Soil Plant Analysis Development Chlorophyll Research Articles

Smartphone Contact Imaging and 1-D CNN for Leaf Chlorophyll Estimation in Agriculture

Traditional leaf chlorophyll estimation using Soil Plant Analysis Development (SPAD) devices and spectrophotometers is a high-cost mechanism in agriculture. Recently, research on chlorophyll estimation using leaf camera images and machine learning has been seen. However, these techniques use self-defined image color combinations where the system performance varies, and the potential utility has not been well explored. This paper proposes a new method that combines an improved contact imaging technique, the images’ original color parameters, and a 1-D Convolutional Neural Network (CNN) specifically for tea leaves’ chlorophyll estimation. This method utilizes a smartphone and flashlight to capture tea leaf contact images at multiple locations on the front and backside of the leaves. It extracts 12 different original color features, such as the mean of RGB, the standard deviation of RGB and HSV, kurtosis, skewness, and variance from images for 1-D CNN input. We captured 15,000 contact images of tea leaves, collected from different tea gardens across Assam, India to create a dataset. SPAD chlorophyll measurements of the leaves are included as true values. Other models based on Linear Regression (LR), Artificial Neural Networks (ANN), Support Vector Regression (SVR), and K-Nearest Neighbor (KNN) were also trained, evaluated, and tested. The 1-D CNN outperformed them with a Mean Absolute Error (MAE) of 2.96, Mean Square Error (MSE) of 15.4, Root Mean Square Error (RMSE) of 3.92, and Coefficient of Regression (R2) of 0.82. These results show that the method is a digital replication of the traditional method, while also being non-destructive, affordable, less prone to performance variations, and simple to utilize for sustainable agriculture.

Predicting chlorophyll and nitrogen content in rice using multiple regression models

Chlorophyll and nitrogen (N) content in rice at critical crop growth stages are important input parameters for crop growth and nutrient uptake models used to optimize N application. Hence, the study was conducted to predict chlorophyll and N content in rice using multiple regression-based models involving normalized difference vegetation index (NDVI), Soil Plant Analysis Development (SPAD), Customized leaf color chart (CLCC), chlorophyll and N content. An experiment was conducted with six varieties i.e. CR Dhan 312, CR Dhan 310, Lalat, Shatabdi, Swarna Shreya, CR Dhan 206 with four N levels (i.e. 0, 80, 100 and 120 kg N ha−1) in split plot design and replicated thrice. The NDVI, SPAD and CLCC readings were taken at 45, 49 and 54 days after transplanting (DAT). Plant sampling was done for estimating the chlorophyll and nitrogen content in laboratory following standard methodology. Multiple linear regressions were performed between NDVI, SPAD and CLCC readings and chlorophyll & N content in rice in different variables combinations. Multiple linear regression (MLR) models with two variables i.e. NDVI and SPAD predicted the chlorophyll and N content of rice varieties. The predicted values for nitrogen and chlorophyll were comparable to those obtained using models from individual varieties when combined data from six different varieties were used to create MLR models. The study concludes that variations in chlorophyll and N concentrations in rice can be estimated using data from optical sensors with notable accuracies.

Impact of conservation tillage practices on the growth and yield of blackgram (Vigna mungo) in rice (Oryza sativa)-blackgram cropping system

A field experiment was conducted during post rainy seasons of 2015–16, 2016–17 and 2017–18 (December-March) at research farm of Tamil Nadu Rice Research Institute, Aduthurai, Tamil Nadu to study the impact of tillage practices adopted in the rice (Oryza sativa L.) crop on the succeeding blackgram (Vigna mungo L.) grown as relay cropping. The treatment comprised of 2 tillage practices (puddled and non-puddled), 3 seed priming methods (Bio-seed priming with Rhizobium, hydropriming and no seed priming) and 2 foliar spray (2% DAP and 2% urea). The results indicated though blackgram grown as succeeding crop in the puddled tillage registered higher values of Relative water content (RWC) (83.06 and 83.72%), Specific leaf weight content (SLW) (6.83 and 6.28 g/cm2), Soil Plant AnalysisDevelopment chlorophyll meter values (40.88 and 39.75) at 30 and 45 DAS respectively, it was comparable with non-puddled tillage method. However, the blackgram sown as succeeding crop in non-puddled transplanted rice registered a greater number of nodules (23.67 and 17.44) and nodules dry weight (0.17 and 0.11 g) at 30 and 45 DAS respectively as compared to puddled transplanting. Similarly, the root length (6.93 and 8.62 cm) and root dry weight (0.151 and 0.174 g at 30 and 45 DAS respectively) were also higher with non-puddled tillage. The yield obtained under non-puddled tillage system was 11.8% higher than puddled method of tillage system. Bio-seed priming with rhizobium had higher values of growth and yield parameters, which eventually resulted in 25.0% yield increase over no seed priming. As far as foliar spray concerned, DAP 2% spray and Urea 2% spray did not differ significantly for none of the parameters except for yield.

