SPAD Meter Research Articles

Effect of summer legume residue incorporation and fertilizer regimes on rice growth, yield, and nutrient uptake

In a field trial at the College Farm, NAU, Navsari (Gujarat), evaluated four main plot treatments (T1: Green gram, T2: Cowpea, T3: Dhaincha, and T4: Fallow), which were grown during the summer with three replications following a randomized block design (RCBD). Green gram and cowpea were incorporated into the soil after harvest, but dhaincha was incorporated at 50% flowering. During Kharif, each main plot was split into six smaller plots with different treatments: W1 was 100% RDF, W2 was 75% RDF, W3 was 50% RDF, W4 was 75% RDF + 25% N from FYM, W5 was 50% RDF + 50% N from FYM, and W6 was no fertilizer. The results of all 24 treatment combinations were repeated three times in a split-plot design. The analysis showed significant growth, yield attributes, grain yield, and straw yield of rice in dhaincha-incorporated plots (T3), fb greengram (T1), and cowpea (T2) plots using 100% RDF, while fallow (T4) with no fertilizer application recorded significantly lower values. SPAD meter readings of rice were higher in W4 (75% RDF + 25% N from FYM), which was at par with W1 in dhaincha-incorporated plots (75% RDF + 25% N from FYM) (W4). However, applying no fertilizer (W6) resulted in lower values. The total uptake of nitrogen and phosphorus in rice was highest when it was grown in dhaincha incorporated (T3), followed by green gram (T1), cowpea (T2) incorporated plots with the usage of 100% RDF (W1) and 75% RDF + 25% N from FYM (W4), and lower values were recorded in fallow + no fertilizer treatment (T4W6). Our study revealed that incorporating summer legumes before planting rice significantly increased plant height, tillers, grain and straw yield, and total uptake. With dhaincha, inclusion has shown a greater advantage.

Data-Driven Prediction of Nitrogen Stress and Crop Yield in a Maize -Wheat Cropping System

The study has attempted to determine leaf-N content in a cropping system consisting of Wheat and Maize using plant sensors like GreenSeeker and SPAD meter (chlorophyll meter) and use machine learning models so that crop yields based on inputs can be predicted of data on nitrogen doses, NDVI values, SPAD values, and leaf N content. The data recorded from field experiments on wheat and maize crop variable fertilized by N (wheat: 0, 30, 60, 90, 120, 150, 180 and 240 kg N/ha; maize: 40, 80, 120, 160, 200, 240 and 300 kg N/ha) were used. A pair plot analysis showed a positive association between leaf N and NDVI, between leaf N and SPAD values, and between NDVI and SPAD values; all these parameters had a positive correlation with N- application rates. For yield prediction, the model calibrated for wheat could validate yield prediction for maize as well. Random Forest and Support Vector Machines showed reproducible performance (consistent) on both datasets (maize and wheat), with accuracies of 85.71% and 100%, respectively, on the original dataset.

Non-Invasive Detection of Nitrogen Deficiency in Cannabis sativa Using Hand-Held Raman Spectroscopy

Proper crop management requires rapid detection methods for abiotic and biotic stresses to ensure plant health and yield. Hemp (Cannabis sativa L.) is an emerging economically and environmentally sustainable crop capable of yielding high biomass. Nitrogen deficiency significantly reduces hemp plant growth, affecting photosynthetic capacity and ultimately decreasing yield. When symptoms of nitrogen deficiency are visible to humans, there is often already lost yield. A real-time, non-destructive detection method, such as Raman spectroscopy, is therefore critical to identify nitrogen deficiency in living hemp plant tissue for fast, precise crop remediation. A two-part experiment was conducted to investigate portable Raman spectroscopy as a viable hemp nitrogen deficiency detection method and to compare the technique’s predictive ability against a handheld SPAD (chlorophyll index) meter. Raman spectra and SPAD readings were used to train separate nitrogen deficiency discrimination models. Raman scans displayed characteristic spectral markers indicative of nitrogen deficiency corresponding to vibrational modes of carotenoids, essential pigments for photosynthesis. The Raman-based model consistently predicted nitrogen deficiency in hemp prior to the onset of visible stress symptoms across both experiments, while SPAD only differentiated nitrogen deficiency in the second experiment when the stress was more pronounced. Our findings add to the repertoire of plant stresses that hand-held Raman spectroscopy can detect by demonstrating the ability to provide assessments of nitrogen deficiency. This method can be implemented at the point of cultivation, allowing for timely interventions and efficient resource use.

