İNSANSIZ HAVA ARACI TEKNOLOJİSİ KULLANILARAK AYÇİÇEĞİ (HELİANTHUS ANNUUS) BİTKİSİNİN KLOROFİL İÇERİKLERİNİN TAHMİN EDİLEBİLİRLİĞİNİN ARAŞTIRILMASI

High-resolution images obtained with multispectral cameras mounted on unmanned aerial vehicles (UAVs) offer significant potential for agricultural monitoring activities. Chlorophyll content is one of the important parameters in monitoring the growing periods of sunflower plants. In this study, the potential of UAV technology to monitor spatial and temporal changes of sunflower (Helianthus annuus) chlorophyll content was tested. Chlorophyll and vegetation indices calculated using multispectral images taken from the UAV were compared with field chlorophyll measurements using a Spad meter. Significant (p<0.01) high correlations were obtained between the calculated indices and chlorophyll values. The results revealed that the chlorophyll content of sunflower plants can reliably be modeled at p<0.001 significance level using a multivariate linear regression model. The model obtained could successfully explain 28% 𝑅𝐴𝑑𝑗 2 = 0.28 of the variation in chlorophyll content of sunflowers. The results showed that the models developed between Spad measurement and UAVimages were successful in explaining the variation at a high level of importance. However, although statistically significant, the indices produced in the study could only explained 28% of the variation in chlorophyll content of sunflower plants. Keywords: Sunflower, UAV, Spad meter, Estimation, Vegetation indices

External green light as a new tool to change colors and nutritional components of inner leaves of head cabbages

The color and nutritional quality of vegetables directly affect the choices of consumers and thus affect the commercial value of the vegetable products. Green light can penetrate the outer leaves and reach the inner leaves to promote photochemical reaction of the overlapping leaves of head vegetables. However, whether this promotion can increase the nutritional components and change the color of the inner leaves of head cabbages, which is one of the major head vegetables largely produced worldwide, remains unclear. Therefore, we investigated the changes in the colors and the concentrations of chlorophyll (Chl) and carotenoid of the inner leaves of two types of cabbages by externally irradiating the cabbage with green light. The results showed that a short-term (48 h) irradiation with low light intensity (50 μmol m−2 s−1) of green light enhanced the Chl concentration and colors of the inner leaves of cabbages, and the positive changes of these indicators increased as the leaf layers approached the head center of the cabbage. Simultaneously, we also establish a method to effectively estimate the Chl concentration using luminosity (L*) and greenness (− a*) when the Chl concentration is so low that it is difficult or not possible to be measured by SPAD meter. Our findings demonstrated that green light, as a new tool, can be used to control the colors and nutritional components of the inner leaves of cabbages. The discoveries will help produce head vegetables with the preferred phenotype desired by consumers using a plant factory with artificial lighting.

Precision Nitrogen Management for Enhancing Yield and Quality of Fodder Maize

A field experiment was conducted during Kharif 2020 at Dry land Agriculture Research Station, Rangreth, Srinagar, Kashmir on Precision Nitrogen Management for enhancing fodder yield and nitrogen use efficiency in forage maize variety SFM-1 (KDFM-1) planted in a spacing of 30 x10 cm. The treatments consisted of T1 (No N), T2 50 kg N/ha (40% N basal) + remaining based on SPAD meter critical value of 40, T3 50 kg N/ha (40% N basal) + remaining based on SPAD meter critical value of 50, T4 50 kg N/ha (40% N basal) + remaining based on LCC 4, T5 50 kg N/ha (40% N basal) + remaining based on LCC 5, T6 100 kg N/ha (40% N basal) + remaining based on SPAD meter critical value of 40, T7 100 kg N/ha (40% N basal) + remaining based on SPAD meter critical value of 50, T8 100 kg N/ha (40% N basal) + remaining based on LCC 4, T9 100 kg N/ha (40% N basal) + remaining based on LCC 5, T10 150 kg N/ha (40% N basal) + remaining based on SPAD meter critical value of 40, T11 150 kg N/ha (40% N basal) + remaining based on SPAD meter critical value of 50, T12 150 kg N/ha (40% N basal) + remaining based on LCC 4, T13150 kg N/ha (40% N basal) + remaining based on LCC 5, T14 As per recommended package of practices (50% N as basal, remaining 50% at 30 days after sowing).The treatments were replicated thrice in a randomized block design. The results recorded during the year indicated that production of fodder maize was better with the treatment T13 (150 kg N/ha (40% N basal) + remaining based on LCC 5. It recorded 470.01 q green and 135.02 q dry matter yield per hectare. The growth parameters namely; plant height; number of leaves per plant and quality were also improved with this treatment as compared to other treatments.

