Coffee Orchard Response to Enhanced Efficiency Phosphate Fertilizer

Phosphorus (P) plays a crucial role in plant growth by aiding in the development of strong roots, promoting flower and fruit formation, and aiding in photosynthesis. Studies to improve P fertilizers efficiency in coffee orchards are necessary due to the need for better efficiency and the lack of information on enhanced efficiency P fertilizers. This study aimed to investigate the effect of MAP coated with anionic polymers (Policote) on coffee orchard development. A coffee trial was carried out in a randomized block design with three replications. The treatments, applied at coffee planting, were arranged in an incomplete factorial (2 × 4) + 1, using two P sources (MAP and Policote coated MAP), four P rates (40, 80, 120, and 160 g P2O5 plant-1) and control (without application of P fertilizer). Plant height was evaluated in the 2016/2017, 2017/2018, and 2018/2019 seasons, while coffee bean maturation, yield, and agronomic P efficiency use were evaluated in the last two seasons. P fertilization did not affect coffee bean maturation and increased coffee yield in 31-month-old plants when differences among P sources and rates were observed. Using Policote-coated P fertilizer resulted in higher yields at the same P rate, as well as similar yields at a lower P rate, compared to conventional fertilizer. Policote-coated P fertilizer can be used as an enhanced efficiency fertilizer and is an efficient way to deliver required P to plants. The target for reducing farm investment, increasing agricultural profits, preserving phosphatic rock reserves, and avoiding the overuse of phosphate fertilizer could be realized through the rational use of enhanced efficiency fertilizers.

Genetic Improvement of Root Growth Contributes to Efficient Phosphorus Acquisition in maize (Zea mays L.)

Maize plants adapt to low phosphorus （P） stress by increasing root growth. It is of importance to know the extent to which genetic improvement of root growth can enhance P acquisiton. In the present study, the contribution of root growth improvement to efficient P acquisition was evaluated in two soils using T149 and T222, a pair of near isogenic maize testcrosses which were derived from a backcross BC 4 F 3 population. T149 and T222 showed no difference in shoot biomass and leaf area under normal growth conditions, but differed greatly in root growth. T149 had longer lateral roots and a larger root surface area compared to T222. In calcareous soil, when P was insufficient, i.e., when P was either supplied as KH 2 PO 4 at a concentration of 50 mg P kg-1 soil, or in the form of Phy-P, Ca3-P or Ca10-P, a 43% increase in root length in T149 compared to T222 resulted in an increase in P uptake by 53%, and shoot biomass by 48%. In acid soil, however, when P supply was insufficient, i.e., when P was supplied as KH 2 PO 4 at a concentration of 100 mg P kg-1 soil, or in the form of Phy-P, Fe-P or Al-P, a 32% increase in root length in T149 compared to T222 resulted in an increase in P uptake by only 12%, and shoot biomass by 7%. No significant differences in the exudation of organic acids and APase activity were found between the two genotypes. It is concluded that genetic improvement of root growth can efficiently increase P acquisition in calcareous soils. In acid soils, however, improvements in the physiological traits of roots, in addition to their size, seem to be required for efficient P acquisition.

Development of Root Phenotyping Platforms for Identification of Root Architecture Mutations in EMS-Induced and Low-Path-Sequenced Sorghum Mutant Population

Sorghum’s natural adaptation to a wide range of abiotic stresses provides diverse genetic reserves for potential improvement in crop stress tolerance. Growing interest in sorghum research has led to the expansion of genetic resources though establishment of the sorghum association panel (SAP), generation of mutagenized populations, and recombinant inbred line (RIL) populations, etc. Despite rapid improvement in biotechnological tools, lack of efficient phenotyping platforms remains one of the major obstacles in utilizing these genetic resources. Scarcity of efforts in root system phenotyping hinders identification and integration of the superior root traits advantageous to stress tolerance. Here, we explored multiple approaches in root phenotyping of an ethyl methanesulfonate (EMS)-mutagenized sorghum population. Paper-based growth pouches (PGP) and hydroponics were employed to analyze root system architecture (RSA) variations induced by mutations and to test root development flexibility in response to phosphorus deficiency in early growing stages. PGP method had improved capabilities compared to hydroponics providing inexpensive, space-saving, and high-throughput phenotyping of sorghum roots. Preliminary observation revealed distinct phenotypic variations which were qualitatively and quantitatively systemized for association analysis. Phenotypes/ideotypes with root architecture variations potentially correlated with Pi acquisition were selected to evaluate their contribution to P-efficiency (PE). Sand mixed with P-loaded activated alumina substrate (SAS) provided closely to natural but still controlled single-variable conditions with regulated Pi availability. Due to higher labor and cost input we propose SAS to be used for evaluating selected sorghum candidates for PE. The ability of rapidly screening root phenotypes holds great potential for discovering genes responsible for relevant root traits and utilizing mutations to improve nutrient efficiency and crop productivity.

Efficient Annealing-Free P3HT:PC61BM-Based Organic Solar Cells by Using a Novel Solvent Additive without a Halogen or Sulphur Atom

The power conversion efficiency （PCE） of poly（3-hexylthiophene） （P3HT） and [6,6]-phenyl C61-butyric acid methyl ester （P061BM） based organic solar cells （OSCs） is significantly improved by using benzyl acetate （BA）, an organic compound without any halogen or sulphur atom, as a processing additive to control the blend morphology. The solar cells show PCE of 3.85% with a fill factor （FF） of 65.22%, which are higher than those of the common thermal annealing device （PCE 3.30%, FF 60.83%）. The overall increased PCE depends upon the enhanced crystallinity of P3HT and good carriers transport, with a high balanced charge carrier mobility.

