Top Leaf Research Articles

Early evaluation of adjuvant effects on topramezone efficacy under different temperature conditions using chlorophyll fluorescence tests

Proper selection of adjuvant applications is an important strategy to enhance herbicide efficacy and reduce active ingredient input especially under adverse environmental conditions. In this study, a two-factor split-plot-design experiment was conducted to evaluate the effects of two adjuvants on the efficacy of topramezone on the grassy weed species giant foxtail (Setaria faberi Herrm.) and the broadleaved weed species velvetleaf (Abutilon theophrasti Medik.) under three different temperature conditions. The two tested adjuvants were methylated seed oil (MSO) and organosilicone. Three temperature levels, 35/30°C, 25/20°C, and 15/10°C (day/night), were used in the laboratory and greenhouse experiment. Plant chlorophyll fluorescence measurements shortly after herbicide application and classic whole-plant bioassay methods were used to evaluate the herbicide efficacy among the different treatments. Results indicated that the maximum quantum efficiency (Fv/Fm) of the top leaf of the weeds treated with topramezone mixed with MSO was significantly lower than that of the weeds treated with topramezone mixed with organosilicone and without an adjuvant at 2–3 days after treatment under all three temperature levels. The herbicide response of the plants treated with topramezone mixed with organosilicone and topramezone alone was not significantly different. These results corresponded well with the results of the classic whole-plant test. MSO has been shown to be good at enhancing the efficacy of topramezone on these weed species under all three temperature conditions. The measurement of chlorophyll fluorescence is a promising technique for evaluating the effects of adjuvants on the efficacy of herbicides shortly after herbicide treatment.

COMPERATIVE STUDY ON HERBAL ANTIOXIDANT PRESENT IN BRYOPHYLLUM PINNATUM PARTS (LEAVES, STEM AND ROOTS)

Herbs are plantations that lack the wood tissue of trees or shrubs. Herbs are plants grown for their medicinal, flavouring, or aromatic properties. Herbal treatments are safe and efficient for treating a wide range of ailments. Western medicine, or allopathy, is primarily reliant on medicinal plants for some of its constituents. Herbal plants are the traditional and widely used type of medication, according to research. Until the last century, most remedies were made by hand, either from plants or animals. Synthetic pharmaceuticals are becoming increasingly popular, whereas natural drugs are showing promise in treating various disorders. A perennial plant thrives in India's wet and hot regions, like Bengal. It has 25 genera and 450 species. Succulent perennials have hollow stems, four-angled leaves, and numerous branches. The leaves are 10-20 cm long and decussate. A long petiole surrounds the three- to seven-foliate top leaf. They are dark green and scalloped with red ribbons. 30- 35 cm long, 2–4 cm petioles, 6–8 X 3-5.5 cm blades, with latent buds that can develop into healthy plantlets with an acute tip8. Rooting vegetative buds are on the leaves. This herb has been used for generations to heal many ailments. These studies look at the plant's acute toxicity, antiulcer effectiveness, and pharmacognostic properties. The plant's macrostructure varied. Microscopic investigation revealed lignified walls in root and stem bark. Phytochemical analysis can identify plant metabolites. Leaves, stems, and roots had more physiologically active components than the other three plant sections. Although more research is required to identify the molecules and their potential health effects, these substances must be extracted and evaluated for future application. This study's findings support B. Pinnatum medicinal qualities. B. Pinnatum roots, stems, and leaves contain bioactive compounds worth investigating. This could help B. Pinnatum-based pharmaceuticals.

Response of Shoot Pruning on Growth, Flowering and Fruiting Characteristics of Guava under Sub-Himalayan Terai Region of West Bengal

Guava is one of the important fruit crops grown worldwide. Shoot pruning improves the emergence of new flush and its role on flowering and fruiting characteristics was evaluated on this experiment. The effect on shoot pruning height and removal of top leaf bud by pinching was assessed on growth, flowering and fruiting characteristics of guava cv. L-49. The experiment was conducted at Uttar Banga Krishi Viswavidyalaya There were two factors heading back and pinching. Heading back at the level of, Pundibari, Cooch Behar, West Bengal. 90, 120 and 150cm was done in January and pinching of one leaf pair was performed during the last week of June, 2018.The heading back at the level of 120 cm and no pinching were most effective for number of flowering bud (179.33), number of flowers (139.83), number of fruit set (95.33), total number of fruits (64.66), ascorbic acid (190.35 mg/100g), titratable acidity (0.28%) and heading back at the level of 120 cm and one pinching were effective in increasing number of primary shoots (39.50), flowering percentage (80.18%), fruit weight (172.00g).