Height Control of Greenhouse-grown Pansy Using Colored Shade Nets

Pansy (Viola ×wittrockiana) is a greenhouse crop commonly grown under black shade net; it often requires the use of chemical plant growth regulators to maintain a compact growth habit. Nonchemical efforts to alter plant morphology, such as height, would provide a more sustainable solution than chemical application. The objective of these studies was to evaluate the effects of different colors of shade nets on controlling growth and flowering of pansy. In Expt. 1, ‘Clear Yellow’, ‘Buttered Popcorn’, and ‘Deep Orange’ pansy plugs were placed under 30% blue or black shade net or, as a control group, where grown with no shade net. In Expt. 2, the same three cultivars of pansy were grown under 50% black, red, pearl, or aluminized shade net. Data were collected on plant height, plant width, flower number, plant survival, soil plant analysis development chlorophyll meter (SPAD) readings, and light quality. In Expt. 1, the blue shade net reduced height to flower and height to leaves, but also decreased flower number and plant survival as compared with black shade net. All plants under no shade died. In Expt. 2, SPAD, an indicator of plant quality by estimating leaf greenness, was found to be lower under black shade net, whereas pearl shade net led to a decrease in plant height and no effect on the number of flowers. Light quality, including red-to-far-red ratio, varied among shade treatments, whereas light intensity was reduced under aluminized, black (50%), and red shade nets compared with other shade treatments. Blue and pearl shade nets both reduced plant height, but blue shade net also reduced plant survival and flowering.

Characterisation and evaluation of wheat genetic resources for heat stress tolerance using stay-green traits

Context Post-anthesis heat stress is a major concern for wheat. Stay-green (SG) can serve as a crucial marker for plant adaptation to it. Though genetic resources provide an invaluable gene pool for crop breeding, collections are still uncharacterised and their potential is yet to be explored. Aims This study was planned to characterise and evaluate wheat genetic resources, including wild germplasm, for heat stress tolerance using SG traits as selection criteria. Methods Experiment was conducted with thirty wheat genotypes under late and very late sown environments for 2 years. Genotypes were assessed for SG traits like Normalised Difference Vegetation Index (NDVI), Soil Plant Analysis Development Chlorophyll Meter Reading (SCMR), Leaf Senescence Rate (LSR), chlorophyll fluorescence (Fv/Fm), canopy temperature (CT), phenological traits, morphological traits, yield and its attributes; and characterised into three categories viz., slow senescing, intermediate senescing and fast senescing, based on their rate of senescence. Key results Results indicate that slow-senescing genotypes had a significantly higher NDVI, SCMR and yield as compared to fast-senescing genotypes. NDVI, SCMR, Fv/Fm, days to heading, days to anthesis, days to maturity, grain weight per spike, 100-grain weight and biomass were significantly positively correlated whereas LSR and CT were significantly negatively correlated with grain yield. From the principal component analysis studies, it was revealed that genotypes with a high SCMR, a low LSR, and a high grain yield were placed together as SG genotypes. Conclusions This study confirms that genotypes with SG traits performed better under heat stress. Implications From the wild, genotypes HTW 11 (W), HTW 67 (W) and HTW 6 (W) can be utilised for heat tolerance breedings.

