant chemical traits were assessed and developmental performance of Plutella xylostella, a highly host-specific leaf-chewing insect, was followed. Leaf sulfur concentration gradually increased with growing addition of sulfur in soil; however, there was a generalized saturation response curve, with a plateau phase, for improvements in total leaf nitrogen, defense glucosinolates and insect performance. Plutella xylostella performed better in sulfur-fertilized cabbage probably because of the higher level of nitrogen, despite of the higher content of glucosinolates, which are toxic for many non-specialized insects. Despite the importance of sulfur in plant nutrition and production, especially for Brassica crops, our results showed that sulfur fertilization could decrease plant resistance against insects with high feeding specialization.

Introduction Mango (Mangifera indica L.) is a crop of major economic importance in the provinces of Malaga and Granada (SE Spain). A field experiment on mango trees was designed to determine the optimum irrigation scheduling over three seasons. The aim was to evaluate the impact of sustained-deficit irrigation (SDI) strategies on fruit yield and quality, tree growth, and mineral status under a Mediterranean subtropical climate. Materials and methods. Three sustained-deficit irrigation treatments were applied to mango trees: SDI-1 (33% ETc), SDI-2 (50% ETc) and SDI-3 (75% ETc). The stress treatments were compared with a control (C-100) irrigated at 100% ETC. The response of fruit yield, number of fruits, fruit size and quality, and macro- and micronutrients in leaves was determined. Results. The SDI-2 treatment proved to be the most appropriate SDI treatment, since it allowed the trees to reach the highest yield (18.4 t·ha-1) and the best water-use efficiency (7.14 kg·m-3). However, fruit size was higher for trees of the SDI-3 and C-100 treatments, since they reached significantly higher length and width. The total soluble solids were affected by the SDI treatments only for one year, being highest in fruits from trees of the SDI-1 and SDI-2 treatments. Macro- and micronutrients in the leaves were affected by the SDI treatment only for the P, Mg and Mn contents. Conclusion The SDI treatment providing 50% of ETC is recommended for mango orchards in order to attain the highest yields and the best water-use efficiency under a Mediterranean subtropical climate.

Introduction. The production of high quality fruit juice involves several cultural inputs. Among other factors, fruit quality attributes are influenced by the cultivar, the climate, the harvesting time and soil fertility. Particularly, the soil fertility has a significant effect on the nutritional characteristics of the juice. Good practice as regards fertilization consists of applying rates adapted to plant optimum growth, yield and fruit quality. Materials and methods. Effects of four poultry manure rates [(0, 5, 10 and 15) t·ha–1] on the juice quality of passion fruits (Passiflora edulis var. flavicarpa) were evaluated for two cropping years (2005 and 2006). The seedlings of passion fruit vine were field-established in a randomized complete block design, and the manure treatments were replicated four times. Juice quality assessment was performed on fruits picked in December 2005, coinciding with the dry season and low soil moisture recharge, and August 2006, during the wet season and high soil moisture recharge. Results. The results obtained indicated a significant poultry manure effect on all the juice quality parameters studied; the quality of the juice increased gradually as the manure rate increased. Similarly, the season of fruit-picking had a significant effect on the juice quality. As expected, vines that received no manure produced fruits with the poorest juice quality, suggesting unfavorable nutritive conditions within the vines. The concentrations of anti-nutrient factors (tannin, hydrogen cyanide, phytate and calcium oxalate) were low in ripe yellow passion fruits, and insignificant regarding health hazards for consumers of yellow passion fruit. Conclusion. The results obtained showed that the manure rate and the harvest period affected the quality of passion fruit juice. Application of 15 t·ha–1 poultry manure generally gave the best juice quality; similarly, fruits harvested in the first cropping season had better juice quality.

Introduction. Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) can be considered important rhizospheric beneficial microorganisms. Their use as biocontrol strategies against soilborne pathogens such as nematodes should be taken into account. However, optimal management of soil microbiota communities is not easy because of the high specificity involved in these types of interactions. The aim of our study was to determine whether the combined inoculation of two AMF species and a Bacillus consortium based on three strains previously described as PGPR in other crops were able to reduce nematode infection and damage on papaya. Materials and methods. Papaya seedlings were inoculated with two AMF isolates (Glomus mosseae or G. manihotis) at the beginning of the nursery phase. Once the mycorrhizal symbiosis was established, a Bacillus consortium was applied. Nematode inoculum was applied 20 d after transplanting to individual pots. Plants were harvested 160 d after nematode inoculation. Results. In terms of plant development and nutrition, benefits due to AMF inoculation persisted in the presence of PGPR. However, the effect of dual inoculation was different, depending on the Glomus species. This positive effect was also evident in plants with nematode. Meloidogyne infection was significantly reduced in mycorrhizal plants. However, the addition of PGPR does not seem to improve the results of AMF single treatments in terms of nematode infection. Conclusion. Dual application of AMF and PGPR must be considered for papaya threatened by the root-knot nematode, although a previous screening should be done in order to select the best microbe combination to optimise results.

