Morphophysiological Responses of Oat (Avena sativa L.) Genotypes from Pakistan’s Semiarid Regions to Salt Stress

Soil salinity is a major constraint to modern agriculture, with around 20% of the previously irrigated area becoming salt affected. Identifying suitable salt stress-tolerant genotypes based on their agronomic and physiological traits remains a herculean challenge in forage-type Oat (Avena sativa L.) breeding. The present study was designed to investigate the response of oat crop plants against the salt (NaCl) stress in Mardan, Pakistan. The experiment was carried out in complete randomized design (CRD) with two factors trail comprising of the performance of four different genotypes of oat (NARC oat, PARC oat, Green Gold and Islamabad oat) in response to four levels of saline stress (0, 25, 50 and 75 mmol L-1 NaCl). Plant growth and physiological parameters including germination (G, %); fresh shoot weight (FSW, g); fresh root weight (FRW, g); chlorophyll-a, chlorophyll-b, total chlorophyll, and total carotenoids were analyzed for identifying salt tolerance. Germination (%) of oat genotypes was negatively affected by higher salt stress. Mean values showed that maximum germination (57.5%) was recorded for control while minimum germination (48.75%) was recorded for 25 mmol L-1 NaCl and that maximum germination (58%) was recorded for PARC oat. The root and shoot fresh weight of all genotypes declined with increasing salt stress, while NARC and Green Gold oat showed considerably higher values than the other genotypes. Although chlorophyll and carotenoids were found to be negatively affected by increasing salt concentrations, NARC and Green Gold oat genotypes performed considerably better at 75 mmol L-1 NaCl when compared to the other genotypes. Based on the mean shoot dry weight ratio ± one standard error, the four Oat genotypes were categorized as salt-tolerant (Green Gold), moderately tolerant (PARC and NARC), and salt-sensitive (Islamabad). The more salt-tolerant genotype (Green Gold) demonstrated relatively high salinity tolerance and may be useful for developing high-yielding oat hybrids in future breeding programs under salt stress conditions

Short-term effects of phosphate fertilizer enriched with low molecular weight organic acids on phosphorus release kinetic and availability under calcareous conditions in arid region

Phosphate reactions and retention in the soil are of paramount importance from the perspective of plant nutrition and fertilizer use efficiency. The objective of this work was to investigate the effect of some low molecular weight organic acids (LMWOAs) on phosphorus release kinetic and its availability in calcareous soil. Experiments were conducted in laboratory. Soil-limestone mixtures were prepared to achieve highly calcareous samples (i.e. 50% CaCO3). The prepared samples were mixed thoroughly with phosphate fertilizers i.e. Triple super phosphate (TSP) and Monoammonium Phosphate (MAP) and watered with distilled water only (CK), with citric acid solution (CA) and with oxalic acid solution (OA). The treatments were arranged in a CRD with three replications and incubated at 25 ± 2°C and 80% soil moisture for a period of 960 h. The parabolic model was used for describing the decrease in P with time. As a result, all treatments showed a significant decrease in available P with time. Using LMWOAs showed important results and combination of phosphate fertilizers with both LMWOAs solutions exerted a very favorable effect on P availability in soil. The parabolic diffusion equation used was fitted well to experimental data. Addition of LMWOAs decreased loss in extractability of P with increasing soil available phosphorus fraction. Moreover, treatments irrigated by LMWOAs solutions released a lot of phosphorus compared to untreated treatments. &nbsp

Partial Substitution of Chemical Fertilizers with Organic Supplements Increased Wheat Productivity and Profitability under Limited and Assured Irrigation Regimes

Crop wastes could be applied in conjunction with synthetic fertilizers to satisfy crop nutritional needs and enhance soil fertility. A field experiment was carried out during winter 2019–2020 at the AMK Research Farm (Palatoo) Mardan, KPK (Pakistan) to investigate the combined effect of phosphorous (PS) and organic sources (OSs) on wheat productivity under different irrigation regimes. The experimental factors were: two irrigation regimes (limited and full irrigation), three inorganic sources of phosphorus (triple super phosphate (TSP), single super phosphate (SSP) and di-ammonium phosphate (DAP)) applied at 90 kg ha−1, and three organic amendments (farmyard manure (FYM), mung bean residue (MBR), and canola residue (CR)) applied at a rate of 10 t ha−1. A control plot (no phosphorus or organic supply) was included. A randomized complete block design (RCBD) with three replications was adopted. Among the fertilization strategies, SSP + FYM outperformed all other P fertilizers combined with legume or nonlegume residues in terms of grains per spike−1 (52), thousand-grain weight (41.6 g), biological yield (9.7 t ha−1), and grain yield (4 t ha−1). Under full irrigation, improved yield, yield components, and profits were obtained compared to the limited irrigation regime. Three clusters were obtained after applying an Agglomerative Hierarchical Clustering (AHC), and Principal Component Analysis (PCA) conferred the positive effects of inorganic P with FYM on the wheat yield and its related parameters. This study indicated that the productivity of wheat under the SSP + FYM fertilization strategy was found to be more economical with respect to the benefit–cost ratio (BCR). The combined application of SSP + FYM was more profitable in terms of a higher BCR (3.25) than other treatments under the full irrigation regime

