VARIABILITY OF RICE YIELD WITH RESPECT TO CROP HEALTH

Chlorophyll content of leaf can be used as an indicator of the crop health. The SPAD chlorophyll meter has been acceptably used for rapid analysis of chlorophyll content and nitrogen status of crops while it has not been established how strongly the SPAD values are correlated with rice yield within a plot. This study was to explore the relationship between rice yields and the leaf SPAD value of the associated rice plots. Twenty sampling points of rice leaves plant were taken at three difference growing stages based on grid point sampling of 30m x 18m for two crop seasons. Two methods, namely instantaneous yield from on-board yield monitoring system mounted on a combine harvester and estimated crop yield from cutting test (CCT) yield were used to measure the variability of harvested rice yield within the rice plot. The SPAD values were found positively correlated with grain yield at different growth stages. The highest significant correlation was at crop age 70 days after planting with Pearson’s correlations (r) ranging 0.7280 to 0.8336 (P<0.001). Consequently, information with regards to SPAD value variability could triggers farmers in taking immediate in situ action for improving the crop yield while information with regards to crop yield variability could assist farmers in planning the proper farming practice for the subsequent cropping seasons. Generally, this available technology would assist farmers in improving their crop yield and their economic status.

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Chlorophyll Content in Leaves of Wheat as Influenced by Inorganic, Organic and Integrated Sources of Nutrient Application

International Journal of Plant & Soil Science ◽

10.9734/ijpss/2021/v33i230412 ◽

2021 ◽

pp. 31-45

Author(s):

Megha Vishwakarma ◽

P. S. Kulhare ◽

G. S. Tagore

Keyword(s):

Chlorophyll Content ◽

Chlorophyll A ◽

Field Experiments ◽

Winter Season ◽

Leaf Tissue ◽

Coefficient Of Determination ◽

Growth Stages ◽

Total Chlorophyll ◽

Pooled Data ◽

Spad Value

Field experiments were conducted during winter season of 2018-19 and 2019-20 with three sources of nutrient viz., inorganic, organics (FYM, VC and biofertilizers) and their integration as main treatments and five levels [S1-0 (0-0-0 kg NPK ha-1), S2-100% (120-60-40 kg NPK ha-1), S3-150% (180-90-60 kg NPK ha-1), S4-200% (240-120-80 kg NPK ha-1) and S5-Soil Test based (STV) NPK i.e. 149-176-33 kg ha-1 in split plot design with three replications. The chlorophyll content (‘a’, ‘b’ and total) in leaves and Soil Plant Analyzer Development (SPAD) value were recorded at crown root initiation (CRI), tillering, jointing and milking stage of wheat. The pooled data of findings revealed that the treatment with inorganic sources showed significant increase in the SPAD readings (9.62, 15.54, 23.77 and 29.83), chlorophyll ‘a’ (0.76, 0.83, 1.47 and 0.63 mg g-1 leaf tissue), ‘b’ (0.44, 0.78, 0.87 and 0.57 mg g-1 leaf tissue) and total (1.19, 1.64, 2.25 and 1.14 mg g-1 leaf tissue) chlorophyll content in leaves over organic source at all the growth stages. All the levels of nutrient were significantly increased the chlorophyll content and SPAD value over control at all the stages except chlorophyll ‘a’ at jointing and milking stage. However, amongst the levels 150% and 200% NPK were found significantly superior to 100% NPK for SPAD value (8.32 and 8.71 at CRI and 12.56 and 12.19 at tillering), chlorophyll ‘a’ (0.73 and 0.70 mg g-1 leaf tissue at CRI), chlorophyll ‘b’ (0.46 and 0.45 mg g-1 leaf tissue at CRI, 0.68 and 0.71 mg g-1 leaf tissue at tillering and 0.53 and 0.59 mg g-1 leaf tissue at milking), respectively. The interaction results suggested that the 200% NPK with inorganic and integrated sources significantly superior to 100% NPK for chlorophyll ‘a’ content at jointing and milking stage. The application of 150% and 200% NPK with inorganic source were found significantly higher over the same level of NPK with integrated source of nutrient for total chlorophyll content and SPAD value at all the growth stages except 150% NPK for total chlorophyll at jointing and milking stage and SPAD value at milking stage. The correlation between SPAD value and chlorophyll ’a’, ‘b’, total were found significantly and positively at all growth stages. Coefficient of determination values between SPAD and chlorophyll content showed linear relationship at all the growth stages.