Vertical profile of photosynthetic CO<sub>2</sub> response within rice canopy

Leaf-specific Farquhar-von Caemmerer-Berry (FvCB) model was fitted to characterize the vertical profile of photosynthetic CO2 response within rice canopy. Leaf-position-specific and canopy average FvCB models were fitted to study a suitable leaf representing photosynthetic parameters at the canopy scale. The results showed that leaf photosynthesis was limited by Rubisco activity or ribulose-1,5-bisphosphate regeneration under field conditions. The maximum rate of carboxylation, maximum rate of electron transport, rate of triose phosphates utilization, and light respiration rate in the FvCB model reached the highest values for the top second leaf and then decreased, while the mesophyll diffusion conductance kept decreased in downward leaves. The integrated photosynthetic CO2-response curves for the top fourth and fifth leaves were appropriate for estimating parameters in the FvCB model at the canopy scale.

Phytochemical and pharmacological profile review of Bryophyllum pinnatum

Herbs are plants grown for their medicinal, flavoring, or aromatic properties. Herbal treatments are safe and efficient for treating a wide range of ailments. Western medicine, or allopathy, is primarily reliant on medicinal plants for some of its constituents. Herbal plants are the traditional and widely used type of medication, according to research. Until the last century, most remedies were made by hand, either from plants or animals. Synthetic pharmaceuticals are becoming increasingly popular, whereas natural drugs are showing promise in treating various disorders. A perennial plant thrives in India's wet and hot regions, like Bengal. It has 25 genera and 450 species. Succulent perennials have hollow stems, four-angled leaves, and numerous branches. The leaves are 10–20 cm elongated and decussate. A long petiole surrounds the three- to seven-foliate top leaf. They are dark green and scalloped with red ribbons. 30-35 cm long, 2–4 cm petioles, 6–8 X 3-5.5 cm blades, with latent buds that can develop into healthy plantlets with an acute tip. Rooting vegetative buds are on the leaves. This aromatic plant has been used for groups to heal many ailments. These studies look at the plant's acute toxicity, antiulcer effectiveness, and pharmacognostic properties. The plant's macrostructure varied. Microscopic examination discovered lignified walls in the root and stem bark. Phytochemical examination can identify plant metabolites. Leaves, stems, and roots had more physiologically lively constituents than the other three plant sections. Although more research is required to identify the molecules and their potential health effects, these substances must be extracted and evaluated for future application. This study's findings support Bryophyllum pinnatum medicinal potentials. B. pinnatum roots, stems, and leaves contain bioactive compounds worth investigating. This could help B. pinnatum-based pharmaceuticals.

Genome-wide investigation of ZINC-IRON PERMEASE (ZIP) genes in Areca catechu and potential roles of ZIPs in Fe and Zn uptake and transport

ABSTRACT Iron (Fe) and Zinc (Zn) are essential nutrient elements for plant growth and development. Here, we observed the effects of Fe and Zn deficiency in seedlings of Areca catechu L. (areca palm), one of the most cultured palm trees in tropic regions. Results revealed that Fe deficiency causes strong chlorosis with the significantly decreased chlorophyll biosynthesis level and photosynthetic activities in the top third young leaf (L3) of seedlings. Zn deficiency caused light chlorosis in all three young leaves which slightly decreased chlorophyll biosynthesis and photosynthetic activities. Analysis of the Fe and Zn concentration in leaves and roots indicated that absorption and distribution of these two ions share cooperative pathways, since Zn deficiency caused Fe increasing, and vice versa. Therefore, we focused on the ZINC-IRON PERMEASE (ZIP) genes in areca trees. From the whole-genome data set we obtained, 6 ZIP genes were classified, and a phylogenetic tree was constructed with other 38 ZIP genes from model plants to find their potential functions. We also analyzed the expression pattern of AcZIP1-6 genes under Zn and Fe deficiency by transcriptomic approaches. With these results, we constructed an expression atlas of AcZIP1-6 genes in leaves and roots of areca seedlings with the dynamic expression levels under Fe and Zn deficient conditions. In conclusion, we provide evidence to understand the absorption and transport of nutrient elements, Fe and Zn, in the tropic agricultural plant A. catechu.