Effect of Vermicompost Enriched with Biofertilizers, Bioagents and Micronutrients on Growth and Yield of Groundnut (Arachis hypogaea L.)

Aims: To study the response of groundnut (Arachis hypogaea L.) to vermicompost enriched with biofertilizers, bioagents and micronutrients. Study Design: Field experiment was conducted at Junagadh (Gujarat) with ten treatments comprising of vermicompost enriched with biofertilizers, bioagents and micronutrients viz., Absolute Control (T1), 100% Recommended dose of fertilizers (T2), Vermicompost 2 t/ha (T3), Vermicompost 2 t/ha + Biofertilizers (Rhizobium Bradyrhizobium japonicum + Phosphate Solubilizing Bacteria Bacillus subtilis + Potash Solubilizing Bacteria Frateuria aurantia each at 2 L/ha) (T4), Vermicompost 2 t/ha + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha (T5), Vermicompost 2 t/ha + Beauveria bassiana 3 kg/ha (T6), Vermicompost 2 t/ha + Biofertilizers (Rhizobium + Phosphate Solubilizing Bacteria + Potash Solubilizing Bacteria each 2 L/ha) + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha + Beauveria bassiana 3 kg/ha (T7), Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha (T8), Vermicompost 2 t/ha + Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha (T9) and Vermicompost 2 t/ha + Biofertilizers (Rhizobium + Phosphate Solubilizing Bacteria + Potash Solubilizing Bacteria each 2 L/ha) + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha + Beauveria bassiana 3 kg/ha + Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha (T10) in Randomized Block Design with three replications. Place and Duration of the Study: Instructional Farm, Department of Agronomy, College of Agriculture, Junagadh Agricultural University, Junagadh (Gujarat) during kharif seasons of 2019 and 2020. Methodology: Five plants were selected randomly from each net experimental plot and tagged. Growth parameters viz., plant height, number of branches, SPAD meter reading and number of root nodules, and yield attributes viz., number of mature pods per plant and pods weight per plant were recorded from that tagged plants and their average was considered for final record. Pod yield and haulm yield were recorded from net plot size of each experiment plot and converted in to hectare base. Shelling percentage was counted on the basis of 150 g pod sample taken randomly from net plot produce. Results: The results indicated that the highest plant height (35.64 cm), number of branches per plant (8.11), number of root nodules per plant (154.5) at 45 days after sowing (DAS), dry weight of root nodules per plant at 45 DAS (0.982 g), Soil Plant Analysis Development (SPAD) meter reading at 45 DAS (39.09), number of mature pods per plant (18.40), pod weight per plant (15.37 g), 100-kernel weight (44.08 g) and shelling percentage (73.16%) with the highest pod yield (2.305 t/ha) and haulm yield (3.889 t/ha) were achieved by application of Vermicompost 2 t/ha + Biofertilizers (Rhizobium + Phosphate Solubilizing Bacteria + Potash Solubilizing Bacteria each 2 L/ha) + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha + Beauveria bassiana 3 kg/ha + Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha, which is considered the more effective application among all treatments improves growth, pod and haulm yield of groundnut under clay soil conditions.

Feasibility Study of Using Absolute SPAD Values for Standardized Evaluation of Corn Nitrogen Status

Nitrogen fertilizer recommendations for corn (Zea mays L.) should ensure high yields using adequate N doses. Soil–plant analysis development (SPAD) meter technology using absolute SPAD values, might be more reliable than relative SPAD values in helping corn producers making timely decisions about N applications. This study aimed to develop a relationship between absolute SPAD values and leaf N concentration, and to determine optimal leaf N concentrations at early corn growth stages (V6, V8, V10, and V12). Three experiments were conducted during two summer seasons (2014 and 2015) using six N treatments applied at early corn growth stages. In parallel, two experiments were carried out in a high residual N environment to establish the optimum corn leaf N concentration. Results showed a significant linear relationship between corn leaf N concentrations and absolute SPAD values (R2 = 0.80, p < 0.05). The mean optimum corn leaf N concentration decreased over corn growth stages. It is of great importance to make the absolute SPAD method accessible for farmers, but more research is required to perform standardized reading of absolute SPAD values data.