Nitrogen efficiency indices of potato in response to nitrogen doses estimated by algorithms and applied as top-dressing

The objective of this study was to evaluate the effect of N doses estimated by algorithms and applied as top-dressing on different nitrogen (N) efficiency indices in Asterix potatoes. Two experiments were installed in the field. The experiments were conducted in the randomized block design, in split-plot scheme, with four replicates, whose treatments, in the plots, were determined by five N doses in pre-planting and, in the subplots, by three criteria (algorithms evaluated) of top-dressing N. At 21 DAE (days after an emergency), the fourth fully developed potato leaf was evaluated with the SPAD (Soil Plant Analysis Development) chlorophyll meter. This reading was used as an indicator of the need for top dressing. In harvesting the tubers, the following variables were determined: N content in shoots and tubers, amounts of N absorbed by shoots, tubers and total N, harvest index, N use efficiency, N agronomic efficiency and physiological efficiency of N. The application criteria did not significantly influence the variables related to the content and amount of absorbed N, except for the N content of the tubers in the 2018 experiment. Of N absorbed by shoots, tubers and plants and the agronomic efficiency of N were significantly influenced by the N dose applied pre-planting. The agronomic efficiency was significantly influenced by the N dose estimated by the N cover recommendation criteria. The highest values obtained for the variables related to the content and amount of N absorbed were those under application of 200 to 300 kg ha−1 of N.

Application of multispectral UAV for paddy growth monitoring in Jitra, Kedah, Malaysia

Rice is the staple food for most people in Southeast Asia, mainly Malaysia. Unfortunately, Malaysia does not reach a 100% self-sufficiency level on rice production due to inefficiency of rice farm management, pest and disease outbreak, poorly irrigation system, and climate change. Each spectral band of electromagnetic signature in the rice crops can be identified to analyse the crop condition based on the reflectance value. Therefore, unmanned aerial vehicle (UAV) can capture different spectral band images of the rice field depending on the sensors used. This study aims to produce a paddy growth map based on the normalized difference vegetative index (NDVI) value and validate the paddy growth map using the soil plant analysis development (SPAD) data. This study was carried out at the paddy field planted with PadiU Putra rice variety in Muda Agricultural Development Authority (MADA), Jitra in Kedah. Three reading samples for each point at the paddy field within 1 m radius were recorded. Then, the samples from each point were scanned using SPAD chlorophyll meter. The image data were collected using multispectral and RGB cameras at the altitude of 60 m, and a calibrated reflectance panel was used to calibrate the image. Ground control point (GCP) was placed at the four corners of the study plot, and it was being used as a georeferencing point for aerial imagery mapping. Those images were undergone orthomosaic process to produce a single overlapped image. NDVI was used to measure the healthy level of rice crops. NDVI map had shown the distribution of NDVI value across the study plot, which includes the healthy and less healthy vegetative area. SPAD value has no significant relationship with the aerial imagery of NDVI value. The NDVI map allows the farmers to monitor the paddy growth status and effectively improve their rice farm management. In the future, advanced classification methods based on the reflectance of weed, water, and soil can be prioritized and separated into different classes, whereby the NDVI map can be plotted on the paddy crops.

Influence of plant growth-promoting endophytes Colletotrichum siamense and Diaporthe masirevici on tomato plants (Lycopersicon esculentum Mill.)

ABSTRACT The protective and growth-promoting activities of Colletrotrichum and Diaporthe endophytes on tomato plants (Lycopersicon esculentum Mill.) are underexplored. We screened 40 endophytic fungi associated with Mexican shrimp plant (Justicia brandegeana) using an in vitro dual culture assay for Fusarium oxysporum, one of the most important phytopathogens of tomato plants. The three best antagonists, Colletotrichum siamense (JB224.g1), C. siamense (JB252.g1), and Diaporthe masirevicii (JB270), were identified based on multilocus sequence analysis. They were assessed in vitro for their inhibition of F. oxysporum and phosphate solubilisation capacity, and for the production of indole acetic acid. Greenhouse experiments verified the growth-promoting effects of these endophytes and the suppression of F. oxysporum symptoms in tomato plants. Under greenhouse conditions, the JB252.g1 and JB270 isolates showed positive results for seedling emergence speed. The radicular system depth of plants inoculated with JB270 was greater than that in uninoculated plants (27.21 vs 21.95 cm). The soil plant analysis development chlorophyll metre (SPAD) index showed statistically significant results, especially for the endophyte JB224.g1 (36.99) compared to the control plants (30.90) and plants infected solely with F. oxysporum (33.64).

