Germination and Growth of Rough Lemon (Citrus jambhiri Lush.) Seedlings under Protected Environment

Production of disease-free plants is necessary for a healthy future for the citrus industry. Therefore, a study was designed to compare growth of direct-sown and transplanted rough lemon seedlings under controlled conditions. Rough lemon rootstock seedlings were grown under screen-house, shade-net house, glasshouse, and open field conditions. Seeds were planted in seed beds, propagation trays and black polythene bags. Germination was significantly higher (94.30%) in propagation trays under shade-net house except that in screen-house. Minimum germination (62.45%) was recorded in open-field seed-beds. Seedling height, stem diameter, leaf number and leaf area was found to be maximum (i.e., 55.26cm, 0.63cm, 33.43 and 24.75cm2respectively) in direct-sown seeds in polybags under screen-house which were transferred to glasshouse during winter. Minimum values observed were 41.33cm, 0.44cm, 18.29 and 15.47cm2, respectively, in conventionally raised seedlings. On the basis of our study, it is concluded that rough lemon nursery is best raised in polybags under screen-house or glasshouse conditions

Improving Nitrogen and Phosphorus Efficiency for Optimal Plant Growth and Yield

Nitrogen (N) and phosphorus (P) are the most important nutrients for crop production. The N contributes to the structural component, generic, and metabolic compounds in a plant cell. N is mainly an essential part of chlorophyll, the compound in the plants that is responsible for photosynthesis process. The plant can get its available nitrogen from the soil by mineralizing organic materials, fixed-N by bacteria, and nitrogen can be released from plant as residue decay. Soil minerals do not release an enough amount of nitrogen to support plant; therefore, fertilizing is necessary for high production. Phosphorous contributes in the complex of the nucleic acid structure of plants. The nucleic acid is essential in protein synthesis regulation; therefore, P is important in cell division and development of new plant tissue. P is one of the 17 essential nutrients for plant growth and related to complex energy transformations in the plant. In the past, growth in production and productivity of crops relied heavily on high-dose application of N and P fertilizers. However, continue adding those chemical fertilizers over time has bad results in diminishing returns regarding no improvement in crop productivity. Applying high doses of chemical fertilizers is a major factor in the climate change in terms of nitrous oxide gas as one of the greenhouse gas and eutrophication that happens because of P pollution in water streams. This chapter speaks about N and P use efficiency and how they are necessary for plant and environment

A Review of Methods to Improve Nitrogen Use Efficiency in Agriculture

Management of nitrogen (N) is a challenging task and several methods individually and in combination are in use to manage its efficiency. However, nitrogen use efficiency (NUE) has not been improved to a level, only 33%, as predicted by the researchers while developing nitrogen management tools and methods. The primary objective of this review article is to evaluate methods and tools available to manage nitrogen. Several methods, soil testing, plant tissue testing, spectral response, fertilizer placement and timing and vegetative indexes (leaf area index, and NDVI) through drones, handheld sensors, and satellite imagery were reviewed on the subject of user-friendly and effectiveness towards NUE. No single method was found sufficient to counter the nitrogen loss. Some methods were found time consuming and unsynchronized with N uptake behavior of particular crop, for example, plant tissue testing. Use of precision agriculture tools, such as GreenSeeker, Holland Crop Circle, drone, and satellite imagery, were found better compared to conventional methods such as soil testing, but these tools can only be used when the crop is up. Therefore, N management is possible only through inseason N application methods. When 70% of the applied nitrogen is used by the crops within 25–30 days after planting, for example, corn and potatoes, it is required to apply major N rates through inseason approach and some N at planting using soil test reports. In conclusion, this article strongly advocates using two or more methods in combination when managing N

A review of potassium significance and management approaches in potato production under sandy soils

