NPK uptake and growth of maize on ombrogenous peat as affected by the application of mycorrhizal fungal multi-spores and compound fertilizers

This study investigated the effectiveness of mycorrhizal fungal multi-spores and inorganic fertilizers in increasing NPK uptake and growth of maize on ombrogenous peat soils in Riau. The experiment, which was carried out in a plastic house, was arranged in a completely randomized design (CRD) with two factors, consisting of five replications. The first factor was the application of mycorrhizal fungal multi-spores, consisting of two levels (with and without application). The second factor was the application of inorganic fertilizer, consisting of three levels (P0: without fertilizer, PM-1: mixture of 225 kg Urea + 100 kg SP-36 + 75 kg KCl + 1000 kg Dolomite, and PM-2: mixture of 450 kg Urea + 200 kg SP-36 + 150 kg KCl +2000 kg Dolomite). Observed data consisted of agronomic observations, soil observations, and mycorrhiza observations. Agronomic observations consisted of plant height, root dry weight, shoot dry weight, and N, P, K nutrient uptake, and soil observations consisted of total and available N, P, K nutrients in the soil. Meanwhile, mycorrhiza observations consisted of infected roots and spore populations. The data obtained were then analyzed using DMRT to see the significant effect of the treatments. There was no interaction effect of mycorrhiza and compound fertilizer on the variables of shoot and root dry weight, but the interaction effect was observed on the variables of of shoot N, P, K uptake and root P and K uptake.

The effect of increasing temperature on crop photosynthesis: From enzymes to ecosystems

As global land surface temperature continues to rise and heatwave events increase in frequency, duration, and/or intensity, our key food and fuel cropping systems will likely face increased heat-related stress. A large volume of literature exists on exploring measured and modelled impacts of rising temperature on crop photosynthesis, from enzymatic responses within the leaf up to larger ecosystem-scale responses that reflect seasonal and interannual crop responses to heat. This review discusses (i) how crop photosynthesis changes with temperature at the enzymatic scale within the leaf; (ii) how stomata and plant transport systems are affected by temperature; (iii) what features make a plant susceptible or tolerant to elevated temperature and heat stress; and (iv) how these temperature and heat effects compound at the ecosystem scale to affect crop yields. Throughout the review, we identify current advancements and future research trajectories that are needed to make our cropping systems more resilient to rising temperature and heat stress, which are both projected to occur due to current global fossil fuel emissions

Sustainable Cropping Systems

Global crop production must substantially increase to meet the needs of a rapidly growing population. This is constrained by the availability of nutrients, water, and land. There is also an urgent need to reduce the negative environmental impacts of crop production. Collectively, these issues represent one of the greatest challenges of the twenty-first century. Sustainable cropping systems based on ecological principles are the core of integrated approaches to solve this critical challenge. This special issue provides an international basis for revealing the underlying mechanisms of sustainable cropping systems to drive agronomic innovations. It includes review and original research articles that report novel scientific findings on improvement in cropping systems related to crop yields and their resistance to biotic and abiotic stressors, resource use efficiency, environmental impact, sustainability, and ecosystem services

Identification and QTL mapping of physiological drivers of soybean yield under contrasting management systems using high-throughput phenotyping