Integrated use of phosphorus fertilizer and farmyard manure improves wheat productivity by improving soil quality and P availability in calcareous soil under subhumid conditions

IntroductionLow soil fertility and high fertilizer costs are constraints to wheat production, which may be resolved with integrating fertilizer phosphorus (P) and farm-yard manure (FYM). Study objectives were to evaluate P source impacts on soil, P efficiency, and wheat growth in a calcareous soil.MethodsTreatments included P fertilizer (0, 17, 26, or 39 kg P ha-1) and/or FYM (0 or 10 T ha-1) in a: 1) incubation experiment and 2) wheat (Triticum aestivum spp.) field experiment.Results and DiscussionSoil organic matter increased (30-72%) linearly for both fertilizer and FYM, whereas pH decreased (0.1-0.3 units) with fertilizer only. Addition of fertilizer and FYM increased plant available P (AB-DTPA extractable soil P) an average of 0.5 mg P kg-1 soil week-1 with incubation. The initial increase was 1-9 mg P kg-1, with further increase after 84 d of ~3-17 mg P kg-1. There was also a significant increase of available P in the soil supporting plants in the field study, although the magnitude of the increase was only 2 mg kg-1 at most for the highest fertilizer rate + FYM. Grain (66 to 119%) and straw (25-65%) yield increased significantly, peaking at 26 kg P ha-1 + FYM. The P Absorption Efficiency (PAE), P Balance (PB), and P Uptake (PU) increased linearly with P rate, with the highest levels at the highest P rate. The P Use Efficiency (PUE) was highest at the lowest rates of P, with general decreases with increasing P, although not consistently. Principal component analysis revealed that 94.34 % of the total variance was accounted for with PC1 (84.04 %) and PC2 (10.33 %), with grain straw yield significantly correlated to SOM, PU, and PAE. Regression analysis showed highly significant correlation of PB with P-input (R2= 0.99), plant available P (R2= 0.85), and PU (R2= 0.80). The combination of FYM at the rate of 10 T ha-1 and fertilizer P at 26 kg P ha-1 was found as the optimum dose that significantly increased yield. It is concluded that FYM concoction with fertilizer-P not only improved SOM and residual soil P, but also enhanced wheat yields with reasonable P efficiency

Partial Substitution of Chemical Fertilizers with Organic Supplements Increased Wheat Productivity and Profitability under Limited and Assured Irrigation Regimes

Crop wastes could be applied in conjunction with synthetic fertilizers to satisfy crop nutritional needs and enhance soil fertility. A field experiment was carried out during winter 2019–2020 at the AMK Research Farm (Palatoo) Mardan, KPK (Pakistan) to investigate the combined effect of phosphorous (PS) and organic sources (OSs) on wheat productivity under different irrigation regimes. The experimental factors were: two irrigation regimes (limited and full irrigation), three inorganic sources of phosphorus (triple super phosphate (TSP), single super phosphate (SSP) and di-ammonium phosphate (DAP)) applied at 90 kg ha−1, and three organic amendments (farmyard manure (FYM), mung bean residue (MBR), and canola residue (CR)) applied at a rate of 10 t ha−1. A control plot (no phosphorus or organic supply) was included. A randomized complete block design (RCBD) with three replications was adopted. Among the fertilization strategies, SSP + FYM outperformed all other P fertilizers combined with legume or nonlegume residues in terms of grains per spike−1 (52), thousand-grain weight (41.6 g), biological yield (9.7 t ha−1), and grain yield (4 t ha−1). Under full irrigation, improved yield, yield components, and profits were obtained compared to the limited irrigation regime. Three clusters were obtained after applying an Agglomerative Hierarchical Clustering (AHC), and Principal Component Analysis (PCA) conferred the positive effects of inorganic P with FYM on the wheat yield and its related parameters. This study indicated that the productivity of wheat under the SSP + FYM fertilization strategy was found to be more economical with respect to the benefit–cost ratio (BCR). The combined application of SSP + FYM was more profitable in terms of a higher BCR (3.25) than other treatments under the full irrigation regime