Development of critical nitrogen dilution curves for different leaf layers within the rice canopy

Understanding the effect of nitrogen (N) vertical distribution within the rice canopy at different growth stages and development of critical nitrogen dilution curves for upper leaf layers will not only help accurate estimations of the spatial and temporal variation in N status, but will also provide a basis for analyses of N nutrition in rice. Based on a three-year field experiment with 2 rice varieties, 3 N levels and 4 planting densities, the effect of heterogeneity in N vertical distribution on the nitrogen nutrition index (NNI) was then determined, and for the first time, critical N dilution curves of upper leaf layers were constructed based on a Bayesian statistical model. The relationship for NNI entire canopy and its relationship with the other tested leaf layers was investigated. The leaf layer suitable for analyses of N nutrition and directly inversion of NNI by remote sensing is determined. The results revealed that the main contributor to plant N concentration (PNC) of entire canopy (PNCCanopy) was found to be the lower leaf layer of the rice canopy, and may lead to misdiagnosis under the non-N-limiting condition by using the canopy level based NNI. The PNC of top half leaf layer of the canopy was more stable in terms of short-term environmental changes, and more accurately representing the overall N status. The top half leaf layer was the main contributor to canopy reflectance. Thus, compared with the NNI of other upper leaf layers, the NNI of the top half leaf layer is more suitable for direct inversion by using CI (1113, 743) with the R2 = 0.70. Overall, these findings suggest that the NNI of the top half leaf layer is the optimal remote sensing indicator of N nutrition in rice.

Evaluation of wild rice MAGIC population for biophysical parameters and yellow stem borer resistance

Field evaluation of 50 wild rice MAGIC population along with susceptible check, TN 1, stem borer resistant donor O.glaberimma (Acc.No. CG 14) and local checks TRY 2 and TRY 3 was done at Anbil Dharmalingam Agricultural College and Research Institute, Trichy. Five MAGIC genotypes, WRM-6, WRM-12, WRM-57, WRM-111 and WRM-126 showed resistance at the vegetative stage while 12 genotypes viz., WRM-3, WRM-6, WRM-30, WRM-56, WRM-57, WRM-58, WRM-72, WRM-74, WRM-111, WRM-112, WRM-115, WRM-126 along with O.glaberriema showed resistance to yellow stem borer during the reproductive stage. Correlation studies were carried out with biophysical parameters and yellow stem borer damage. Results revealed that the trichome density was significantly negatively correlated whereas, stem girth was significantly positively correlated at the vegetative stage and significantly negatively correlated at the reproductive stage. While, plant height, top internodal length and leaf length were significantly negatively correlated and leaf breadth is significantly positively correlated. Key words: Yellow stem borer, resistance, wild rice MAGIC population, biophysical characters

Evaluation of organic and inorganic fertilizers on chemical and biochemical quality constituents of burley tobacco: Influence of fertilizers on chemical and biochemical quality of burley tobacco

A field experiment was conducted during 2011-13 at Burley Tobacco Research Centre, Kalavacharla, East Godavari district, Andhra Pradesh to study the effect of organic and inorganic manures viz., four formulations of organic manures (neem cake, pongamia cake, filter press cake, poultry manure, FYM and vermicompost in different ratios) and two levels of inorganic nitrogen fertilizers (120 and 160 kg N /ha) on chemical and biochemical quality constituents of burley tobacco. Cured leaf samples from bottom, middle and top leaf positions in different treatments were analysed for chemical and biochemical quality constituents. Total chlorophylls, carotenoids and nitrate nitrogen varied from 0.116 to 0.388, 0.161 to 0.531, 3.87 to 8.06 mg/g, respectively. Chlorophylls and carotenoids were higher in manure treatments compared to inorganic treatments. Polyphenols viz., chromogenic acid and rutin ranged from 0.58 to 3.89 mg/g and 0.94 to 2.85 mg/g respectively. Polyphenols were less with organic manures compared to inorganic manures. Proline content varied from 0.506 to 3.7 mg/g. Organic manures showed higher proline compared to inorganic Nitrogen. Chemical quality parameters viz., nicotine, reducing sugars and chlorides ranged from 0.4 to 1.73%, 0.49 to 1.93% and 0.39 to 2.84% respectively. Reducing sugars content is high with organic manure application compared to inorganic nutrients. Activity of soil enzymes is high with organic compared to inorganic manures. Manure treatments not only increased the content of carotenoids, proline, reducing sugars, chlorophyll, and free fatty acids which play an important role in the quality of tobacco but also decreased the levels of polyphenols and nitrate nitrogen, which are negatively correlated with the quality of tobacco. Among the different organic manures, manure A (neem cake, pongamia cake, filter press cake, poultry manure, FYM and vermicompost in the ratio of 2:2:2:2:1:1) showed superiority followed by Manure C (neem cake, pongamia cake, filter press cake, poultry manure, FYM and vermicompost in the ratio of 1.5:1.5:5:2:1:2) in their influence on chemical quality parameters of Burley tobacco.