Rapid characterization of physiological traits driving yield are becoming desirable aides to breeding programs to increase the rate of genetic gain. Each chapter in this dissertation investigates areas related to high-throughput phenotyping and physiological traits driving soybean yield. Chapter two seeks to understand the response of diverse soybean germplasm to seeding rate. An evaluation of final plot seed yield, seed protein percentage, seed oil percentage, seed weight, height, maturity, and plant lodging revealed a significant genotype x seeding rate interaction only for lodging, suggesting current soybean germplasm and soybean of wide genetic ancestry respond similarly to seeding rate. Our second objective was to identify physiological traits at multiple growth stages predicting yield response under contrasting levels of seeding rate. Adaptive elastic net models characterized diverging traits between seeding rates and determined chlorophyll traits as the leading predictors across seeding rates. Chapter three quantifies biomass partitioning strategies and residue quality determined through carbon:nitrogen (C:N) ratios in the same diverse panel of SoyNAM genotypes in Chapter 2. Above-ground plant components were dissected at three reproductive stages and revealed significant differences in biomass partitioning by R4. Significant genetic variation in C:N residue quality was found with no apparent negative relationship to final grain yield. Optimal biomass partitioning strategies for yield and improved residue C:N ratios for whole-system nitrogen sustainability can be targeted for yield improvement. Lastly, chapter four includes a QTL mapping study of vegetative indices used for yield prediction in Chapter 1 in four SoyNAM RIL populations derived from five of the 32 parent NAM genotypes evaluated in Chapters 1 and 2. Five QTL were detected for grain yield and vegetative indices NDVI, NMDI, NWIB, PSRI, and VREI2 measured at R5, spanning chromosomes 1, 3, 10 and 18. These QTL can serve as aides to MAS in soybean breeding and inform future studies aimed at dissecting the physiology of soybean grain yield. The overall research provides insights on soybean biomass partitioning and evidence of the presence of genetic variation in residue traits; physiological traits to predict yield in diverse germplasm and row-density management systems; and genomic regions mapped to spectral wavelengths related to soybean seed yield

The effect of increasing temperature on crop photosynthesis: from enzymes to ecosystems.

As global land surface temperature continues to rise and heatwave events increase in frequency, duration, and/or intensity, our key food and fuel cropping systems will likely face increased heat-related stress. A large volume of literature exists on exploring measured and modelled impacts of rising temperature on crop photosynthesis, from enzymatic responses within the leaf up to larger ecosystem-scale responses that reflect seasonal and interannual crop responses to heat. This review discusses (i) how crop photosynthesis changes with temperature at the enzymatic scale within the leaf; (ii) how stomata and plant transport systems are affected by temperature; (iii) what features make a plant susceptible or tolerant to elevated temperature and heat stress; and (iv) how these temperature and heat effects compound at the ecosystem scale to affect crop yields. Throughout the review, we identify current advancements and future research trajectories that are needed to make our cropping systems more resilient to rising temperature and heat stress, which are both projected to occur due to current global fossil fuel emissions

A Research Road Map for Responsible Use of Agricultural Nitrogen

Nitrogen (N) is an essential but generally limiting nutrient for biological systems. Development of the Haber-Bosch industrial process for ammonia synthesis helped to relieve N limitation of agricultural production, fueling the Green Revolution and reducing hunger. However, the massive use of industrial N fertilizer has doubled the N moving through the global N cycle with dramatic environmental consequences that threaten planetary health. Thus, there is an urgent need to reduce losses of reactive N from agriculture, while ensuring sufficient N inputs for food security. Here we review current knowledge related to N use efficiency (NUE) in agriculture and identify research opportunities in the areas of agronomy, plant breeding, biological N fixation (BNF), soil N cycling, and modeling to achieve responsible, sustainable use of N in agriculture. Amongst these opportunities, improved agricultural practices that synchronize crop N demand with soil N availability are low-hanging fruit. Crop breeding that targets root and shoot physiological processes will likely increase N uptake and utilization of soil N, while breeding for BNF effectiveness in legumes will enhance overall system NUE. Likewise, engineering of novel N-fixing symbioses in non-legumes could reduce the need for chemical fertilizers in agroecosystems but is a much longer-term goal. The use of simulation modeling to conceptualize the complex, interwoven processes that affect agroecosystem NUE, along with multi-objective optimization, will also accelerate NUE gains

High-throughput field phenotyping in cereals and implications in plant ecophysiology