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Using UAV Collected RGB and Multispectral Images to Evaluate Winter Wheat Performance across a Site Characterized by Century-Old Biochar Patches in Belgium

Remote Sensing ◽

10.3390/rs12152504 ◽

2020 ◽

Vol 12 (15) ◽

pp. 2504 ◽

Cited By ~ 2

Author(s):

Ramin Heidarian Dehkordi ◽

Victor Burgeon ◽

Julien Fouche ◽

Edmundo Placencia Gomez ◽

Jean-Thomas Cornelis ◽

...

Keyword(s):

Winter Wheat ◽

Crop Yield ◽

Positive Impact ◽

Crop Growth ◽

Wheat Crop ◽

P Value ◽

Growth Stages ◽

Crop Performance ◽

Crop Health

Remote sensing data play a crucial role in monitoring crop dynamics in the context of precision agriculture by characterizing the spatial and temporal variability of crop traits. At present there is special interest in assessing the long-term impacts of biochar in agro-ecosystems. Despite the growing body of literature on monitoring the potential biochar effects on harvested crop yield and aboveground productivity, studies focusing on the detailed crop performance as a consequence of long-term biochar enrichment are still lacking. The primary objective of this research was to evaluate crop performance based on high-resolution unmanned aerial vehicle (UAV) imagery considering both crop growth and health through RGB and multispectral analysis, respectively. More specifically, this approach allowed monitoring of century-old biochar impacts on winter wheat crop performance. Seven Red-Green-Blue (RGB) and six multispectral flights were executed over 11 century-old biochar patches of a cultivated field. UAV-based RGB imagery exhibited a significant positive impact of century-old biochar on the evolution of winter wheat canopy cover (p-value = 0.00007). Multispectral optimized soil adjusted vegetation index indicated a better crop development over the century-old biochar plots at the beginning of the season (p-values < 0.01), while there was no impact towards the end of the season. Plant height, derived from the RGB imagery, was slightly higher for century-old biochar plots. Crop health maps were computed based on principal component analysis and k-means clustering. To our knowledge, this is the first attempt to quantify century-old biochar effects on crop performance during the entire growing period using remotely sensed data. Ground-based measurements illustrated a significant positive impact of century-old biochar on crop growth stages (p-value of 0.01265), whereas the harvested crop yield was not affected. Multispectral simplified canopy chlorophyll content index and normalized difference red edge index were found to be good linear estimators of harvested crop yield (p-value(Kendall) of 0.001 and 0.0008, respectively). The present research highlights that other factors (e.g., inherent pedological variations) are of higher importance than the presence of century-old biochar in determining crop health and yield variability.

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Monitoring the Vertical Distribution of Maize Canopy Chlorophyll Content Based on Multi-Angular Spectral Data

Remote Sensing ◽

10.3390/rs13050987 ◽

2021 ◽

Vol 13 (5) ◽

pp. 987

Author(s):

Bin Wu ◽

Huichun Ye ◽

Wenjiang Huang ◽

Hongye Wang ◽

Peilei Luo ◽

...