Canola Seed Priming and Its Effect on Gas Exchange, Chlorophyll Photobleaching, and Enzymatic Activities in Response to Salt Stress

Canola is the second-largest oil seed crop in the world, providing oil mainly composed of long-chain fatty acids (C14 to C20). When mixed with fossil-diesel, canola-based biofuel can be used in passenger vehicles, trucks, or even in aviation. Canola is the most productive type of biofuel due to its oil’s long-chain and unbranched fatty acid composition, which makes it more fluid. However, canola yields are constrained by drought and salinity that can aggravate climate change, resulting in negative consequences. Therefore, it is becoming necessary for studies that involved the canola salt-tolerant genotypes to consider soil salinization by use of saline soil or salinized soil by a non-efficient irrigation method. This study was carried out to assess the effects of salinity on seed germination and the effect of CaCl2 (ψs = −1.2 MPa) on the promotion of regenerated plant memory when a new cycle of stress occurs. Our experiment shows that salt-stressed canola plants resulted in a high reduction in chlorophylls and carotenoids, with a high impact on gas exchange and a reduction in the efficiency of the chloroplast electron chain transporter, producing the negative effect of reduced molecules that affect the membrane integrity. However, canola seed priming could produce a memory in the regenerated plants when the second round of salt stress was applied. This research concludes that canola genotypes appear to have a tolerance mechanism against salt stress which could be an important trait for developing high-yielding canola varieties in future breeding programs under salt stress conditions

Developmental, Phytochemical and Enzymatic Changes in Pot Marigold (<i>Calendula officinalis</i> L.) cvs. Hybrid and French with Salicylic Acid (SA) and Polyamine Spermidine (SP) Foliar Spray

Marigolds (Calendula officinalis L.) are valuable in ornamentation, human food, and other uses; to enhance productivity, plant growth regulators produce stimulatory effects, including salicylic acid (SA) and spermidine (SP), but there is a lack of scientific evidence about such effects in marigolds. The study assessed, under greenhouse conditions, changes in physico-chemical parameters, enzymatic activity, and bioactive compounds of marigold cvs. Hybrid and French marigolds were sprayed of SA (1 and 2 mM) and SP (2 and 3 mM) and compared to control (pure water). The SA at 2 mM improved leaf length (8.20 cm), flower height and diameter (5.32, 8.28 cm), flower fresh and dry weight (14.30, 1.5 g), and the maximum number of flower petals (55) in ‘Hybrid’. Similarly, 2 mM SA gave the maximum number of leaves (40.71) and stem thickness (5.76 mm) in ‘French’, but 3 mM SP promoted the maximum plant height in ‘Hybrid’. Superoxide dismutase, peroxidase, and catalase activities increased in ‘Hybrid’ with 2 mM SA; with this SA dose, ‘Hybrid’ had higher contents of total phenolic compounds (68.34 mg GAE g−1), antioxidants (77%), carotenoids (110 mg 100 g−1), and flavonoids (67.5 mg RE g−1) than the control. The best dose for improving growth in both marigold varieties was 2 mM SA

Activated Biochar Is an Effective Technique for Arsenic Removal from Contaminated Drinking Water in Pakistan