Abstract This review focuses on the critical role of potassium (K) in potato cultivation, addressing its essential functions in plant metabolism and the challenges in managing soil K levels, specifically under sandy soils. The K use efficiency is higher in potatoes, with the maximum potential up to 55%, compared to cereals at 19%. Potatoes require high quantities of K, especially in well‐drained sandy soils, to maximise growth and yield. Because K is a highly leaching‐prone nutrient in these soils, its deficiencies could affect plant health, metabolism (K is required to activate more than 60 enzymes) and productivity. Optimal potato growth necessitates maintaining 1.8% K in the tubers, corresponding to a need of 0.22 kg K2O ac−1 for a substantial yield. The review article highlights the significant use of potash fertilisers in the United States, with an average consumption of 4.43 million metric tons between 2010 and 2021, underscoring the importance of K in agricultural practices. The paper also highlights the difference in K requirement and removal among different potato varieties that require the maximum amount in processing types. This manuscript discusses K's management schemes through soil testing, plant tissue analysis and artificial intelligence. The integration of various machine‐learning methods could offer promising prospects for predicting K response in potatoes, aiming to improve nutrient management and sustainable crop production. By synthesising current knowledge and advancements in K fertilisation techniques, this paper provides insights into overcoming the challenges of K management in potato cultivation, ultimately contributing to increased productivity and improved crop quality

A Case Study of Potential Reasons of Increased Soil Phosphorus Levels in the Northeast United States

Recent phosphorus (P) pollution in the United States, mainly in Maine, has raised some severe concerns over the use of P fertilizer application rates in agriculture. Phosphorus is the second most limiting nutrient after nitrogen and has damaging impacts on crop yield if found to be deficient. Therefore, farmers tend to apply more P than is required to satisfy any P loss after its application at planting. Several important questions were raised in this study to improve P efficiency and reduce its pollution. The objective of this study was to find potential reasons for P pollution in water bodies despite a decrease in potato acreage. Historically, the potato was found to be responsible for P water contamination due to its high P sensitivity and low P removal (25–30 kg ha−1) from the soil. Despite University of Maine recommended rate of 56 kg ha−1 P, if soil tests reveal that P is below 50 kg ha−1, growers tend to apply P fertilizer at the rate of 182 kg ha−1 to compensate for any loss. The second key reason for excessive P application is its tendency to get fixed by aluminum (Al) in the soil. Soil sampling data from UMaine Soil Testing Laboratory confirmed that in Maine reactive Al levels have remained high over the last ten years and are increasing further. Likewise, P application to non-responsive sites, soil variability, pH change, and soil testing methods were found to be other possible reasons that might have led to increases in soil P levels resulting in P erosion to water streams

Bacterial biostimulants for climate smart agriculture practices: Mode of action, effect on plant growth and roadmap for commercial products

Abstract Amidst the global food shortage and the global climate change challenge, there is an urgent need to double food production by 2050. However, the modern crop production methods, including the use of fertilizers and pesticides, have adverse environmental consequences, exacerbating the climate crisis. To address this challenge, a transition to sustainable agriculture is imperative that can harmonize the issue. Biostimulants offer an eco‐friendly solution, especially bacterial biostimulants centred on plant growth‐promoting rhizobacteria (PGPRs). These biostimulants hold the promise of offering environmentally sustainable solutions to enhance crop productivity. The adoption of PGPR‐based biostimulants in agriculture has gained significant momentum in agricultural research. PGPRs enhance plant growth through multifaceted mechanisms. This review delves into the various modes of action employed by PGPRs to improve plant growth, including their impact on nutrient availability (such as nitrogen fixation and mineral solubilization) and stress mitigation. In addition, the practical implication of PGPR strains in field research has been discussed extensively. Besides, the review outlines the roadmap for commercializing PGPR‐based biostimulants and discusses the associated challenges and limitations. A balanced perspective on the practical implementation of PGPRs in modern agriculture is presented. Exploration of future strategies and directions rounds out the review, emphasizing the necessity of a comprehensive approach to address research gaps and unlock the full potential of PGPR‐based biostimulants for sustainable agriculture. In conclusion, this review underscores the applicability of PGPR‐based biostimulants as an innovative solution to address the current food crisis in the context of climate change

Potato Phosphorus Response in Soils with High Value of Phosphorus

Phosphorus (P) is an element that is potatoes require in large amounts. Soil pH is a crucial factor impacting phosphorus availability in potato production. This study was conducted to evaluate the influence of P application rates on the P efficiency for tuber yield, specific gravity, and P uptake. Additionally, the relationship between soil pH and total potato tuber yield was determined. Six rates of P fertilization (0–280 kg P ha−1) were applied at twelve different sites across Northern Maine. Yield parameters were not responsive to P application rates. However, regression analysis showed that soil pH was significantly correlated with total potato tuber yield(R2 = 0.38). Sites with soil pH values < 6 had total tuber yields, marketable tuber yields, tuber numbers per plant, and total tuber mean weights that were all higher than these same parameters at sites with soil pH ≥ 6. All sites with soil pH< 6 showed a highly correlated relationship between P uptake and petiole dry weight (R2 = 0.76). The P application rate of 56 kg P ha−1 was the best at sites with a soil pH < 6, but 0–56 kg P ha−1 was the best at sites with soil pH ≥ 6