Keyword(s):

Remote Sensing ◽

Vertical Distribution ◽

Chlorophyll Content ◽

Spectral Data ◽

Growth Stage ◽

Growth Stages ◽

Growth Monitoring ◽

Spad Value ◽

The Vertical Distribution ◽

Late Growth

Remote sensing approaches have several advantages over traditional methods in determining information on physical and chemical parameters, including timely data acquisition, low costs, and wide coverage. Thus, remote sensing is widely used in crop growth monitoring. Unlike vertical observations, multi-angular remote sensing technology can obtain the vertical distribution information of the central and lower leaves of a crop. Furthermore, applications of remote sensing on the vertical distribution of maize canopy components is complicated, and related research is limited. In the current paper, we employed multi-angular spectral data, measured by a self-designed multi-angular observation instrument at view zenith angles (VZAs) of 0°, 10°, 20°, 30°, 40°, 50°, and 60°, to explore the monitoring strategy and monitoring precision of the vertical distribution of chlorophyll content in the maize canopy. This was then used to determine the optimal monitoring method for the chlorophyll content (soil and plant analyzer development (SPAD) value) of each layer. The correlation between SPAD value and chlorophyll sensitivity indices at different growth stages was used as the basis for screening indices and VZAs. The correlation between the selected EPI (eucalyptus pigment index) and REIP (red edge inflection point) indices and chlorophyll content indicated view zenith angles (VZAs) of 0°, 30°, and 40° as optimal for the early growth stage monitoring of chlorophyll content in the 1st, 2nd, and 3rd layers, respectively. These values were associated with RMSEs of 4.14, 1.71, and 1.11 for EPI, respectively; and 4.61, 2.31, and 1.00 for REIP, respectively. In addition, a VZA of 50° was selected to monitor the chlorophyll content of the 1st, 2nd, 3rd, and 4th layers at the late growth stage, with RMSE values of 2.97, 3.50, 2.80, and 4.80 for EPI, respectively; and 3.16, 5.02, 4.55, and 7.85 for REIP, respectively. The results demonstrated the ability of canopy multi-angular spectral reflectance to accurately estimate the maize canopy chlorophyll content vertical distribution, with the VZAs of different vertical layers varying between the early and late growth stages.

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Evaluation of weed control in acetyl coA carboxylase-resistant rice with mixtures of quizalofop and auxinic herbicides

Weed Technology ◽

10.1017/wet.2019.134 ◽

2019 ◽

Vol 34 (4) ◽

pp. 498-505

Author(s):

Tameka L. Sanders ◽

Jason A. Bond ◽

Benjamin H. Lawrence ◽

Bobby R. Golden ◽

Thomas W. Allen ◽

...

Keyword(s):

Weed Control ◽

Rice Yield ◽

Field Studies ◽

Growth Stages ◽

Acetyl Coa Carboxylase ◽

Acetyl Coa ◽

Herbicide Treatments ◽

Herbicide Mixture ◽

Sequential Treatments ◽

And Control

AbstractRice with enhanced tolerance to herbicides that inhibit acetyl coA carboxylase (ACCase) allows POST application of quizalofop, an ACCase-inhibiting herbicide. Two concurrent field studies were conducted in 2017 and 2018 near Stoneville, MS, to evaluate control of grass (Grass Study) and broadleaf (Broadleaf Study) weeds with sequential applications of quizalofop alone and in mixtures with auxinic herbicides applied in the first or second application. Sequential treatments of quizalofop were applied at 119 g ai ha−1 alone and in mixtures with labeled rates of auxinic herbicides to rice at the two- to three-leaf (EPOST) or four-leaf to one-tiller (LPOST) growth stages. In the Grass Study, no differences in rice injury or control of volunteer rice (‘CL151’ and ‘Rex’) were detected 14 and 28 d after last application (DA-LPOST). Barnyardgrass control at 14 and 28 DA-LPOST with quizalofop applied alone or with auxinic herbicides EPOST was ≥93% for all auxinic herbicide treatments except penoxsulam plus triclopyr. Barnyardgrass control was ≥96% with quizalofop applied alone and with auxinic herbicides LPOST. In the Broadleaf Study, quizalofop plus florpyrauxifen-benzyl controlled more Palmer amaranth 14 DA-LPOST than other mixtures with auxinic herbicides, and control with this treatment was greater EPOST compared with LPOST. Hemp sesbania control 14 DA-LPOST was ≤90% with quizalofop plus quinclorac LPOST, orthosulfamuron plus quinclorac LPOST, and triclopyr EPOST or LPOST. All mixtures except quinclorac and orthosulfamuron plus quinclorac LPOST controlled ivyleaf morningglory ≥91% 14 DA-LPOST. Florpyrauxifen-benzyl or triclopyr were required for volunteer soybean control >63% 14 DA-LPOST. To optimize barnyardgrass control and rice yield, penoxsulam plus triclopyr and orthosulfamuron plus quinclorac should not be mixed with quizalofop. Quizalofop mixtures with auxinic herbicides are safe and effective for controlling barnyardgrass, volunteer rice, and broadleaf weeds in ACCase-resistant rice, and the choice of herbicide mixture could be adjusted based on weed spectrum in the treated field.