Predictive Modeling of Brown Rust of Sugarcane Based on Temperature and Relative Humidity in Florida.

Logistic regression models were developed from 5 years (2014 to 2018) of disease severity and weather data in an attempt to predict brown rust of sugarcane at the Everglades Research and Education Center in Belle Glade, Florida. Disease severity (percentage area of the top visible dewlap leaf covered by rust) was visually assessed in the field every 2 weeks for two varieties susceptible to brown rust. A total of 250 variables were derived from weather data for 10- to 40-day periods before each brown rust assessment day. A subset of these variables were then evaluated as potential predictors of severity of brown rust based on their individual correlation or their biological meaningfulness. Analyses of correlation and stepwise logistic regression allowed us to identify afternoon humid thermal ratio (AHTR), temperature-based duration variables, and their interaction terms as the most significant variables associated with brown rust epidemics of sugarcane in Florida. The nine best predictive models were identified based on model accuracy, sensitivity, specificity, and estimates of the prediction error. The prediction accuracy of these models ranged from 73 to 85%. Single-variable model BR2 (based on AHTR) classified 89% of the epidemic and 81% of the nonepidemic status of the disease. More than 83% of the epidemics and 81% of the nonepidemic status of sugarcane brown rust was correctly classified via multiple-variable models. These models can be used as components of a rust disease warning system to assist in the management of brown rust epidemics of sugarcane in south Florida.

Total fungi profile in dried corn using traditional drying system in Kendal, Central Java Province, Indonesia

Harvesting method is the key factor to receive agriculture product with maximum value on its categories including microbiological content. Recent study exposed the total fungi as the effect from the drying technology in the Kendal, Central Java Province as traditional drying method that has been used in the most field. Harvesting period was done at 100 day of plantation with the following step: reducing the top leaf then followed by drying in the field for 7 days. The corn was obtained from 15 plants in 3 separated areas. The fresh corn was then transferred to the laboratory and analyzed for total fungi. As result, the total of fungi was able to be detected at amount of more than 1 Log CFU/ml. This finding was very important information for the distributor to choose best handling of storage. As conclusion, the total fungi of corn using traditional drying was able to be analyzed and exposed.

Effect of leaf position and days post-infiltration on transient expression of colorectal cancer vaccine candidate proteins GA733-Fc and GA733-FcK in Nicotiana benthamiana plant.

Immunization with thetumor-associated antigen GA733 glycoprotein, which is highly expressed in colorectal cancer, is considered to be a promising strategy for cancer prevention and treatment. We cloned a fusion gene of GA733 and immunoglobulin Fc fragment (GA733-Fc), and that of GA733-Fc and an endoplasmic reticulum retention motif (GA733-FcK) into the Cowpea mosaic virus (CPMV)-based transient plant expression vector, pEAQ-HT. Agrobacterium tumefaciens (LBA4404) transformed with the vectors pEAQ-HT-GA733-Fc and pEAQ-HT-GA733-FcK was infiltrated into the leaves of Nicotiana benthamiana plants. To optimize harvesting of leaf to express therapeutic glycoproteins both spatially and temporally, protein expression levels at various leaf positions (top, middle, and base) and days post-infiltration (dpi) were investigated. The GA733-Fc and GA733-FcK genes were detected in leaves at 1–10 dpi using PCR. As assessed by western blot, GA733-Fc and GA733-FcK were expressed at the highest levels in the top leaf position at 5 dpi, and GA733-FcK was expressed more than GA733-Fc. The proteins were successfully purified from infiltrated N. benthamiana leaves using protein A affinity chromatography. ELISA verified that an anti-GA733 antibody recognized both purified proteins. Thus, a functional GA733-Fc colorectal cancer vaccine protein can be transiently expressed using a CPMV virus-based vector, with an optimized expression time and leaf position post-infiltration.