Arsenic (As), the silent poison, is a widespread environmental pollutant which finds its way into drinking water supplies from natural or man-made sources and affects over 200 million people worldwide, including in Pakistan. It has been demonstrated that As causes serious health complications as well as social and economic losses. A quick, cost-effective, and simple method for efficiently filtering As from drinking water is urgently needed. The present study evaluates the ability of chemical treatment solutions to activate the sorption capacity of biochar derived from cotton stalks. The surface characteristics of CSB (cotton stalk biochar), HN-CSB (treated with nitric acid: HNO3), and Na-CSB (treated with sodium hydroxide: NaOH) were investigated for their As sorption capacities and efficiency in removing As from contaminated drinking water. The chemical modification of biochar significantly increased the surface area and pore volume of CSB, with a maximum observed in HN-CSB (three times higher than CSB). Fourier-transform infrared spectroscopy (FTIR) analysis revealed several functional groups (OH−, −COOH, C=O, N-H) on CSB, though the chemical modification of biochar creates new functional groups on its surface. Results showed that the maximum sorption capacity of CSB was (q = 90 µg g−1), of Na-CSB was (q = 124 µg g−1) and of HN-CSB was (q = 140 µg g−1) at an initial As concentration of 200 µg L−1, an adsorbent dose of 1 g L−1, with 4 h of contact time, a pH of 6 and a temperature of 25 ʰC. However, As removal was found to be 45–88% for CSB, 62–94% for Na-CSB and 67–95% for HN-CSB across all As concentrations. An isotherm model showed that As sorption results were best fitted to the Langmuir isotherm model in the case of CSB (Qmax = 103 µg g−1, R2 = 0.993), Na-CSB (Qmax = 151 µg g−1, R2 = 0.991), and HN-CSB (Qmax = 157 µg g−1, R2 = 0.949). The development of the largest surface area, a porous structure, and new functional groups on the surface of HN-CSB proved to be an effective treatment for As removal from contaminated drinking water. Both HN-CSB and Na-CSB are clearly cost-effective adsorbents under laboratory conditions, but HN-CSB is cheaper and more efficient in As removal than Na-CSB, allowing it to be used as a powerful and promising adsorbent for the removal of pollutants like Arsenic from aqueous solution

Pyramiding of Four Broad Spectrum Bacterial Blight Resistance Genes in Cross Breeds of Basmati Rice

Pyramiding of major resistance (R) genes through marker-assisted selection (MAS) is a useful way to attain durable and broad-spectrum resistance against Xanthomonas oryzae pv. oryzae pathogen, the causal agent of bacterial blight (BB) disease in rice (Oryza sativa L.). The present study was designed to pyramid four broad spectrum BB-R genes (Xa4, xa5, xa13 and Xa21) in the background of Basmati-385, an indica rice cultivar with much sought-after qualitative and quantitative grain traits. The cultivar, however, is susceptible to BB and was therefore, crossed with IRBB59 which possesses R genes xa5, xa13 and Xa21, to attain broad and durable resistance. A total of 19 F1 plants were obtained, some of which were backcrossed with Basmati-385 and large number of BC1F1 plants were obtained. In BC1F2 generation, 31 phenotypically superior genotypes having morphological features of Basmati-385, were selected and advanced up to BC1F6 population. Sequence-tagged site (STS)-based MAS was carried out and phenotypic selection was made in each successive generation. In BC1F6 population, potentially homozygous recombinant inbred lines (RILs) from each line were selected and evaluated on the bases of STS evaluation and resistance to local Xanthomonas oryzae pv. oryzae (Xoo) isolates. Line 23 was found pyramided with all four BB-R genes i.e., Xa4, xa5, xa13 and Xa21. Five genotypes including line 8, line 16, line 21, line 27 and line 28 were identified as pyramided with three R genes, Xa4, xa5 and xa13. Pathological study showed that rice lines pyramided with quadruplet or triplet R genes showed the highest level of resistance compared to doublet or singlet R genes. Thus, line 23 with quadruplet, and lines 8, 16, 21, 27, and 28 with triplet R genes, are recommended for replicated yield and resistance trials before release as new rice varieties. Further, traditional breeding coupled with MAS, is a solid way to attain highly effective BB-resistant rice lines with no yield cost

Assessment of the Ecological and Health Risks of Potentially Toxic Metals in Agricultural Soils from the Drosh-Shishi Valley, Pakistan

Soil pollution is a highlighted concern of modern society, particularly in developing countries. The Drosh-Shishi valley, which is a hilly region near Afghanistan with a land area of around 15,000 km2, is situated in the south of Chitral District (Pakistan) and has a population of approximately 450,000. Nowadays, this region is being explored for soil pollution, specifically heavy metals which pose a potential risk to human health. Therefore, our main goal was to investigate possible sources of heavy metals’ spread and to assess the content levels in soil and the associated risks for human. We collected 34 representative samples from transported sediments and 31 from agricultural crops. We analyzed the soil samples for the contents of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn using ICP-OES analyzers. These values were used to obtain the contamination factor (CF) and to estimate the potential health risk caused by heavy metals according to the USEPA dose–response model. Our results suggest that the heavy metal pollution has a geogenic source, but it is also aggregated by chemical fertilizers used in farming. Regarding levels, most of the metals except Pb showed contents above the permissible level, with CF values from moderate to high. Overall, Cu and Ni showed a significant total cancer risk (TCR &gt; 1 × 10−4) in children. Therefore, we conclude that heavy metal pollution is causing a serious threat to humans in this area, and we recommend that authorities should make more efforts in monitoring the heavy metals content in soils to reduce potential health risks