Impact of nitrogen and potassium management on growth, nutrient uptake and nutrient use efficiency of rice under semi dry condition

The current study was aimed to search effect of nitrogen doses and time of application on performance of semi dry rice. The field experiment was conducted at College of Agriculture,(V. C. Farm), Mandya, University of Agricultural Sciences, Bengaluru during kharif 2019 and 2020, which comes under Southern Dry Zone of Karnataka (Zone-VI) to study the response of semi dry rice on growth and nutrient use efficiency under two doses of nitrogen and potassium doses (100% RDNK, 125%RDNK) as main treatments and seven time of application as sub treatments.The result revealed that higher SPAD meter reading (37.77) and nutrient uptake (77.90, 27.98 and 24.14 kg ha-1)was seen in 125% RDNK and higher nitrogen and potassium use efficiency was observed in 100%RDNK (49.30, and 98.59 kg kg-1 nutrient applied respectively). Where as in split application, higher SPAD meter reading (38.90), nutrient uptake (81.82, 29.57 and 25.35kg ha-1)and nutrient use efficiency (49.86, 11.33 and 99.73 kg kg-1 nutrient applied respectively) was recorded in N at 4 splits as, 25% each at sowing, early tillering, tillering and panicle initiation, K at 2 splits (50% at basal and 50% at panicle initiation) compared to rest of the application. Hence application of application of 125% RDNK, N at 4 splits as, 25% each at sowing, early tillering, tillering and panicle initiation, K at 2 splits (50% at basal and 50% at panicle initiation) is the appropriate time for rice production Southern Dry Zone of Karnataka.

Proximal canopy sensing of twenty-two bread wheat genotypes for nutritional quality, yield attributes and grain yield under Mediterranean climate

To ensure nutritional security of rapidly increasing population, research interest has revitalized in determining the nutritional quality traits of staple food crops, especially wheat. Besides higher yield potential, research gaps exist regarding nutritional quality assessment of promising wheat genotypes grown under the Mediterranean climate. A field study was conducted to determine the relationship between yield components and quality characteristics of 22 bread wheat genotypes using the SPAD meter, GreenSeeker (NDVI), and CM-1000 chlorophyll meter at different growing stages (Stem elongation, Heading, Anthesis and Milk stage). The recorded findings revealed that G-41 genotype surpassed the rest of bread wheat genotypes by recording the maximum grain yield, whereas G-60 genotype exhibited the highest protein and wet gluten content. Among response variables, SPAD and NDVI values at the heading stage and CM-1000 values at the milk stage were found to be statistically insignificant. According to the correlation and biplot analysis, a significant positive correlation was found between the SPAD values measured for the stem elongation, anthesis and milk stage and yield and quality characteristics. Significant positive correlations were found between the NDVI values at the stem elongation, anthesis, and milk stages and the yield components, and between the CM-1000 value at the heading stage and the grain yield.

Identification of drought tolerant inbred lines and assessment of combining ability in maize (Zea mays L.)

AbstractMaize is an important agricultural crop ensuring food and nutritional security throughout the globe. It is highly sensitive to many of the biotic and abiotic stresses, and among them, drought is the most severe abiotic stress limiting maize production. Climate change tends to worsen this scenario by changing precipitation patterns and decreasing water availability. Hence, the present study was undertaken to identify drought‐tolerant inbred lines under well‐irrigated and managed stress conditions in the field toward developing drought‐resilient maize hybrids. The initial in vitro screening of 65 agronomically elite maize inbred lines was undertaken at 15%, 20%, and 25% polyethylene glycol (PEG) concentrations. Subsequently, the 15 inbreds selected for their promising performance under varying concentrations of PEG were evaluated in the pot (100%, 60%, and 40% of field capacity [FC]) and managed field experiments (moisture stress). Various physiological, biochemical, and yield attributing traits were measured among the inbreds to assess their drought tolerance potential. The analysis of variance in the pot and field experiments indicated significant genotypic differences among the inbreds and genotype × treatment interaction for different traits considered. In the pot experiment, the phenotypic correlation analysis showed a significant positive association of shoot fresh weight with plant height (r = .71), number of leaves (r = .58), relative water content (r = .60), root fresh weight (r = .58), shoot dry weight (r = .60), and SPAD meter readings under (r = .71) moisture stress condition. In the field experiment, the grain yield had a significant positive association with plant height, relative water content, SPAD before stress, ear length, ear girth, kernel rows per ear, kernels per row, and per day productivity under stress. Proline accumulation in inbreds during stress was found to be higher compared to nonstress conditions. The inbred lines CML 505, CML 444, CML 451, CML 504, QM 11408, and MAI 214 were promising for most of the drought tolerance imparting traits. These six inbreds along with four inbreds having low DRI (SKV 50, MAI E2‐163, MAI 16, and MAI E2‐241) were crossed in half diallel manner, and crosses involving low × high or high × low DRI inbreds showed higher grain yield. The current study also revealed the need of combining various physiological and yield attributing traits in drought breeding programmes.