Complementary Nutrients in Decoupled Aquaponics Enhance Basil Performance

Aquaponics combines raising fish and growing plants by recycling water and nutrients to reduce water consumption and reliance on chemical fertilizers. Coupled aquaponics systems recirculate water between fish and plant crops, whereas decoupled systems send mineralized fish effluent and wastewater unidirectionally to an independent hydroponic loop. Decoupling enables changes to the water, such as pH adjustments and complementary nutrient additions, to promote plant performance. In this study, basil, Ocimum basilicum (L.), was transplanted into 4 L containers filled with decoupled aquaponic (DAP), nutrient-complemented decoupled aquaponic (DAP+), or chemical-based conventional hydroponic (CON) nutrient solutions and grown for 21 days at pH 5.8. Plants grown in DAP+ and CON had greater biomass, height, and Soil Plant Analysis Development (SPAD) chlorophyll index and lower root:shoot biomass ratios than those in DAP. Shoot fresh and dry biomass was 11% greater for CON than DAP+, while height, SPAD chlorophyll index, and root:shoot ratio did not differ. We concluded that added nutrients in DAP+ enhanced performance compared to DAP, and the biologically derived nutrition in DAP+ enhanced performance to be similar, but not equal, to CON. We cannot recommend specific adjustments to the targeted blend of complementary nutrients tested, but findings suggest that complementary nutrients are effective in decoupled aquaponics.

Nitrogen uptake of cocoa seedlings as a response of cocoa pod husk derived liquid organic fertilizer application in combination with urea

As nitrogen (N) has played an important role in cocoa production, both providing the N-sources alternative materials, and increasing the efficiency of fertilization are urgently required to support both crop and land productivity. Research aims to investigate the N uptake of cocoa seedlings as results of combination of liquid organic fertilizer (LOF) and urea application. To support the understanding in terms of N dynamics, SPAD (Soil Plant Analysis Development) chlorophyll content, N use efficiency (NUE) and recovery of applied nitrogen (REN) were determined with additional information related to the optimal dosage of urea to be applied to cocoa seedlings. Greenhouse experiment, using ICCRI 08 cocoa seedlings, was carried out in Kaliwining Experimental Station, Indonesian Coffee and Cocoa Research Institute, Jember, East Java. The LOF used for this experiment was made from about 1-month fermentation of cocoa pod waste in a 200 L plastic tank with additional biodecomposer to improve the biodegradation of organic materials. The experiment was designed by a completely randomized design (CRD), and taking into account two factors, i.e. the level of LOF concentration and urea application, as treatments of which their effect was determined through regular growth observations and laboratory determination. The variation of LOF concentration levels are (i) control (B0), (ii) LOF 0.25% (B1), (iii) LOF 0.50% (B2), and (iv) LOF 1% (B3). Additionally, the rates of urea applications include control (P0), 10% of fertilizer recommendation dosage (P1), 25% of fertilizer recommendation dosage (P2), and 50% of fertilizer recommendation dosage (P3). SPAD readings indicate the significant effect of urea and its combination with LOF to the increase in the chlorophyll content by 10 – 20% in compare to control. The total N uptake by cocoa tends to decrease with the increase in the concentration of LOF. With average increase of about 28% compared to control, statistical analysis suggest the insignificant different effect of treatments. The effect of LOF to the increase in the NUE, ranging from 0.50 to 0.80, in combination with specific level of urea. With 50% of urea recommendation dosage, the increase in NUE is above 40% up to 55% compared to non-LOF applied treatments. REN data interpretation indicates the higher of its values for treatments with lower level of urea applications. With the increase in the urea rate, the REN value is decreasing implying the contribution from the input of N. In this level, the REN is down to below 50% showing the lower amount of N required in compare to the N inputs. Relating the dosage of urea with N uptake shows an asymptotic type of curves. It indicates the optimal rate of urea ranging from 0.5 to 1 g urea per pot. The higher amount of LOF applied shows to decrease the optimal dosage of urea required in compare to no LOF application (B0). Though its use as source of nutrients is limited, current research may indicate the potential utilization of LOF through foliar spray to increase the efficiency of urea application.