Introduction. Mango (Mangifera indica L.) production is rising in various subtropical zones throughout the world. The main polyembryonic rootstocks used by growers in South-East Spain are Gomera 1 and Gomera 3 (from the Canary Islands) and the most commonly used cultivars are Osteen and Keitt (from Florida, US). In this marginal environment for mango growing, it is important to determine the different rootstock qualities in order to optimise fruit production. The objective of our study was to evaluate the performance of mango cv. Osteen and Keitt on the two aforementioned rootstocks, as measured by fruit yield, scion growth and mineral nutrition. Materials and methods. A 3-year study was conducted in a mature mango orchard (14 years old) of a total of 24 trees, where eight were grafted onto cv. Osteen, another eight onto Keitt (four trees with each of the G1-Ost, G3-Ost, G1-Kt and G3-Kt combinations) and eight were ungrafted rootstocks. Fruit yield and pomological characteristics were evaluated by measuring fruit length, width and weight. Height and canopy diameter, as well as the trunk circumference of the tree, were recorded. Throughout the study period, chemical foliar measurements were taken from all trees. Results. Fruit yield in G1-Ost and G3-Kt trees proved significantly higher than that in the others. The fruit weight and length with the G3-Kt combination were greater than those with G1-Kt. Both cultivars grafted on Gomera 3 rootstock had the highest height and canopy volume. The tree-size data confirmed the vigorous feature of the Gomera 3. The N and P foliar concentration was significantly higher for Gomera 3 than for Gomera 1 in both cultivars. The K concentration was higher in G3-Kt leaves than in G1-Kt ones, but higher in G1-Ost than in G3-Ost. The leaf Mn and Cu concentrations with G3-Kt significantly exceeded those of G1-Kt. Conclusion. The height, trunk cross-sectional area, and canopy volume and diameter proved to be the greatest with Gomera 3, reflecting the vigour of this rootstock. The combinations G1-Ost and G3-Kt registered the highest fruit yield, offering promising possibilities for boosting subtropical productivity in mango.

Introduction. The yellow passionfruit is consumed mainly as juice and is well accepted around the world. The nutritional state of the plant influences yield and fruit quality. We studied the particular effect of potassium nutrition on the quality of yellow passionfruit. Materials and methods. The experiments were conducted in a greenhouse at the Federal University of Viçosa, in Brazil, outlined in a randomized block design. The treatments were five concentrations of K [(1, 2, 4, 6 and 8) mmol·L–1] in a modified nutritive solution of Hoagland and Arnon. The experimental unit consisted of one plant in a 20-L pot containing washed sand. The plants were irrigated by a circulating hydroponic system. The nutrients were re-added to the solution based on its electric conductivity and on the K content in each solution. Results and discussion. The K supply increased yield and average fruit weight up to the concentration of (6.43 and 6.24) mmol·L–1, respectively, and linearly increased the number of seeds per fruit, thickness and relative water content of the pericarp and vitamin C content. The total titratable acid content increased according to a square equation, with the maximum point at 5.27 mmol K ·L–1. The pulp percentage, pH and total soluble solids content were not influenced by K doses. Conclusions. The increase in K supply promoted yield and fruit quality. At 90% of the maximum yield, the fruits had adequate quality traits.

Roots of nine of the 12 vascular plant species present on sub-Antarctic Heard Island were examined for mycorrhizae. All species examined had some type of mycorrhization with most possessing associations with vesicular-arbuscular mycorrhizae or dark septate mycorrhizae. The degree of mycorrhization varied considerably across sites. Sampled plants were growing on either morainic or beach substrates with some areas exposed only in the last century. As mycorrhizae are known to play an important role in the nutrient uptake by host-plants, these results support the idea that mycorrhizae can influence the capacities of plants to colonize in cold and low-nutrient environments such as sub-Antarctic glacier forelands. Comparisons with data from other sub-Antarctic islands are made.