[eng] Global climate change effects on agroecosystems together with increasing world population is already threatening food security and endangering ecosystem stability. Meet global food demand with crops production under climate change scenario is the core challenge in plant research nowadays. Thus, there is an urgent need to better understand the underpinning mechanisms of plant acclimation to stress conditions contributing to obtain resilient crops. Also, it is essential to develop new methods in plant research that permit to better characterize non-destructively plant traits of interest. In this sense, the advance in plant phenotyping research by high throughput systems is key to overcome these challenges, while its verification in the field may clear doubts on its feasibility. To this aim, this thesis focused on wheat and secondarily on maize as study species as they make up the major staple crops worldwide. A large panoply of phenotyping methods was employed in these works, ranging from RGB and hyperspectral sensing to metabolomic characterization, besides of other more conventional traits. All research was performed with trials grown in the field and diverse stressor conditions representative of major constrains for plant growth and production were studied: water stress, nitrogen deficiency and disease stress. Our results demonstrated the great potential of leave-to-canopy color traits captured by RGB sensors for in-field phenotyping, as they were accurate and robust indicators of grain yield in wheat and maize under disease and nitrogen deficiency conditions and of leaf nitrogen concentration in maize. On the other hand, the characterization of the metabolome of wheat tissues contributed to elucidate the metabolic mechanisms triggered by water stress and their relationship with high yielding performance, providing some potential biomarkers for higher yields and stress adaptation. Spectroscopic studies in wheat highlighted that leaf dorsoventrality may affect more than water stress on the reflected spectrum and consequently the performance of the multispectral/hyperspectral approaches to assess yield or any other relevant phenotypic trait. Anatomy, pigments and water changes were responsible of reflectance differences and the existence of leaf-side-specific responses were discussed. Finally, the use of spectroscopy for the estimation of the metabolite profiles of wheat organs showed promising for many metabolites which could pave the way for a new generation phenotyping. We concluded that future phenotyping may benefit from these findings in both the low-cost and straightforward methods and the more complex and frontier technologies.[cat] Els efectes del canvi climàtic sobre els agro-ecosistemes i l’increment de la població mundial posa en risc la seguretat alimentària i l’estabilitat dels ecosistemes. Actualment, satisfer les demandes de producció d’aliments sota l’escenari del canvi climàtic és el repte central a la Biologia Vegetal. Per això, és indispensable entendre els mecanismes subjacents de l’aclimatació a l’estrès que permeten obtenir cultius resilients. També és precís desenvolupar nou mètodes de recerca que permetin caracteritzar de manera no destructiva els trets d’interès. L’avenç del fenotipat vegetal amb sistemes d’alt rendiment és clau per abordar aquests reptes. La present tesi s’enfoca en el blat i secundàriament en el panís com a espècies d’estudi ja que constitueixen els cultius bàsics arreu del món. Un ampli ventall de mètodes de fenotipat s’han utilitzat, des sensors RGB a híper-espectrals fins a la caracterització metabolòmica. La recerca s’ha dut a terme en assajos de camp i s’han avaluat diversos tipus d’estrès representatius de les majors limitacions pel creixement i producció vegetal: estrès hídric i biòtic i deficiència de nitrogen. Els resultats demostraren el gran potencial dels trets del color RGB (des de la planta a la capçada) pel fenotipat de camp, ja que foren indicadors precisos del rendiment a blat i panís sota condicions de malaltia i deficiència de nitrogen i de la concentració de nitrogen foliar a panís. La caracterització metabolòmica de teixits de blat contribuí a esbrinar els processos metabòlics endegats per l’estrès hídric i la seva relació amb comportament genotípic, proporcionant bio-marcadors potencials per rendiments més alts i l’adaptació a l’estrès. Estudis espectroscòpics en blat van demostrar que la dorsoventralitat pot afectar més que l’estrès hídric sobre l’espectre de reflectància i consegüentment sobre el comportament de les aproximacions multi/híper-espectrals per avaluar el rendiment i d’altres trets fenotípics com anatòmics i contingut de pigments. Finalment, l’ús de l’espectroscòpia per l’estimació del contingut metabòlic als teixits de blat resulta prometedor per molts metabòlits, la qual cosa obre les portes per a un fenotipat de nova generació. El fenotipat pot beneficiar-se d’aquestes troballes, tant en els mètodes de baix cost com de les tecnologies més sofisticades i d’avantguarda