24-epibrassinolide in association with iron enhances the photosynthetic efficiency and upregulates the antioxidant system of the Brassica juncea

24-epibrassinolide (EBL) and iron (Fe) individually are well recognized for their significant role in various biological functions of plants but their interactive effect on iron transport, stress biomarkers, photosynthetic and biochemical parameters in Brassica juncea is poorly investigated. Therefore, this study was conducted to reveal the effect of Fe in the presence of 24-epibrassinolide (EBL), an analogue of brassinosteroids (BRs) on Brassica juncea plants. Fe in the form Fe-EDTA (1, 5 or 50 µM) was supplied with nutrient solution for 5 days followed by the foliar spray with deionised water (control) or EBL (0.01 µM) on 16-day-old plants for 5 days. Plant samples of 30-day-old plants were collected for the assessment of growth and photosynthetic performance and antioxidant parameters. Results clearly indicated that Fe altered plant metabolism. Lower concentration of Fe (5 µM) increased the growth biomarkers, SPAD (soil plant analysis development) chlorophyll level and photosynthetic rate, whereas higher concentration of Fe (50 µM) proved toxic to Brassica juncea and showed reduced growth, biomass of plant, SPAD chlorophyll level, and photosynthetic traits. However, the application of EBL to Fe-stressed plants reversed the deleterious effects caused by the Fe (50 µM) by improving the activities of antioxidant enzymes and increasing the proline accumulation in plant cells that are reflected in increased plant growth and other physiological parameters. It is concluded that lower concentration of Fe could be exploited as micronutrients whereas combined application of Fe with EBL acts as a stress alleviator for the toxic effects caused by Fe alone.

Diagnosis of Nitrogen Nutrition in Rice Leaves Influenced by Potassium Levels.

Evaluation of nitrogen (N) status by leaf color is a kind of classic nutritional diagnostic method. However, the color of leaves is influenced not only by N, but also by other nutrients such as potassium (K). Two-year field trials with a factorial combination of N and K were conducted to investigate the effects of different N and K rates on soil plant analysis development (SPAD) readings and leaf N, K, magnesium (Mg), and chlorophyll concentrations. Visual inspections in leaf greenness revealed darker green leaves with increasing N rates, while paler green leaves with increasing K rates. Data showed that SPAD readings, chlorophyll, N and Mg concentrations, and the chloroplast area increased significantly with raising N rates, while declined sharply with the increase in K rates due to the antagonistic relationships between K+ and NH4 + as well as Mg2+. It was also probable that the increase in K promoted the growth of leaves and diluted their N and Mg concentrations. The paler leaf appearance resulting from the application of K may overestimate the actual demand for N in the diagnosis of rice N status. The strong antagonistic relationships between K+, NH4 +, and Mg2+ should be considered in rice production and fertilization.

A physiological Explanation of Drought Effect on Flag-Leaf Specific Weight and Chlorophyll Content of Barley

This study was carried out in Kalar technical institute, Sulaimani Polytechnic University in Garmian region, Iraq during 2016-17 and 2017-18 seasons. Five hybrid genotypes of barley were tested under drought and irrigated conditions to detect the flag-leaf specific weight, chlorophyll content index (SPAD; The Soil Plant Analysis Development chlorophyll meter) and the period from anthesis to physiological maturity. Across both years 2016-17 and 2017-18, there was no effect of drought on flag-leaf specific weight, however, SPAD was reduced by 4.77 and the period between anthesis and maturity was shortened by almost two days. Genotype 3//14 scored the highest values of flag-leaf specific weight (7.765 mg cm-2)and SPAD (25.56), and stayed green for the longest period (28.69 days) (P=0.05), showing its ability to be more tolerant to moisture reductionas compared to the other tested genotypes. In order to explain the physiological mechanisms among the assessed traits under both irrigated and drought conditions, linear regression analysis was applied for both seasons and averaged over seasons. A positive linear relationship was shownbetween flag-leaf specific weight and SPAD under both irrigated (R2=0.83; P=0.03) and drought (R2=0.76; P=0.05) conditions, explaining the high flag-leaf chlorophyll content resulting from high specific weight of leaves. The high flag-leaf specific weight was also associated with longer periods for leaves to stay-green after anthesis, under both irrigated (R2=0.91; P=0.01) and drought (R2=0.79; P=0.04) conditions, which provides a great chance to accumulate more resources of carbohydrates and protein in the grain and, consequently,a higher throughput of yield.