Growth Allometry of Sweet Corn as Influenced by Tillage and Seaweed under Tarai Region of Nagaland

A study was carried out at Crop Research Farm, Department of Agronomy, SAS, Nagaland University, Nagaland, India during kharif (May-September, 2021 and 2022) situated at 25° 45’ 3.68”N latitude and 93° 51’ 29.79” E longitude, to study the influence of tillage and seaweed extract on growth allometry of sweet corn under tarai region of Nagaland. The experiment was conducted in split plot design with two factor treatment and was replicated thrice. Factor one comprised of three tillage practices viz., conventional tillage, minimum tillage and zero tillage in the main plots and factor two included seven treatments consisting of seed priming followed by foliar spray of seaweeds i.e. Kappaphycus alvarezii and Sargassum wightii viz., water spray (control), K-Seaweed sap 5%, K-Seaweed sap 10%, K-Seaweed sap 15%, S-Seaweed sap 5%, S-Seaweed sap 10%, S-Seaweed sap 15%, in the sub-plots at 30, 50 and 70 days after sowing. Results of study revealed that significantly higher stem girth, leaf area, leaf area index, leaf area duration, SPAD meter reading at different intervals were noticed in conventional tillage. When seeds were treated with 10% S-Sap along with 10% S-Sap spray at three different intervals recorded significantly higher stem girth, number of functional leaves plant-1, leaf area, leaf area index, leaf area duration and chlorophyll index readings.

Effect of Irrigation and Nitrogen Management on Potato Growth, Yield, and Water and Nitrogen Use Efficiencies

Irrigation and nitrogen management are crucial for sustainable potato (Solanum tuberosum L.) production. A field experiment was conducted during the 2022 and 2023 growing seasons at Farmington, New Mexico, to evaluate the performance of two chip potato varieties (Lamoka and Waneta) under three irrigation regimes (full irrigation (FI), 20% deficit irrigation (DI) and 40% DI) and seven nitrogen fertilizer rates (0, 60, 115, 170, 220, 280, and 340 kg N/ha). The treatment combinations of irrigation regimes, nitrogen rates, and varieties were arranged in a split–split plot design with three replications as main plot, sub-plot, and sub-sub plot, respectively. The two-year results showed that irrigation regimes had the most significant effect on plant growth, physiology, and tuber yield of the potato varieties. For both Lamoka and Waneta, the plant height and canopy cover were lower under 40% DI than under 20% DI and FI treatments. The SPAD meter values were higher under 40% DI, followed by 20% DI and FI treatments, whereas the stomatal conductance was higher under FI, followed by 20% DI and 40% DI during both growing seasons. Regardless of nitrogen rates and variety, a 20% water-saving irrigation strategy reduced the total tuber yield by 4.5% and 22.1% in the 2022 and 2023 growing seasons, respectively, while the 40% water-saving irrigation strategy reduced total tuber yield by 36.8% and 58.2% in the 2022 and 2023 growing seasons, respectively, as compared to full irrigation. Shifting from full irrigation to 20% DI could save 711.2 to 1036.3 m3/ha of irrigation water. For Lamoka, the highest total tuber yield was obtained with 60 kg N/ha under 20% DI and 220 kg N/ha under FI in 2022 and 2023, respectively. For Waneta, the highest total tuber yield was obtained with 115 kg N/ha under 20% DI and 170 kg N/ha under FI in 2022 and 2023, respectively. Maximum water use efficiency (WUE) was obtained at 60 kg N/ha with 20% DI for both Lamoka and Waneta in 2022, while maximum WUE was obtained at 220 kg N/ha under FI for Lamoka and at 170 kg N/ha for Waneta in the 2023 season. The maximum nitrogen use efficiency (NUE) was achieved with 60 kg N/ha under 20% DI for both varieties during both growing seasons. Thus, for sustainable irrigation and nitrogen management, the application of a 20% deficit irrigation strategy with a lower nitrogen rate (60 to 170 kg N/ha) could be the best option to improve WUE and NUE with minimal tuber yield reduction. Our study suggested that 40% deficit irrigation would not be beneficial as compared to both full irrigation and 20% water-saving irrigation.