Introduction. Rhizobacterial inoculation in low fertilizer-N conditions, viz., 33% fertilizer-N of the total N requirement, could produce similar plant growth to the 100% N-fertilization of banana plantlets grown under hydroponic conditions. Thus, we tested PGPR inoculation in combination with fertilizer-N application to study the role played by strains of rhizobacteria in nutrient accumulation, nitrogen fixation and, consequently, improvement in yield and fruit quality of bananas. Materials and methods. Two PGPR strains were used in the experiments, namely, Sp7 (Azospirillum brasilense) and UPMB10 (Bacillus sphaericus). The design of the experiment was completely randomized with three replications. Eight treatments were applied: control without fertilizer-N application (N0%) and without PGPR; N0% + Sp7; N0% + UPMB10; N33% without PGPR; N33% + Sp7; N33% + UPMB10; N100% without PGPR and N100% + UPMB10. One tissue-cultured banana (cv. ‘Berangan’) plantlet was planted in a plastic pot (4 L) for 45 days and thereafter transferred to a larger polyethylene tank (1000 L) until maturity. A 100-mL broth culture of Sp7 or UPMB10 was added to the respective tanks after the transplanting process and repeat inoculations were performed monthly. The fruits were harvested at the maturity stage after 80–90 days of flowering. After ripening, yield and fruit quality parameters were assessed. Results. Inoculation with 33% fertilizer-N increased the total nutrient accumulation (N, P, K, Ca and Mg). PGPR inoculation along with 33% fertilizer-N significantly increased the bunch yield and fruit physical attributes, namely, finger weight, length and diameter, and [pulp / peel] ratio, besides inducing early flowering by 3 weeks. Conclusion. The results suggested that PGPR strains Sp7 and UPMB10 could be used as bioenhancer and biofertilizer for early, high-yielding and improved banana fruit production in 33% fertilizer-N conditions.

Introduction. The causal agent of Panama disease in banana is Fusarium oxysporum f. sp. cubense (FOC). The authors put forward a hypothesis to account for certain disturbances of the natural defence mechanisms of banana plants against Panama disease as a consequence of very low Zn levels which could alter the mechanism of tylose formation. Materials and methods. A long-term experiment was carried out with 2-month-old banana plants in a growth chamber at 23 °C using three different levels of Zn nutrition. The nutrient solutions were inoculated with FOC 1 and FOC 4. Results and discussion. None of the total plants growing in a nutrient solution inoculated with FOC 1 showed infected rhizomes at the end of the experiment, but 75% of the plants growing in pots inoculated with FOC 4 had infected rhizomes. On the other hand, rhizome infection by FOC 4 was influenced by the nutrient solutions. The data showed that the number of plants with damaged rhizomes was significantly higher in the Zn-deficient treatments (100% of plants) than in the normal Zn solution (25% of plants), these internal symptoms being seen to worsen as the presence of Zn decreased in the nutrient solution. Conclusions. The results obtained seem to confirm the role played by Zn nutrition of banana plants in the appearance of Panama disease and are in accordance with our hypothesis concerning the relationships among plant Zn nutrition, plant IAA level, tylose formation and the incidence of the disease. Likewise, under our experimental conditions, race 1 of FOC is confirmed to be non-pathogenic against this banana cultivar, while race 4 is indeed pathogenic.

Introduction. Research on the mineral nutrition of Barbados cherry is scarce. Leaf sampling techniques for this crop are unknown. Leaf analysis, associated with the determination of the nutrient availability in the soil, can provide reliable orientation for the establishment of fertilizer programs. For a correct interpretation of the nutritional status, it is important (1) to evaluate the seasonal variation of nutrient contents in the leaves, (2) to determine the appropriate time for leaf sampling and analysis, and (3) to indicate the best part of the plant for determination of the nutritional status. These subjects were the three objectives of this study. Materials and methods. The experiment was conducted from March 1997 to February 1998 in Visconde do Rio Branco, Minas Gerais, Brazil. The dynamics of the elements N, P, K, Ca, Mg, S, Fe, Cu, Zn and Mn were studied in leaves at the apical, median and basal positions of branches located in the upper, median and lower portions of the plant canopy. Results. The minimum variation in the foliar contents occurred at the medium third of the branches located in the upper portion of the canopy. So, these parts are the most appropriate for leaf sampling. Moreover, December was characterized as the appropriate time for leaf sampling. Conclusion. The leaf sampling techniques developed will allow better study of the mineral nutrition of M. emarginata in order to establish reliable fertilizer programs and to improve the yields of this fruit tree.