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Genetic dissection of chlorophyll content at different growth stages in common wheat

Journal of Genetics ◽

10.1007/s12041-009-0026-x ◽

2009 ◽

Vol 88 (2) ◽

pp. 183-189 ◽

Cited By ~ 19

Author(s):

Kunpu Zhang ◽

Zhijun Fang ◽

Yan Liang ◽

Jichun Tian

Keyword(s):

Chlorophyll Content ◽

Common Wheat ◽

Growth Stages ◽

Genetic Dissection ◽

Different Growth Stages

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Evaluation of Harvest-Aid Herbicides as Desiccants in Lentil Production

Weed Technology ◽

10.1614/wt-d-16-00007.1 ◽

2016 ◽

Vol 30 (3) ◽

pp. 629-638 ◽

Cited By ~ 5

Author(s):

Ti Zhang ◽

Eric N. Johnson ◽

Christian J. Willenborg

Keyword(s):

Adverse Effects ◽

Crop Yield ◽

Seed Yield ◽

Yield Loss ◽

Field Trials ◽

Growth Stages ◽

Yield And Quality ◽

Seed Field ◽

Dry Down ◽

General Reduction

Desiccants are currently used to improve lentil dry-down prior to harvest. Applying desiccants at growth stages prior to maturity may result in reduced crop yield and quality, and leave unacceptable herbicide residues in seeds. There is little information on whether various herbicides applied alone or as a tank-mix with glyphosate have an effect on glyphosate residues in harvested seed. Field trials were conducted at Saskatoon and Scott, Saskatchewan, Canada, from 2012 to 2014 to determine whether additional desiccants applied alone or tank mixed with glyphosate improve crop desiccation and reduce the potential for unacceptable glyphosate residue in seed. Glufosinate and diquat tank mixed with glyphosate were the most consistent desiccants, providing optimal crop dry-down and a general reduction in glyphosate seed residues without adverse effects on seed yield and weight. Saflufenacil provided good crop desiccation without yield loss, but failed to reduce glyphosate seed residues consistently. Pyraflufen-ethyl and flumioxazin applied alone or tank mixed with glyphosate were found to be inferior options for growers as they exhibited slow and incomplete crop desiccation, and did not decrease glyphosate seed residues. Based on results from this study, growers should apply glufosinate or diquat with preharvest glyphosate to maximize crop and weed desiccation, and minimize glyphosate seed residues.

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Effect of fungicides on the enzymatic activity of the antioxidant system and the chlorophyll content in lupine plants during seed dressing

Karantin i zahist roslin ◽

10.36495/2312-0614.2020.7-9.3-6 ◽

2020 ◽

pp. 3-6

Author(s):

O. Borzykh ◽

O. Tsurkan ◽

L. Chervyakova ◽

T. Panchenko

Keyword(s):