A Polysaccharide-Based Integrated Nutrient Management System Enhances the Antioxidant Properties in Origanum dictamnus (Lamiaceae), a Valuable Local Endemic Plant of Crete

Origanum dictamnus L. (Lamiaceae), a local endemic plant of Crete (Greece), creates polysaccharide-containing subcuticular compartments presenting biological activity against phytopathogenic fungi, and, among others, significantly affects the fungal cell wall polysaccharides. This field study introduces a fertilization scheme for O. dictamnus, which was developed and refined to optimize the yield as well as critical herbal quality aspects. Five fertilization schemes were investigated, based on a polysaccharide-based Integrated Nutrient Management (INM), a mixture of conventional inorganic fertilizers (ChF) and two biostimulants (not algae) via foliar and soil application. Plant growth, together with leaf chlorophyll fluorescence and color (SPAD meter, DA meter, Chroma Meter) were determined. The leaf content of chlorophyll, three critical antioxidant compounds (carotenoids, flavonoids, phenols) and nutrients were also assessed. Considering all three antioxidants together, the enhanced efficiency, non-toxic, water-soluble, polysaccharide-based INM by foliar application was the most stimulatory scheme, playing an important role in plant growth and development. The present field study provides, for the first time, baseline fertilization data improving key herbal quality features in O. dictamnus and unravels the attainment of high antioxidant properties. The latter may be exploited in favor of its further utilization as a raw material for tea preparation, medicinal purposes, natural food flavoring and/or food preservative.

Integrated Nutrient Management Boosts Inflorescence Biomass and Antioxidant Profile of Carlina diae (Asteraceae)—An Endangered Local Endemic Plant of Crete with Medicinal and Ornamental Value

Due to the combined climate and biodiversity crisis, the sustainable utilization of phytogenetic resources stands as a one-way alternative, while nutrient management strategies are gaining an increasing role in agriculture. Building on previous studies regarding the Endangered local endemic of Crete (Greece) Carlina diae (Asteraceae), with medicinal and ornamental value, this investigation focused on its pilot cultivation and fertilization (foliar or soil application). Foliar application comprised inorganic fertilization (conventional) or integrated nutrient management (INM). Soil application consisted of conventional inorganic fertilizers, biostimulants, or INM with biostimulants. Above-ground biomass content of nutrients, leaf chlorophyll fluorescence, and color parameters (SPAD meter, DA meter, Chroma Meter) were estimated. The leaf chlorophyll content, three key antioxidant compounds, and nutrient titers were also determined. The fertilization scheme did not influence plant growth and visually perceived quality (leaf color and shape). Notably, foliar INM fertilization increased biomass partitioning to inflorescences (harvestable organs for either medicinal or ornamental purposes) and decreased tissue water content (facilitating processing). Considering all three antioxidants together, INM with biostimulant appeared the optimum scheme, being associated with the highest (carotenoids, phenolics) or the second highest (flavonoid) content. In C. diae, therefore, INM fertilization was optimal for upgrading yield (foliar) and herbal quality in terms of antioxidant profile (INM with biostimulant), which might be embraced as an eco-friendly approach for high-quality yields.

Fight Against Hidden Hunger: Boosting Zinc in Potato through Biofortification in Calcareous Soil of Bihar, India

Micronutrients are often overlooked during fertilizer application, which reduces the content of micronutrients in the soil and crops. The concentration of micronutrients in our meals is decreasing considerably, creating several abnormalities in human body and deterioration of human health, although we consume adequate amount of food, we do not get enough nutrients, which is labeled as hidden hunger. To increase the micronutrient concentration in potato crop, particularly, Zinc, this research was conducted in the Rabi season of 2022 at TCA-Dholi, Dr. RPCAU, Pusa, Bihar. Kufri Khyati, a popular variety in Northern Bihar was given ten treatments and replicated four times, in Randomized Block Design (RBD), experimental design. The concentration of Zn in leaves (95.45 ppm), in tubers (31.50 ppm), SPAD meter reading at 45 DAP, 60 DAP and 75 DAP (49.29, 42.04, 37.11, respectively), yield of tubers (25.17 t ha-1), and B:C ratio (2.97) were maximum in treatment T10 (Zn-EDTA @ 4g litre-1 at 25 and 50 DAP).