Monitoring of leaf nitrogen content of winter wheat using multi-angle hyperspectral data

ABSTRACT Hyperspectral technology, which has been used in rapid and non-destructive monitoring of crop nitrogen status, is of great significance for the nitrogen fertilization management in modern agriculture. However, most researches collect hyperspectral data from the vertical angle, always leading to the inaccurate estimation of crop nitrogen. Studies have found that using multi-angle spectral data could improve the accuracy in estimating crop leaf nitrogen content (LNC). In this study, the LNC at different leaf positions of winter wheat under five nitrogen treatments was measured and the multi-angle spectral reflectance of leaves were collected. The results showed that the top third leaf were the most sensitive to nitrogen application rate. Correlation analysis showed that the correlation between LNC and spectral reflectance obtained at 0° was the highest, followed by that between LNC and spectral reflectance obtained at 10°, 30°, 40°, and 20°. Moreover, a model based on the multi-angle composite vegetation index (MACVI) for LNC estimation was constructed through combining the difference vegetable index (DVI), the normalized difference vegetable index (NDVI), and the ratio vegetable index (RVI) and using the spectral data obtained from multiple leaf inclination angles, finding that this model could improve the estimation accuracy. The accuracy of the model based on the spectral reflectance obtained at 0°, 10°, and 20° was higher than the others, and the coefficient of determination (R 2) for the MACVID,R-based model was the highest. The MACVI-based model proposed in this study could effectively improve the estimation accuracy of winter wheat nitrogen content, and provide scientific guidance for the nitrogen fertilization management in winter wheat cultivation.

Vertical distribution of gas exchanges and their integration throughout the entire canopy in a maize field.

Fluxes of carbon and water along a vertical profile within a canopy, particularly the associations between canopy and ecosystem levels, are not well studied. In this study, gas exchange along the vertical profile in a maize canopy was examined. The relationships between leaf- and ecosystem-level carbon and water fluxes were compared. The results from research conducted over two growing seasons showed that during vegetative growth, the top and middle leaf layers in the canopy contribute most to the carbon and water fluxes of the entire canopy. During the grain-filling stage, gasexchange processes were performed mostly in the middle leaves with and near the ears. Significant relationships were observed between the net ecosystem CO2 exchange rate (NEE) plus soil respiration and the assumed canopy levels (Acanopy) and between evapotranspiration rates at the ecosystem (ET) and assumed canopy levels (Ecanopy). This highlights the close associations between these parameters by integrating the leaf gasexchange rates measured in a conventional leaf cuvette and those at the ecosystem level via the eddy covariance technique. These results improve our understanding of how carbon assimilation varies vertically within a canopy, highlighting the critical role of ear leaves.

Effect of leaf distribution pattern on the interception storage capacity of leaf litter under simulated rainfall conditions

AbstractRainwater interception by leaf litter is an important part of forest hydrological processes. The objective of this study was to investigate the interception storage capacity (ISC) of woodland leaf litter for three leaf distribution patterns, one flow path, two flow paths, and three flow paths, manually simulated via one‐by‐one leaf connection in the top leaf litter layer. A random pattern served as the control. Three different slopes (0°, 5° and 25°, representing flat, gentle and steep slopes, respectively) and two contrasting leaf litters (needle‐leaf litter, represented by P. massoniana leaves, and broad‐leaf litter, represented by C. camphora leaves) with a biomass of 0.5 kg/m2 per unit area were applied, at a rainfall intensity of 50 mm/h. Results suggested that leaf distribution pattern greatly impacts litter drainage and hence affects leaf litter ISC. The delaying capacity of litter drainage initiation and ISC of broad‐leaf litter were higher than those of needle‐leaf litter under the same slope conditions. The maximum ISC (Cmax) and minimum ISC (Cmin) of leaf litter at flat and gentle slopes were higher than those at steep slope. Cmin of the broad‐leaf litter was two times higher than that of needle‐leaf litter on average. When raindrops reached the litter layer, some were temporarily intercepted by the top litter layer while others infiltrated leaf litter sublayer along leaf edges, and in the process, some rainwater flowed through litter layer and contributed to lateral litter drainage along the potential flow path formed by leaves. The lateral litter drainage of broad‐leaf litter was higher than that of needle‐leaf litter, and the partitioning of rainwater into lateral litter drainage increased with increases in slope. The difference in leaf litter Cmax among different slopes and leaf shapes decreased with flow path increasing. Therefore, leaf distribution pattern notably impact leaf litter ISC, which is similar to leaf shape and slope impacts. On inclined slopes, avoiding leaf accumulation to form flow path is helpful for improving ISC.