Assessing the most sensitive and reliable endpoints in plant growth tests to improve arsenic risk assessment

Arsenic (As) is toxic to humans and the environment. Its toxicity has been assessed in many ways, including plant growth tests integrated in As risk assessments (RA). The tiered approach used in RA schemes assumes that lower tiers are more conservative than higher tiers. Plant growth tests may comprise lower tier of a RA and include the measurement of several endpoints. However, only few of these endpoints are highly sensitive and reliable, which makes them more appropriate to comprise lower tiers. Therefore, the selection of those endpoints is needed. The present study aimed to evaluate the most appropriate endpoints of plant growth tests to use in lower tier As RA schemes. This selection of endpoints was based on their sensitivity and reliability, using different tropical soils and plant species. In order to achieve this objective, six plant species were exposed to eight levels of As contamination (0; 8; 14.5; 26; 46.5; 84; 150; 270 mg kg−1), in three different tropical soils (Oxisol, Inceptisol, and tropical artificial soil). The endpoints measured were: first germination count (FrC), plant height (PH), relative leaf area (RLA), stem diameter (SD), total germination (TG), germination speed index (GSI), dry mass (DM), number of completely expanded leaves (CEL), plant survival (PS), soil plant analysis development chlorophyll level (SPAD), and the final germination count (FnC). Toxic values for 50% of effect were estimated for each endpoint within each species and test soil, to rank them according to their sensitivity and reliability. The most sensitive endpoints were: FrC, RLA, DM, GSI, PH, and FnC, while the most reliable endpoints were: FrC, DM, GSI, DM, PH, FnC, and TG. Our findings suggest that FrC, DM, GSI, PH, and FnC are the most adequate endpoints to be used in plant growth tests as lower tiers of As RA in tropical regions.

Preliminary Study of Variable Rate Application – Organic Liquid Fertilizer by Using SPAD Chlorophyll Meter on System of Rice Intensification (SRI) Cultivation

ABSTRACTKnowing actual nutrient requirements for rice plants is crucial in supplying the correct amount of fertilizer, especially nitrogen since nitrogen is one of the most key limiting nutrients in rice cultivation. A preliminary study of variable rate application (VRA) on System of Rice Intensification (SRI) planting by using organic foliar fertilizer was carried out to determine the effectiveness of precision fertilization. Foliar fertilizer was formulated based on actual nitrogen needed by rice plants using Soil-Plant Analyses Development (SPAD) chlorophyll meter measurements. The experiment was laid out in a randomized complete block design (RCBD) with four treatments (50% fixed rate, 100% fixed rate, 150% fixed rate and VRA) and four replications for each treatment. Plant growth performances (plant heights, number of tillers, number of panicle and flower) and yield performances (grain yield, number of grain, 1000-grain weight and number of spikelets) were recorded during the study. The results showed that foliar application of VRA resulted in significantly higher yield performances; grain yield (13.65 g), number of grain (807.50), 1000-grain weight (16.79 g), and number of spikelets (7.50) compared to uniform fertilizer applications. VRA treatments had the highest SPAD readings at every planting stage during the experiment; however, a high nitrogen supply was needed during the mid-tillering stages (35 DAT) compared to other fertilizer rates. Besides, VRA application shows the most savings in term of total nitrogen supply (415 µg) compared to uniform rates application; 50% fixed rate (400 µg), 100% fixed rate (810 µg), and 150% fixed rate (1210 µg).