Analytical Chemistry ◽

Chlorophyll Content ◽

Peroxidase Activity ◽

Catalase Activity ◽

Control Level ◽

Growth Stages ◽

Enzymatic System ◽

Initial Growth ◽

Seed Dressing ◽

Catalase Peroxidase

Goal. The effect of fungicides on the dynamics of the activity of peroxidase, catalase (CAT) and chlorophyll content in lupine plants during seed dressing has been established. Methods. Laboratory and vegetation researches were conducted in the laboratory of analytical chemistry of pesticides of the Institute of Plant Protection. Yellow lupine (Lupinus luteus L.), variety Obriy has been grown. The objects of research were fungicides triticonazol (40 g/t) and its combination with prochloraz (120 g/t). Determination of the content of fungicides in plants was carried out using chromatographic methods according to officially approved methods and methods developed in the laboratory of analytical chemistry of pesticides. Chlorophyll content and peroxidase activity were measured by colorimetric method, catalase activity — by titrimetric method. Results. According to the research results, the varying sensitivity of the enzymatic system of antioxidant defense (catalase, peroxidase) in response to seed dressing by fungicides was recorded. It showed that on the 10th day after sowing, content of triticonazol in plants was 0.8 mg/kg, and the peroxidase activity was similar to that in untreated plants. Subsequently, against the background of a decrease in the content of the active substance, a gradual activation of the enzyme was observed. Catalase activity also gradually increased beginning from the 14th day, and on the 30th day it exceeded the corresponding control indicator by 40%. When using a combination of triticonazol with prochloraz, the disturbance in the balance of peroxidase catalase was more significant. However, by the phase of 7—8 leaves, with a minimal total content of fungicides (0.38 mg/kg), the enzyme activity approached the control level, which is associated with the restoration of plant homeostasis and the formation of its adaptive potential under stress conditions. The stimulating effect of these fungicides on chlorophyll content at the initial growth stages of lupine was established. The chlorophyll concentration in fungicides-treated plants exceeded the control indicator by 11—29%. Conclusions. The use of systemic triazole fungicides to protect seedlings, improves the photosynthetic activity of plants and at the same time acts as a stress factor that activates protecting enzymes (catalase, peroxidase), which trigger the development of protective adaptive reactions of plants.

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Differential Tolerance of Clearfield Rice Cultivars to Imazamox

Weed Technology ◽

10.1614/wt-d-10-00129.1 ◽

2011 ◽

Vol 25 (2) ◽

pp. 192-197 ◽

Cited By ~ 17

Author(s):

Jason A. Bond ◽

Timothy W. Walker

Keyword(s):

Growth Stage ◽

Rice Yield ◽

Field Studies ◽

First Year ◽

Growth Stages ◽

Rice Cultivars ◽

Rough Rice ◽

Rice Yields ◽

Clearfield Rice ◽

Two Hybrid

Field studies were conducted to compare the response of one inbred (‘CL161’) and two hybrid (‘CLXL729’ and ‘CLXL745’) Clearfield (CL) rice cultivars to imazamox. Imazamox was applied at 44 and 88 g ai ha−1to rice in the panicle initiation (PI) and PI plus 14 d (PI + 14) growth stages and at 44 g ha−1to rice in the midboot growth stage. Maturity of hybrid CL cultivars was delayed following imazamox at 44 g ha−1applied at PI + 14 and midboot. Furthermore, imazamox at 44 g ha−1, applied at midboot, delayed maturity of CLXL745 more than CLXL729. Expressed as a percentage of the weed-free control plots, rough rice yields for CLXL729 were 91% following imazamox at 44 g ha−1applied at PI + 14, 78% following imazamox at 44 g ha−1applied at midboot, and 77% for imazamox at 88 g ha−1applied at PI + 14. Rough rice yield for CLXL745 was 77 to 92% of the control following all imazamox treatments. All imazamox treatments reduced CLXL745 rough rice yield compared with CL161. Rough rice yield, pooled across CL cultivar, varied with imazamox treatment between years, and these differences may have been a consequence of lower temperatures and solar radiation in the first year. Hybrid CL cultivars CLXL729 and CLXL745 were less tolerant than was CL161 when imazamox was applied at nonlabeled rates (88 g ha−1) and/or timings (PI + 14 or midboot). Because of variability in rice growth stages and irregularities in imazamox application in commercial fields, inbred CL cultivars should be planted where an imazamox application will likely be required.