Effect of Real time nitrogen management on yield attributes of direct seeded rice by using SPAD meter and Greenseeker

A field experiment was conducted during Kharif 2018, laid out in Randomized Block Design with three replications having seven treatments viz. N omission (T1), N applied as basal and AT (T2), N as basal, AT and PI (T3), N as basal and top dressing at NDVI threshold of 0.75 (T4), at NDVI threshold of 0.8 (T5), at SPAD threshold of 35.0 (T6) and SPAD threshold of 37.5 (T7) with Rice variety Sahabhagidhan.The study revealed that application of 30 kg N/ha as basal dose and top dressing of 20 kg N/ha twice at 35 and 63 DAS guided by NDVI threshold value of 0.8 (T5) was found to be superior over other treatments with respect to productivity. T5 recorded highest grain yield of 4438 kg/ha which was 17.0% higher than that top dressed at NDVI threshold of 0.75 (T4) and 7.1% higher than that top dressed at SPAD threshold value of 37.5 (T7). In case of SPAD meter, nitrogen top dressed at threshold value of 37.5 (T7) produced grain yield of 4143 kg/ha which was 15.0% higher than T6. T5 produced maximum dry matter of 8678 kg/ha with highest grain yield (4438 kg/ha), straw yield (5092 kg/ha) and harvest index 46.0%.

Prediction of spring maize yields using leaf color chart, chlorophyll meter, and GreenSeeker optical sensor

Summary Predicting in-season crop yield is a unique tool for drawing important crop management decisions for precision farming. Field experiments were conducted at two locations in northwestern India under different agro-climatic zones to predict and validate spring maize yield using various in-season spectral indices. The spectral properties measured with leaf color chart (LCC), chlorophyll meter (SPAD meter), and GreenSeeker optical sensor were used to predict grain yield. A power function based on the Normalized Difference Vegetative Index (NDVI) measured with GreenSeeker optical sensor at V9 growth stage (9th leaf with fully exposed collar) presented higher values of coefficient of determination and explained 61% of the variability in spring maize grain yield, whereas NDVI measured at early and late growth stages were not reliable for the purpose. The spectral properties recorded with the SPAD meter and LCC rendered better grain yield estimates at VT growth stage (tasseling) and were respectively able to explain 75 and 76% variability in grain yield. The developed models were validated on an independent data set from another field experiment on spring maize. The normalized root mean square error (NRMSE) was <10% for LCC and SPAD at all the growth stages and at V9 growth stage for NDVI. The LCC, SPAD, and NDVI values adjusted with cumulative growing degree day were not helpful to improve NRMSE.

Growth of Transplanted Rice as Influenced by Enriched Nitrogen Sources at Different Levels

The field experiment was carried out during kharif, 2018 at the research farm of the ICAR, Indian Institute of Rice Research (IIRR), Hyderabad (TS) to study the growth of transplanted rice as influenced by the enriched nitrogen sources at different levels. The experiment was laid out in randomized block design with eleven treatments viz., T1 Control (0:60:40 kg N:P:K ha-1), T2 (75% Recommended Dose of Nitrogen (RDN) through neem coated urea), T3 (75% RDN through enriched rice straw compost with trichoderma), T4 (75% RDN through vermicompost), T5 (75% RDN through neem coated urea + nitrification inhibitor), T6 (75% RDN (50% RDN through vermicompost + 25% RDN through neem coated urea + nitrification inhibitor ), T7 (100% RDN through neem coated urea), T8 (100% RDN through enriched rice straw compost with trichoderma), T9 (100% RDN through vermicompost), T10 (100% RDN through neem coated urea + nitrification inhibitor) and T11 (100% RDN (50% RDN through vermicompost + 50% RDN through neem coated urea + nitrification inhibitor). From this study it can be concluded that application of 100% RDN through neem coated urea resulted in highest plant height at 90 Days after transplanting (DAT) and at harvest, tillers m-2 at 60 DAT and at harvest, dry matter production at 90 DAT and at harvest, SPAD meter readings at 60 DAT and 90 DAT. Similarly, lowest plant height, tillers m-2, dry matter production and SPAD meter readings were recorded for control.