Generating Better Leaf Traits in M2 Lines of Fourteen Ethiopian Sesame ( <i>Sesamum Indicum L</i>) Genotypes Through the Treatment of Their Seeds with Sodium Azide

Sesame (Sesamum indicum L.) is one of the oldest oil crops. It has been cultivated in Ethiopia since ancient times with low production and productivity. Efforts towards improving its productivity are highly needed. Mutation breeding can help in generating vital data for sesame improvement programs to develop adaptive and high performing genotypes. The present study explored into the effects of sodium azide (NaN3) on quantitative and qualitative leaf traits in M2 lines of 14 Ethiopian sesame genotypes using seeds collected from Humera Agricultural Research Center, Tigrai, Ethiopia. Qualitative data on leaf color (LC), leaf hairiness (LH), leaf arrangement (LA), leaf shape (LS), basal leaf profile (BLP), basal leaf margin (BLM), and leaf angle to main stem (LAMS) as well as quantitative data on length of basal leaf (LBL), length of top leaf (LTL), width of basal leaf (WBL), width of top leaf (WTL), length of marginal leaf (LML), and width of marginal leaf (WML) were recorded and analyzed using analysis of variance, clustering analysis, Mahalanobis distance, and principal component analysis. Generally speaking, NaN3 treatment of seeds has brought about many distinct and statistically significant phenotypic changes in quantitative and qualitative leaf traits in M2 lines of the genotypes. The changes in the NaN3 treated and locally adapted genotypes of Gumero and Zeri Tesfay are promising; producing the highest mean LBL (p ≤ 0.01). Treatment of seeds of Baha Necho, Gumero, and Hirhir developed the highest mean WBL. Locally adapted genotypes have responded to the NaN3 treatment positively by generating better leaf traits as compared to research improved ones. This study was the first of its kind in exploring into the effects of NaN3 seed treatment of sesame genotypes on leaf traits. The findings will serve as steppingstone to look into the effects of the changes in sesame yield and initiate future genetic and molecular studies on the responsive genotypes.

Leaf area index estimation using top-of-canopy airborne RGB images

Leaf Area Index (LAI) is one of the most important biophysical properties of a crop, used in detecting long-term water stress, estimating biomass, and identifying crop growth stage. Remote sensing based LAI estimation techniques perform well for early growth stages but tend to produce high error during the crop reproductive stage due to canopy closure. Moreover, estimation of the true LAI from individual leaf measurements remains a challenge. Consequently, two alternate methods have been developed and compared for estimating the LAI of a maize crop using top-of-canopy RGB images collected throughout the growing season using a hexacopter. Both methods used the RGB images to estimate the canopy height and the green-canopy cover together with a ‘vertical leaf area distribution factor’ (VLADF) from allometric relations (using crop height from RBG images and days after sowing). The first method used an empirical approach to estimate the LAI from training a linear function of the above inputs to Licor canopy analyser values of LAI. The method was trialled for a research farm located in a semi-arid area of southern peninsula India and found to have validation results with an R2 of 0.84 and RMSE of 0.36 for the unused portion of the Rabi (post-monsoon) season data of 2018–19, and R2 of 0.77 and RMSE of 0.45 for the Rabi 2019–20 season data when compared with Licor LAI values. While seemingly acceptable, the Licor canopy analyser gives a foliage area index and so the accuracy of this model was very low (R2 of 0.56 and RMSE of 1.34) when evaluated with true LAI from manual measurements of the leaf area. Consequently, a refinement was introduced using only VLADF, green-canopy cover estimates from the RBG images, and a field measured top leaf angle. The output derived from this conceptual model had an R2 of ~0.6 and RMSE of 0.73 when compared with the true LAI values. Importantly, the LAI from this conceptual model was found to be unaffected by canopy closure during the reproductive stage of the crop.