Tiller Dynamics, Leaf Area and Spad Meter Ofrice Varieties Influenced by Different Spacing Under Semi-Dry Condition

The field experiment was conducted at College of Agriculture, (V. C. Farm), Mandya, University of Agricultural Sciences, Bengaluru, Karnataka, India during kharif, 2019 and 2020. Soil from experimental site was under sandy loam in texture with 70.50, 15.80 and 13.70% sand, silt and clay, respectively. Soil was alkaline in reaction with pH of 9.02 and low in electrical conductivity (0.37 dS m-1). The fertility status of the soil at experimental site was low in organic carbon (0.39%), available nitrogen (182.12 kg N ha-1) and available potassium (122.32 kg K2O ha-1), however it was high in available phosphorus (78.74kg P2O5ha-1). Results indicated that maximum leaf area, SPAD meter reading and tiller production at different days observed in narrow spacing (20 cm row spacing) compared to wider row spacing (30 cm row spacing). Among the different varieties tested, significantly higher leaf area, SPAD meter reading and tiller production was recorded in KMP- 175 and Rasi compared to other varieties.

Estimation of Chlorophyll Using SPAD meter

A chlorophyll meter measures the greenness of leaves and can indicate the chlorophyll content and N status. Therefore, by using a chlorophyll meter, proxy information related to the leaf N content could be obtained and this would avoid the need of laborious laboratory analysis. Keeping in this view a field experiment was conducted during winter (Rabi) 2019 growing season at the experimental field of JNKVV, Jabalpur to estimate crop nitrogen (N) and chlorophyll content in wheat using SPAD. The treatment comprised of 3 sources of nutrient M1- Inorganic sources (NPK fertilizers), M2- organic sources (FYM, vermicompost, biofertilizers Azotobacter and PSB) and M3- Integrated sources (50% Inorganic + 50% organic) as main treatments and 5 NPK levels S1- control, S2- 100% RDF, S3- 150% RDF, S4- 200% RDF, S5- Based on soil test value for target yield of 6t ha-1 as sub treatments were replicated thrice in a split plot design. The results showed that the correlation (r = 0.94, 0.90, 0.92 and 0.94, respectively) and coefficient of determination (R2 = 0.96, 0.94, 0.83 and 0.94, respectively) was significantly and positively correlated with SPAD and nitrogen concentration in leaf. Similarly significant and positive correlation (r = 0.84, 0.76, 0.78 and 0.71, respectively) found with SPAD and total chlorophyll values. Coefficient of determination (R2) SPAD with chlorophyll and leaf N concentration proved to be significant (R2 = 0.75, 0.76, 0.54 and 0.85, respectively) at different growth stages. It was concluded that SPAD meter are useful for the determination of proxy chlorophyll and total nitrogen content of wheat plant.

Classification of the Nutritional Status of Peach Trees Using Indexes from Hyperspectral Images

This paper presents a procedure for the comparison of two technologies developed to classify peach trees according to their nutritional status. The first technology uses the leaf SPAD-502 meter value to characterize tree classes as indicated by agronomist experts: sound, intermediate, and strong chlorosis trees. It is used as a reference for the second technology, which uses a combination of two multispectral indexes computed from reflectance hyperspectral images. Specifically, R_NDVI = (R800 − R670)/(R800 + R670) and HyperSPAD = (R940/R650) are computed for each leaf pixel. An automated methodology is proposed that sets two optical thresholds (three hyperspectral categories) in view of the outliers according to a normal distribution, together with an iterative optimization of the bounding that determines the best assignment of trees to one of the three SPAD_502 levels of nutritional status, as required for practical agronomical purposes such as fertilization. The Chi 2 distribution is used to confirm the similarity of both nutritional classifications. These results encourage the use of on-board multispectral cameras to monitor the nutritional status of trees and to establish a more efficient fertilization strategy where inputs are applied according to individual status, with the consequent reduction in losses of fertilizers such as nitrogen to the atmosphere, soil, and water resulting from over-application.