The floristic composition, structure, soil fertility and leaf nutrient concentrations were analysed in a monodominant forest of Brosimum rubescens Taub. located in the Areões Xavante Indigenous Reserve (14°34′S, 51°58′W). The area lies in the ecotone between Amazonian forest and cerrado in the municipality of Água Boa, Mato Grosso State, Brazil. Sixty nested plots (10 × 10m each) were located in a representative portion of the forest, giving a total sampling area of 0.6ha (40 × 150m). A total of 609 trees ≥ 5cm dbh belonging to 57 species, 46 genera and 32 families were present. The most important family was Moraceae, with B. rubescens as the dominant species with a relative dominance of 59%. The diameter distribution of B. rubescens was unbalanced, indicating an episodic recruitment that could lead to future changes in the forest structure. The high basal area per hectare of B. rubescens indicates the possibility of sustainable logging for commercial exploitation. Analysis of composite soil samples collected from the surface layer (0–10cm) of each of the 60 plots did not indicate any significant gradients in fertility within the area sampled. Mean soil pH was 4.6 and the availability of essential nutrients was very low (0.22cmol(+) kg−1 K, 0.048cmol(+) kg−1 Ca, 0.167cmol(+) kg−1 Mg, and 1.5mg kg−1 P). The higher availability of Mg in the soils in comparison with Ca was a feature observed in other monodominant forests in the Amazon region, as well as in other parts of the world. Analysis of foliar samples showed that the dominant species, B. rubescens, maintained higher foliar concentrations of K, Ca and Mg than other species in the forest. This probably indicates a competitive advantage for this species. Also, the higher concentrations of Mg in the soil did not affect its uptake of Ca or K.

Introduction. To compare the mineral nutrition of organically and normally grown bananaplants, observations were made on growth and yield of organic banana plants, at the Canary Islands. Thedata were then discussed opposite the results previously reported for conventional plantations.Materials and methods. Growth parameters (plant height, leaf emission rate, pseudostemcircumference) and yield parameters (bunch weight, number of hands, finger grade, etc.) were measuredduring ten months on an organically grown banana plantation of Dwarf Cavendish cv. Leaf N, P, K, Ca, Mg,Cu, Fe, Mn and Zn contents were also assessed. Results and discussion. Leaf emission rates showedhigher values in late spring and early summer (0.099-0.109 leaf $\cdot$ d-1), while pseudostemcircumference grew more in late spring (0.238 cm $\cdot$ d-1) than in summer. In August, pseudostemcircumference decreased dramatically, probably because the plants with a larger circumference had floweredbefore that month and could not be measured. Bunches gave good yields for the zone (43.59 kg on average)and had a high mean number of hands (12.79). Number of fingers of the second upper hand (25.63), theirgrade (37.63 cm), length (23.50 cm) and weight (165.19 g) ranged from normal to high. Month of harvestinginfluenced yield and quality of the fruits. Leaf content of N, P, Mg, Cu, Fe, Mn and Zn fell within thenormal range related to the conventionally grown banana plants. Potassium foliar content showed low levelsbut not deficiencies, whereas Ca leaf concentrations were high but not excessive. No relationship wasfound among leaf nutrient levels and growth, yield and fruit quality parameters.

Changes in the physiological status of the host rice plant had a profound effect on wing morphism in the brown planthopper, Nilaparvata lugens (Stål). Significant increases in macroptery in the hopper progenies reared on senescent or hopperburned hosts occurred mainly because of a general decline in the host's nutritional status and allelochemic factors. Starvation of young nymphs on nutritionally-depleted hosts probably inhibits the secretion of juvenile hormone by the corpus allatum, suppressing brachyptery and expressing macroptery. Also, any juvenilizing effect of the host's allelochemics would tend to dissipate with the host's senescence. Therefore, the proportion of macroptery in the hopper progeny developing on the rice host plant is determined by the extent of depletion of the host's nutritional allelochemic factors. The observed significant increase in macroptery at a density of 50 or more hoppers per plant may have also been mediated through the host plant. Brown planthopper progenies of macropterous and brachypterous Biotypes 1, 2, 3 and the field population differed in their expression of macroptery probably because of their inherent differences in sensitivity to macropteryinducing stresses.