English

The correct management of organic fertilization has been shown as an extremely viable alternative in the production of vegetables, providing high yields concomitant to the reduction of synthetic fertilizers. The improvement of the production can be interpreted by the physiological behavior, favored by the organic fertilization with the supply of nutrients. Thus, an experiment was carried out to evaluate the gas exchange and Soil-Plant Analyses Development (SPAD) chlorophyll content in tomato plants according to types of organic fertilizers and biofertilizer doses. The experimental design was completely randomized with treatments distributed in factorial arrangement (3 x 5), referring to organic fertilizer types (T1: earthworm humus; T2: goat manure and T3: cattle manure) and biofertilizer concentrations (600, 800, 1000, 1200 and 1400 ml), with four replications. The gas exchange and the SPAD chlorophyll content in tomato plants depend on the type of organic fertilizer and the concentration of biofertilizer. It was possible to observe that increasing doses of biofertilizer in the substrate with low organic concentration increase the gas exchange in tomato plants, while high doses together with more concentrated organic fertilizers reduce these characteristics. Key words: Alternative fertilizer, Lycopersicon esculentum, photosynthesis, organic fertilizer. &nbsp

Identification and screening of nitrogen-efficient cotton genotypes under low and normal nitrogen environments at the seedling stage

BackgroundLarge quantities of nitrogen (N) fertilizer applied to cotton cropping systems support high yields but cause adverse environmental impacts such as N2O emission and water eutrophication. The development of cotton cultivars with higher N use efficiencies suitable for low-N conditions is therefore important for sustainable production. In this study, we evaluated 100 cotton genotypes in 2016 for N use efficiency and related traits at the seedling stage.MethodsSand culture experiment was conducted with low N levels (0.01 g·kg− 1) or normal N levels (0.1 g·kg− 1). We investigated plant height, SPAD value (soil plant analysis development chlorophyll meter), dry weight, N accumulation, N utilization efficiency, and N uptake efficiency. Through descriptive statistics, principal component analysis and heatmap clustering analysis, we confirmed the evaluation index system of N-efficient genotypes and the classification of N-efficient genotypes.ResultsSignificant differences were observed among N levels and genotypes for all agronomic traits and N levels. Coefficients of variation varied greatly and ranged from 6.7~28.8 and 7.4~20.8 under low-N and normal-N treatment, respectively. All traits showed highly significant positive correlations with each other, except SPAD value. The principal components under both N levels were similar, showing that total dry weight, aboveground dry weight, total N accumulation, and N uptake efficiency were important components. We confirmed these four traits as suitable screening indexes for low N tolerance. Based on the results of heatmap clustering and scatter diagram analysis of N efficiency value, 10 genotypes were found low-N tolerant, in which five varieties were inefficient under both low and normal N conditions, while four varieties were found efficient under low-N conditions but inefficient under normal-N conditions. Only one variety was efficient under both low and normal-N conditions. Meanwhile, 20 genotypes were identified as low-N sensitive ones, in which 19 genotypes were inefficient under low-N conditions but efficient under normal-N conditions, one variety was inefficient under both low and normal-N conditions.ConclusionWe preliminarily identified Kashi as a low-N tolerant and N-efficient cotton genotype, and CCRI 64 as a low-N sensitive and N-inefficient cotton genotype. Further studies should be carried out to verify the yield and heritability effect of specific genotypes in the field.

Assessment of spinach seedling health status and chlorophyll content by multivariate data analysis and multiple linear regression of leaf image features