Evaluation of Maize Varieties at Seedling Stage under Drought Stress Based on Morpho-physiological and Biochemical Attributes

A hydroponic pot experiment was driven to investigate the improvement of drought tolerance in six maize varieties (e.g. Gold Star, BHM 14, Paloan, Bharti 981, BHM 9, Pioneer) based on morpho-physiological and biochemical characteristics. Six Maize varieties were used as test crops and the experiment was laid out in a completely randomized design (RCBD) with three replications. Drought stress was imposed 14 days after sowing by using the PEG solution. The results revealed that BHM 14 possessed the longest root length (69.33 cm), higher shoot length (42.67 cm), longest total plant height (112.00 cm), highest fresh root weight (3.32 g), high leaf greenness found in BHM 14 measured by SPAD meter in both top and lower leaves, high amount of proline whereas, Paloan produced shortest total plant height (78.50 cm), lowest fresh root weight (1.52 g), lowest proline after 42 days of sowing under stress condition. The maximal photochemical efficiency (Fv/Fm) appeared to measure photosynthesis whereas Pioneer was comparatively higher in stress conditions. The fresh weight of root and shoot was significantly least affected in stress conditions, whereas BHM 14 performed better in stress conditions. On the other hand, varieties had a significant difference in total dry matter of control condition and stress condition. Therefore, it is suggested that BHM 14 showed maximum drought tolerance in respect of growth and morpho-physiological changes under drought conditions.

Impact of SPAD chlorophyll meter based nitrogen management strategy on N uptake and soil properties in direct seeded rice

The present investigation was emphasized to evaluate the precision nitrogen management using SPAD meter in improving N uptake as well as soil fertility status in rice crop under direct seeded condition.The experiment was conducted at Agriculture Research Farm, Bihar Agricultural University, Sabour, Bhagalpur, Bihar, India during the monsoon season, 2018 including twelve treatment combinations of three rice cultivars (Sabour Ardhjal, Shushk Samrat, Shabhagi Dhan) and four N management levels (Control, Fixed time nitrogen management (FTNM), Real time nitrogen management (RTNM), Adjustable dose of nitrogen management (ADNM)). Results revealed that Shushk Samrat among the cultivars and FTNM among N management practices have recorded highest leaf N content as well as N uptake. There is no major difference observed in soil properties and it might take few years to observe the impact of nitrogen management strategies on soil properties.

Nitrogen-management strategy through leaf-colour chart and SPAD meter for optimizing the productivity in irrigated wheat (Triticum aestivum)

A field experiment was conducted during the winter (rabi) season of 2020–21 at Bihar Agricultural University, Sabour, Bhagalpur, to study the effect leaf-colour chart (LCC) and SPAD meter on productivity of irrigated wheat (Triticum aestivum L.). The experiment, having 8 treatments, was laid out in a randomized block design. The first 4 treatments (T1 to T4 ) were LCC-based, T5 and T6 were the SPAD meter-based management practices and T7 was considered as fixed-time N management (FTNM) and T8 was kept as control where no N was applied. The SPADbased treatments T5 and T6 received 140 kg N/ha which was higher than all the other N management treatments resulted 13% higher ears/m2 and 18% higher grains/ear over the LCC-based N-management treatments. Among the LCC-based practice, treatment T4 recorded significantly highest grain yield (4.01 t/ha) but was lower (10.4%) than that of grain yield achieved in T5 treatment. The LCC-based treatments T1 to T3 though received a lower dose of N fertilizer (19%; average of T1 to T3 ) compared to the FTNM (T7 ), returns maintained the similar yield components with the FTNM. Therefore, use of farmers’ friendly and cost-effective tool LCC is very useful which saved the N fertilizer (19%) without hampering the yield components. Thus, LCC and SPAD may be effective tool for efficient need-based fertilizer N management using LCC and SPAD meter in improving crop growth for higher productivity in rational manner.

Floral hemp (Cannabis sativa L.) responses to nitrogen fertilization under field conditions in the high desert.