Determining the optimum range of soil Olsen P for high P use efficiency, crop yield, and soil fertility in three typical cropland soils

Soil Olsen P level has a major influence on crop yield,efficient P utilization,and soil fertility.In this study,the optimum Olsen P range was determined from long-term(1990–2012)field experiments in three typical soil types of China under single cropping of maize or double cropping of maize and wheat.The critical soil Olsen P value for crop yield was evaluated using three different models,and the relationships among P use efficiency(PUE),Olsen P,and total P were analyzed.The agronomic critical soil Olsen P values obtained from the three models for the neutral soil of Gongzhuling and the calcareous soil of Zhengzhou were similar;however,the values from the linear-linear and linear-plateau models for both maize and wheat were substantially lower than those from the Mitscherlich model for the acidic soil of Qiyang.The PUE response change rates(linear equation slopes)under different soil Olsen P levels were small,indicating slight or no changes in the PUE as the soil Olsen P increased in all three soils.A comparison of the Olsen P levels that achieved the maximal PUE with the agronomic critical values derived from the three models indicated that the linear-plateau model exhibited the best performance.The regression equation coefficients of Olsen P response to total P decreased as follows:Zhengzhou(73 mg g-1)>Qiyang(65 mg g-1)>Gongzhuling(55 mg g-1).The Olsen P level increased as the total P increased,which may result in a decrease in PUE.To achieve a relatively high crop yield,PUE,and soil fertility,the optimum Olsen P range should be 13–40,10–40,and 29–40 mg kg-1 at Gongzhuling,Zhengzhou,and Qiyang,respectively.

Molecular mechanisms underlying phosphate sensing, signaling, and adaptation in plants

As an essential plant macronutrient, the low availability of phosphorus （P） in most soils imposes serious limitation on crop production. Plants have evolved complex responsive and adaptive mechanisms for acquisition, remobilization and recycling of phosphate （Pi） to maintain P homeostasis. Spatio-temporal molecular, physiological, and biochemical Pi deficiency responses developed by plants are the consequence of local and systemic sensing and signaling pathways. Pi deficiency is sensed locally by the root system where hormones serve as important signaling components in terms of developmental reprogramming, leading to changes in root system architecture. Root-to-shoot and shoot-to-root signals, delivered through the xylem and phloem, respectively, involving Pi itself, hormones, miRNAs, mRNAs, and sucrose, serve to coordinate Pi deficiency responses at the whole-plant level. A combination of chromatin remodeling, transcriptional and posttranslational events contribute to globally regulating a wide range of Pi deficiency responses. In this review, recent advances are evaluated in terms of progress toward developing a comprehen- sive understanding of the molecular events underlying control over P homeostasis. Application of this knowledge, in terms of developing crop plants having enhanced attributes for P use efficiency, is discussed from the perspective of agricultural sustainability in the face of diminishing global P supplies.

Soil phosphorus availability and rice phosphorus uptake in paddy fields under various agronomic practices

Agronomic practices affect soil phosphorus(P) availability, P uptake by plants, and subsequently the efficiency of P use. A field experiment was carried out to investigate the effects of various agronomic practices(straw incorporation, paddy water management, nitrogen(N) fertilizer dose, manure application,and biochar addition) on soil P availability(e.g., soil total P(STP), soil available P(SAP), soil microbial biomass P(SMBP), and rice P uptake as well as P use efficiency(PUE)) over four cropping seasons in a rice-rice cropping system, in subtropical central China. Compared to the non-straw treatment(control,using full dose of chemical N fertilizer), straw incorporation increased SAP and SMBP by 9.3%–18.5% and 15.5%–35.4%, respectively;substituting half the chemical N fertilizer dose with pig manure and the biochar application increased STP, SAP, and SMBP by 10.5%–48.3%, 30.2%–236.0%, and 19.8%–72.4%,respectively, mainly owing to increased soil P and organic carbon inputs;adding a half dose of N and no N input(reduced N treatments) increased STP and SAP by 2.6%–7.5% and 19.8%–33.7%, respectively, due to decreased soil P outputs. Thus, soil P availability was greatly affected by soil P input and use. The continuous flooding water regime without straw addition significantly decreased SMBP by 11.4% compared to corresponding treatments under a mid-season drainage water regime. Total P uptake by rice grains and straws at the harvest stage increased under straw incorporation and under pig manure application, but decreased under the reduced N treatments and under biochar application at a rate of 48 t ha-1, compared to the control. Rice P uptake was significantly positively correlated with rice biomass, and both were positively correlated with N fertilizer application rates, SAP, SMBP, and STP. Phosphorus use efficiency generally increased under straw incorporation but decreased under the reduced N treatments and under the manure application(with excessive P input), compared to the control. These results showed that straw incorporation can be used to increase soil P availability and PUE while decreasing the use of chemical P fertilizers. When substituting chemical fertilizers with pig manure, excess P inputs should be avoided in order to reduce P accumulation in the soil as well as the environmental risks from non-point source pollution.