Plant health and physiological status significantly influence chlorophyll content and photosynthetic capacity. Analysis of leaf reflectance information from digitized leaf images allows high-throughput, non-invasive and real-time estimation of chlorophyll content in a cost-effective manner. In the present study the application of multivariate data analysis tools, viz. principal component analysis (PCA) and agglomerative hierarchical clustering analysis (AHCA), has been discussed for distinguishing between spinach seedlings having high and low chlorophyll contents by simultaneously using the information provided by various image features. Further, leaf color information contained within different color spaces, viz. RGB (red, green and blue), rgb (normalized red, green and blue), HSI (hue, saturation and intensity), CIE (Commission Internationale de l’Eclairage) L∗a∗b∗, CIE-XYZ, and CIE-xyY color spaces, has been used to predict chlorophyll content in terms of SPAD (Soil Plant Analysis Development) chlorophyll meter values by multiple linear regression. It was observed that the color indices R, G, R + G, R−B, G−B, R + G−B, Y (luminance) and DGCI (dark-green color index) exhibited high correlation (R2 > 0.8) with the SPAD values. Further, subjecting the leaf reflectance information provided by these color indices to PCA and AHCA enabled a clear segregation of seedlings with high and low chlorophyll contents. SPAD values predicted by the L∗a∗b∗ color space information yielded the lowest RMSE (root mean square error) and the highest R2 (coefficient of determination) amongst the six color space features assessed. The findings of the present study indicate that concatenation of leaf reflectance information provided by different color indices may be more useful than individual color indices for assessing plant health status and predicting chlorophyll content using machine vision.

Effects of different packaging materials and methods on the physical, biochemical and sensory qualities of lettuce.

In order to maintain the qualities at postharvest stages, Korean red leaf lettuces (Lactuca sativa L. cv. Tojong-mats) were packaged with different films or perforations such as perforated polypropylene with 1320 small-sized holes (PPP-1320-hole), perforated polypropylene with 4 large-sized holes (PPP-4-hole), non-perforated polypropylene (Non-PPP), non-perforated polypropylene with anti-fogging properties (Anti-Fog-PP) or without packaging (control) and stored at 10°C up to 16days. Minimum water loss was observed in both non-perforated films (<3%) compared to 35% in control at the end of storage. Significant increase in CO2 and simultaneous decline in O2 concentration were recorded in both non-perforated films. A gradual decline in hue angle (h°) and SPAD (Soil-Plant Analyses Development) chlorophyll meter values was found in all samples during storage while the color difference (ΔE*) values showed opposite trend. However, Anti-Fog-PP treatment exhibited the least ΔE* values throughout the storage. The contents of chlorophyll a (Chl a), chlorophyll b (Chl b) and total chlorophyll (total Chl), decreased gradually in all cases with a comparatively higher declines in Non-PPP treatment on 6days, in PPP-4-hole treatment both on 12 and 16days. Anti-Fog-PP treatment exhibited the lowest chlorophyll degradation and least changes in anthocyanin content until the end of storage. Lettuces received scores for maintaining marketable limits up to 2, 4, 6, 12 and 16days under control, PPP-1320-hole, PPP-4-hole, Non-PPP and Anti-Fog-PP packaging treatments, respectively. Results indicated that Anti-Fog-PP treatment could provide better postharvest qualities along with extended marketable life for about 2weeks during storage at market display temperature.

Leaf chlorophyll and nitrogen dynamics and their relationship to lowland rice yield for site-specific paddy management

The optimum rate and application timing of Nitrogen (N) fertilizer are crucial in achieving a high yield in rice cultivation; however, conventional laboratory testing of plant nutrients is time-consuming and expensive. To develop a site-specific spatial variable rate application method to overcome the limitations of traditional techniques, especially in fields under a double-cropping system, this study focused on the relationship between Soil Plant Analysis Development (SPAD) chlorophyll meter readings and N content in leaves during different growth stages to introduce the most suitable stage for assessment of crop N and prediction of rice yield. The SPAD readings and leaf N content were measured on the uppermost fully expanded leaf at panicle formation and booting stages. Grain yield was also measured at the end of the season. The analysis of variance, variogram, and kriging were calculated to determine the variability of attributes and their relationship, and finally, variability maps were created. Significant linear relationships were observed between attributes, with the same trends in different sampling dates; however, accuracy of semivariance estimation reduces with the growth stage. Results of the study also implied that there was a better relationship between rice leaf N content (R2=0.93), as well as yield (R2=0.81), with SPAD readings at the panicle formation stage. Therefore, the SPAD-based evaluation of N status and prediction of rice yield is more reliable on this stage rather than at the booting stage. This study proved that the application of SPAD chlorophyll meter paves the way for real-time paddy N management and grain yield estimation. It can be reliably exploited in precision agriculture of paddy fields under double-cropping cultivation to understand and control spatial variations.