While most studies on floral hemp (Cannabis sativa L.) concur that additions of nitrogen (N) increase plant growth, the performance of floral hemp is heavily influenced by environmental conditions, management and cultivar selection. In regions with a short growing season, the availability of soil N may determine plant developmental rates, final inflorescence biomass and cannabinoid concentrations, but no studies have addressed this for field-grown hemp under high-desert conditions. This field study evaluated the effect of no supplemental N and N fertilization at 90 kg ha-1 on three hemp cultivars (Berry Blossom, Red Bordeaux, and Tahoe Cinco) in Northern Nevada. N increased plant height, canopy cover, stem diameter and shoot biomass, but other physiological parameters were dependent on cultivar. For instance, inflorescence biomass and inflorescence-to-shoot ratio in Red Bordeaux was not affected by N fertilization. Similarly, cannabinoid concentrations were affected by timing of harvest and cultivar but not by N treatment. We evaluated the use of a SPAD meter for ease of determining leaf N deficiency, and correlations with leaf chlorophyll content showed that the SPAD meter was a reliable tool in two cultivars but not in Tahoe Cinco. N treatment increased overall CBD yield, which was driven by increases in inflorescence biomass. Tahoe Cinco was the best CBD yielding cultivar, as it maintained a high inflorescence-to-shoot ratio regardless of N treatment. Our study suggests that even though hemp may have a positive response to soil N management, adjustments based on genotype by environment interaction should be aimed at maximizing cannabinoid yield either by increasing biomass and/or CBD concentrations as long as THC levels are within the permissible <0.3% for U.S. industrial hemp cultivation.

Evaluation of integrated crop management, organic management and natural farming in basmati rice-wheat system under Upper Indo-Gangetic Plains

Field experimentation was conducted to evaluate the comparative performance of integrated crop management, organic management and natural farming on crop growth, productivity, profitability and soil health under basmati rice-wheat system in Upper Indo-Gangetic Plains. Treatments comprised of different management practices viz. integrated crop management (ICM), organic management, natural farming (NF) and control (no nutrient) were used in experimentation. Plant height, number of effective tillers, SPAD meter reading, panicle weight, filled grains/panicle, fertility percentage and 1000-grains weight of basmati rice and wheat were observed highest under ICM followed by organic management. A significant reduction in growth and yield attributes was recorded under NF as compared to ICM and organic management. Grain yield of basmati rice was reduced by 15.2%, 51.2% and 53.9% under organic management, NF and control as compared to ICM, respectively. Similarly, 49.5%, 58.6%, and 63.8% reduction in grain yield of wheat was recorded under organic management, NF and control as compared to ICM, respectively. In comparison to ICM, system rice equivalent yield (REY) was reduced by 32.6%, 55.0%, and 59.0% under organic management, NF and control, respectively. Further, net return was 44.1% and 67.2% lower under organic management and NF as compared to ICM, respectively. Highest soil organic carbon (0.60%), available N, P, and K were found in organic management. Significantly highest soil microbial population, glomalin content and different soil enzyme activities were recorded under organic management. Overall, the integrated crop management provided balanced and continuous supply of the nutrient that resulted in higher productivity and profitability of basmati rice-wheat system.

Analysing the SPAD dynamics of water-stressed vs. well-watered sesame (Sesamum indicum L.) accessions and establishing their relationship with seed yield.

The chlorophyll content is susceptible to deficit moisture stress and may affect the plant yield. Leaf chlorophyll content is directly related to tolerance and higher productivity under deficit moisture stress (WS). The SPAD meter is an excellent tool for rapid analysis of crop chlorophyll content. Therefore, establishing a relationship between leaf chlorophyll content and seed yield is crucial in sesame, particularly under deficit moisture stress. Seeds of 37 sesame genotypes with checks were used in this study. These genotypes were mostly landraces, adapted to different agro-ecological zones in India. The selected genotypes were evaluated under well water (WW) and deficit moisture stress (WS) conditions. The SPAD readings were recorded ten (10) times each at every seven days intervals from the juvenile/first bud (30-35 days after sowing) to ripening/ physiological maturity (95-100 days after sowing) stage. This study aimed to identify the association between leaf SPAD readings (recorded at 7-days interval) and seed yield of sesame genotypes. The analysis of variance revealed the presence of significant variation in SPAD readings due to treatment (WW and WS), genotypes, and their interaction effects. The SPAD readings at all stages were positively correlated with seed yield in both WW and WS. High values of correlation coefficients were observed at 52 (r: 0.672) and 59 (r: 0.655) DAS under WS; whereas at 59 (r: 0.960), 66 (r: 0.972) and 73 (r: 0.974) DAS under WW at one percent significance level (p<0.01), which coincided with the mid-bloom stage of the sesame crop. The best-fit multiple regression model revealed that the dependence of sesame seed yield is significantly influenced by SPAD reading at 52 DAS under WS and 59 to 73 DAS under WW. Both these models provide a good fit with the chi-squared test, which compares the predicted and observed yield.