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Multi-Spatial Resolution Satellite and sUAS Imagery for Precision Agriculture on Smallholder Farms in Malawi

Photogrammetric Engineering & Remote Sensing ◽

10.14358/pers.86.2.107 ◽

2020 ◽

Vol 86 (2) ◽

pp. 107-119 ◽

Cited By ~ 1

Author(s):

Brad G. Peter ◽

Joseph P. Messina ◽

Jon W. Carroll ◽

Junjun Zhi ◽

Vimbayi Chimonyo ◽

...

Keyword(s):

Chlorophyll Content ◽

Precision Agriculture ◽

Strongly Correlated ◽

Multispectral Images ◽

Green Band ◽

Smallholder Farms ◽

On Farm ◽

Linear Regressions ◽

Crop Health ◽

Sentinel 2

A collection of spectral indices, derived from a range of remote sensing imagery spatial resolutions, are compared to on-farm measurements of maize chlorophyll content and yield at two trial farms in central Malawi to evaluate what spatial resolutions are most effective for relating multispectral images with crop status. Single and multiple linear regressions were tested for spatial resolutions ranging from 7 cm to 20 m using a small unmanned aerial system (<small>sUAS</small>) and satellite imagery from Planet, <small>SPOT</small> 6, Pléiades, and Sentinel-2. Results suggest that imagery with spatial resolutions nearer the maize plant scale (i.e., 14–27 cm) are most effective for relating spectral signals with crop health on smallholder farms in Malawi. Consistent with other studies, green-band indices were more strongly correlated with maize chlorophyll content and yield than conventional red-band indices, and multivariable models often outperformed single variable models.

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Nitrogen fertilizer programs following rice exposure to a sub-lethal concentration of paraquat

Weed Technology ◽

10.1017/wet.2020.62 ◽

2020 ◽

Vol 34 (6) ◽

pp. 807-813

Author(s):

Benjamin H. Lawrence ◽

Jason A. Bond ◽

Bobby R. Golden ◽

Thomas W. Allen ◽

Daniel B. Reynolds ◽

...

Keyword(s):

Rice Yield ◽

Management Strategies ◽

Dry Weight ◽

N Fertilizer ◽

Lethal Concentration ◽

Growth Stages ◽

Fertilizer Management ◽

Starter Fertilizer ◽

Rough Rice ◽

Reduced Height

AbstractOff-target paraquat movement to rice has become a major problem in recent years for rice producers in the midsouthern United States. Nitrogen (N) fertilizer is applied to rice in greater quantity and frequency than all other nutrients to optimize rice yield. Two separate field studies were conducted from 2015 to 2018 in Stoneville, MS, to assess whether starter N fertilizer can aid rice recovery from exposure to a sub-lethal concentration of paraquat and to evaluate rice response to different N fertilizer management strategies following exposure to a sub-lethal concentration of paraquat. In both studies, paraquat treatments consisted of paraquat at 0 and 84 g ai ha–1 applied to rice in the two- to three-leaf (EPOST) growth stage. In the starter fertilizer study, N fertilizer at 24 kg ha–1 as ammonium sulfate (AMS) was applied to rice at spiking- to one-leaf (VEPOST), two- to three-leaf (EPOST), or three- to four-leaf (MPOST) growth stages before and after paraquat treatment. In the N fertilizer timing study, N fertilizer at 168 kg N ha–1 was applied in a single four-leaf to one-tiller (LPOST) application or two-, three-, and two four-way split applications. Despite starter N fertilizer applications, paraquat injured rice ≥41%, reduced height 57%, reduced dry weight prior to flooding 77%, delayed maturity 10 d, reduced dry weight at maturity 33%, and reduced rough rice yield 35% in the starter fertilizer study. Similarly, in the N fertilizer timing study, paraquat injured rice ≥45%, reduced height 14%, delayed maturity 10 d, reduced dry weight at maturity 44%, and reduced rough rice yield 50% for all N fertilizer management strategies. Both studies indicate that severe complications in growth and development can occur from rice exposure to a sub-lethal concentration of paraquat. In both studies, manipulation of N fertilizer management did not facilitate rice recovery from early-season exposure to paraquat.

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