Predicting Phosphorus and Potato Yield Using Active and Passive Sensors

Applications of remote sensing are important in improving potato production through the broader adoption of precision agriculture. This technology could be useful in decreasing the potential contamination of soil and water due to the over-fertilization of agriculture crops. The objective of this study was to assess the utility of active sensors (Crop Circle™, Holland Scientific, Inc., Lincoln, NE, USA and GreenSeeker™, Trimble Navigation Limited, Sunnyvale, CA, USA) and passive sensors (multispectral imaging with Unmanned Arial Vehicles (UAVs)) to predict total potato yield and phosphorus (P) uptake. The experimental design was a randomized complete block with four replications and six P treatments, ranging from 0 to 280 kg P ha−1, as triple superphosphate (46% P2O5). Vegetation indices (VIs) and plant pigment levels were calculated at various time points during the potato growth cycle, correlated with total potato yields and P uptake by the stepwise fitting of multiple linear regression models. Data generated by Crop Circle™ and GreenSeeker™ had a low predictive value of potato yields, especially early in the season. Crop Circle™ performed better than GreenSeeker™ in predicting plant P uptake. In contrast, the passive sensor data provided good estimates of total yields early in the season but had a poor correlation with P uptake. The combined use of active and passive sensors presents an opportunity for better P management in potatoes

Sulfur source effects on soil, vegetation indices, biomass, and uptake in potato

Abstract Sulfur (S) is necessary for amino acid production, disease resistance, protein synthesis, and nitrogen assimilation in plants. We tested the performance of three S sources (magnesium sulfate [EPTOP], gypsum, and ammonium sulfate [AS]) at two different rates (45 and 90 kg S ha−1) on soil S availability, vegetative indices (VIs), above‐ and belowground biomass (BGB), and potato (Solanum tuberosum L.) S uptake. For VIs such as normalized difference vegetative index, normalized difference red‐edge index, and chlorophyll content, the maximum values were reported when gypsum and EPTOP were applied compared to AS. These differences were decreased later in the season. Significant interaction effects were reported among sites, sampling events, and sites and S sources for aboveground biomass (AGB). Similar trends were reported for the BGB, where the significant interaction effect was reported among the S sources and sampling event and S sources and sites. The AGB S uptake was affected due to the sites and sampling event. However, BGB S uptake was influenced by the interactive effect of S sources, sites, and sampling events. The VIs did not have a significant association between soil S concentration and AGB S uptake. It was found that the field history had a notable effect on the crop responses to variable S sources. In conclusion, applying S rates and sources has distinct responses, which depend on soil history and chemical properties, and that should be considered when making choices for S application in potatoes

Effects of Planting Pre-Germinated Buds on Stand Establishment in Sugarcane

Sugarcane (a complex hybrid of Saccharum spp.) is propagated vegetatively by using stem pieces of mature cane with healthy buds. Abiotic and biotic stress may cause pre-germination of these buds, which may have an impact on both emergence and plant cane stand establishment. There is very limited information available in the literature. A greenhouse study was conducted with single-budded seed pieces of three levels of bud germination (ungerminated buds, Pop-eyes, and Lalas) from three different cultivars (CP 96-1252, CPCL 05-1201, and CPCL 02-0926) planted in pots and repeated over time. Data on growth parameters (tiller count, primary shoot height, SPAD, and dry biomass of shoots and roots) at early growth showed that Lalas produced more tillers and higher shoot dry biomass than Pop-eyes and ungerminated buds. Both Lalas and Pop-eyes produced higher root dry biomass than ungerminated buds in one of the two experiments. The cultivar had a significant effect on primary shoot height and SPAD. A small plot field experiment was conducted with cultivar CP 96-1252 to validate the results of greenhouse experiments, and similar results were reported for tiller count. The results indicate that pre-germinated buds may have a neutral or positive effect on early sugarcane growth and establishment. Further on-farm research needs to be conducted to confirm these results before using pre-germinated buds as a potential seed source for the late season planting of sugarcane