The nitrogen cost of photosynthesis

Global food security depends on three main cereal crops (wheat, rice and maize) achieving and maintaining high yields, as well as increasing their future yields. Fundamental to the production of this biomass is photosynthesis. The process of photosynthesis involves a large number of proteins that together account for the majority of the nitrogen in leaves. As large amounts of nitrogen are removed in the harvested grain, this needs to be replaced either from synthetic fertilizer or biological nitrogen fixation. Knowledge about photosynthetic properties of leaves in natural ecosystems is also important, particularly when we consider the potential impacts of climate change. While the relationship between nitrogen and photosynthetic capacity of a leaf differs between species, leaf nitrogen content provides a useful way to incorporate photosynthesis into models of ecosystems and the terrestrial biosphere. This review provides a generalized nitrogen budget for a C3 leaf cell and discusses the potential for improving photosynthesis from a nitrogen perspective.This work was supported by the Australian Research Council Centre of Excellence for Translational Photosynthesis (CE140100015) and the Grains Research Development Corporation (ANU00025)

Breeding for increased nitrogen-use efficiency: a review for wheat (T. aestivum L.)

Nitrogen fertilizer is the most used nutrient source in modern agriculture and represents significant environmental and production costs. In the meantime, the demand for grain increases and production per area has to increase as new cultivated areas are scarce. In this context, breeding for an efficient use of nitrogen became a major objective. In wheat, nitrogen is required to maintain a photosynthetically active canopy ensuring grain yield and to produce grain storage proteins that are generally needed to maintain a high end-use quality. This review presents current knowledge of physiological, metabolic and genetic factors influencing nitrogen uptake and utilization in the context of different nitrogen management systems. This includes the role of root system and its interactions with microorganisms, nitrate assimilation and its relationship with photosynthesis as postanthesis remobilization and nitrogen partitioning. Regarding nitrogen-use efficiency complexity, several physiological avenues for increasing it were discussed and their phenotyping methods were reviewed. Phenotypic and molecular breeding strategies were also reviewed and discussed regarding nitrogen regimes and genetic diversity

Plasticity of Sorghum Biomass and Inflorescence Traits in Response to Nitrogen Application

Nitrogen is an essential nutrient required for growth and development in plants. Insufficient nitrogen availability can reduce vegetative growth and grain yield. However, nitrogen is a costly input for farmers, is energy intensive to manufacture, and runoff of excess nitrogen fertilizer impacts water quality. Compared to its close relative, maize, sorghum has much greater resilience to nitrogen and water deficit, and heat stress, allowing sorghum to be grown with fewer inputs and on marginal land. Variation in total biomass accumulation and grain yield between sorghum accessions, as well as between nitrogen conditions, can be largely explained by differences in vegetative growth and inflorescence architecture traits. Previous genome-wide association studies (GWAS) in sorghum have identified genetic markers associated with genes known to play roles in controlling growth and development. However, these studies have typically been conducted using field trials with “optimal” nitrogen application conditions. A set of 345 diverse inbred lines from the Sorghum Association Panel (SAP) were grown under both standard nitrogen application (N+) and no nitrogen application (N-) treatments, and a range of biomass and inflorescence-related traits were phenotyped, including plant height, lower and upper stem diameter, rachis length, lower and upper rachis diameter, and primary branch number. Stem volume, an approximation of biomass, was calculated from the directly measured traits. Stem volume was, on average, 10.48% higher for genotypes in nitrogen fertilized blocks, than for genetically identical plants in no nitrogen application blocks. Within individual treatment conditions, between 58.1% and 90.7% of the total variation for the measured and calculated traits could be explained by genetic factors. Genome-wide association studies were conducted to identify genetic markers associated with these traits in order to better understand the genetic factors involved in nitrogen stress response for potential use in breeding improved sorghum varieties. Co-Advisers: Brandi Sigmon and James C. Schanbl