Genetic diversity studies on leaf yield and its component traits in FCV tobacco (Nicotiana tobacum L.) germplasm collection

The present study was aimed to assess the extent of genetic diversity with sixty-six genotypes of FCV tobacco (Nicotiana tobacum L.) by using Mahalanobis’ D² statistics at AINP (Tobacco), Zonal Agriculture and Horticultural Research Station, UAHS, Shivamogga, Karnataka during Kharif-2019-20 in RCBD design with two replications. The 66 genotypes were grouped into eight clusters based on D² analysis. The cluster II had maximum with 29 genotypes followed by clusters I, III, V, and IV had the minimum with 16, 16, 8 and 5 genotypes respectively and remaining clusters were solitary. The highest inter cluster distance was observed between cluster VI and VIII and the lowest between clusters II and VIII. Cluster V had exhibited highest intra cluster distance and the lowest was observed in cluster VI, VII and VII. The character days to flowering, top grade equivalent and green leaf yield showed maximum contribution towards total genetic divergence. On the basis of cluster mean, cluster VI was superior for plant height, number of leaves per plant and leaf length. The maximum leaf width was observed in cluster VIII, while cluster VII sowed superiority for days to flowering. The cluster IV showed highest green leaf yield, cured leaf yield and top grade equivalent. Thus, the genotypes involved in these clusters may be taken into consideration for better parents for generating variability for the respective characters and their rational improvement.

Genome-Wide Development and Validation of Cost-Effective KASP Marker Assays for Genetic Dissection of Heat Stress Tolerance in Maize.

Maize is the third most important cereal crop worldwide. However, its production is vulnerable to heat stress, which is expected to become more and more severe in coming years. Germplasm resilient to heat stress has been identified, but its underlying genetic basis remains poorly understood. Genomic mapping technologies can fill the void, provided robust markers are available to tease apart the genotype-phenotype relationship. In the present investigation, we used data from an RNA-seq experiment to identify single nucleotide polymorphisms (SNPs) between two contrasting lines, LM11 and CML25, sensitive and tolerant to heat stress, respectively. The libraries for RNA-seq were made following heat stress treatment from three separate tissues/organs, comprising the top leaf, ovule, and pollen, all of which are highly vulnerable to damage by heat stress. The single nucleotide variants (SNVs) calling used STAR mapper and GATK caller pipelines in a combined approach to identify highly accurate SNPs between the two lines. A total of 554,423, 410,698, and 596,868 SNVs were discovered between LM11 and CML25 after comparing the transcript sequence reads from the leaf, pollen, and ovule libraries, respectively. Hundreds of these SNPs were then selected to develop into genome-wide Kompetitive Allele-Specific PCR (KASP) markers, which were validated to be robust with a successful SNP conversion rate of 71%. Subsequently, these KASP markers were used to effectively genotype an F2 mapping population derived from a cross of LM11 and CML25. Being highly cost-effective, these KASP markers provide a reliable molecular marker toolkit to not only facilitate the genetic dissection of the trait of heat stress tolerance but also to accelerate the breeding of heat-resilient maize by marker-assisted selection (MAS).

Low nitrogen induces root elongation via auxin-induced acid growth and auxin-regulated target of rapamycin (TOR) pathway in maize

Under low nitrogen (N) supply, an important adaption of the maize root system is to promote the root elongation so as to increase N uptake from a larger soil space. The underlying physiological mechanism is largely unknown. In the present study, two maize inbred lines (Ye478 and Wu312) were used to study the possible involvement of the auxin and target of rapamycin (TOR) pathway in low-N-induced root elongation. Compared to Wu312, primary root elongation of Ye478 was more sensitive to low nitrate supply. Correspondingly, more auxin was accumulated in the root tip, and more protons were secreted, increasing the acidity of the apoplast space. On the other hand, low-N-induced root elongation was greatly reduced when shoot-to-root auxin transport was inhibited by applying N-1-naphthylphthalamic acid (NPA) at the plant base or by pruning the top leaf where auxin is mostly synthesized. Furthermore, exogenous application of TOR inhibitor also eliminated the response of root elongation under low N. The content of TOR kinase and the expression of TOR pathway-related genes were significantly changed when shoot-to-root auxin transport was reduced by NPA treatment. Taken together, it is concluded that low-N stress increases shoot-to-root auxin transport which enhances root elongation via auxin-dependent acid growth and the auxin-regulated TOR pathway in maize.