Cotton Growth Stages Research Articles

Poultry Litter Placement Effects on Cotton Seedling Emergence and Early Growth

Core Ideas Sowing into poultry litter bands inhibits seed emergence and root establishment. Aboveground plant production during early cotton growth stages may be negatively impacted by sowing into poultry litter bands. Banding poultry litter beside crop rows may be an effective fertilizer management strategy. Interest in using poultry litter (PL) as a nutrient source for row crop production has increased in the southeastern United States. Poultry litter is generally broadcasted on the soil surface. This practice exposes N to volatilization and P to loss with surface water runoff, which potentially negatively impacts the environment. Placing PL in narrow bands below the soil surface has been shown to reduce such losses and improve crop yield, but the influence of band placement on seedling emergence and growth is not well understood. A glasshouse experiment was conducted with a Marvyn loamy sand to determine the effects of PL placement on emergence and early growth of cotton (Gossypium hirsutum L.). Poultry litter placement was compared with ammonium sulfate (AS); both were applied at a rate of 112 kg N ha−1. The PL and AS treatments consisted of surface broadcasting, banding 5 cm below or to the side of seed, seeding directly in bands, and an unfertilized control. Banding 5 cm to the side of seeds produced emergence rates, plant biomass, leaf area, leaf chlorophyll content, and root morphological parameters similar to those of the control and surface broadcast treatments for cotton fertilized with AS and PL. However, seeds placed directly in PL or AS bands had the lowest emergence rate and growth parameters. Therefore, banding PL 5 cm or more to the side of seeds may be an effective fertilizer management strategy for cotton production.

Spatio-temporal monitoring of cotton cultivation using ground-based and airborne multispectral sensors in GIS environment.

Multispectral sensor capability of capturing reflectance data at several spectral channels, together with the inherent reflectance responses of various soils and especially plant surfaces, has gained major interest in crop production. In present study, two multispectral sensing systems, a ground-based and an aerial-based, were applied for the multispatial and temporal monitoring of two cotton fields in central Greece. The ground-based system was Crop Circle ACS-430, while the aerial consisted of a consumer-level quadcopter (Phantom 2) and a modified Hero3+ Black digital camera. The purpose of the research was to monitor crop growth with the two systems and investigate possible interrelations between the derived well-known normalized difference vegetation index (NDVI). Five data collection campaigns were conducted during the cultivation period and concerned scanning soil and plants with the ground-based sensor and taking aerial photographs of the fields with the unmanned aerial system. According to the results, both systems successfully monitored cotton growth stages in terms of space and time. The mean values of NDVI changes through time as retrieved by the ground-based system were satisfactorily modelled by a second-order polynomial equation (R 2 0.96 in Field 1 and 0.99 in Field 2). Further, they were highly correlated (r 0.90 in Field 1 and 0.74 in Field 2) with the according values calculated via the aerial-based system. The unmanned aerial system (UAS) can potentially substitute crop scouting as it concerns a time-effective, non-destructive and reliable way of soil and plant monitoring.

Genome-wide characterization of the Rab gene family in Gossypium by comparative analysis

BackgroundRab protein family is the largest subfamily of small G protein family. As one of the most important families in plant, Rab family plays an important role in the process of plant growth and development. So far, the identification of 57 members of the Rab family in Arabidopsis has been completed. In cotton, the relevant family has not been reported.ResultsHere, we identified 87, 169, 136, 80 Rabs in the four sequenced cotton species, G. raimondii (D5), G. hirsutum acc. TM-1 (AD1), G. barbadense acc. 3-79 (AD2) and G. arboreum (A2), respectively. Biological information analysis showed that the number of amino acid is 200–300 aa among Rab family members in G. raimondii and the protein molecular weight is between 20 and 30 kDa, which is consistent with the characterization of the Rab protein itself. 87 GrRabs in G. raimondii are divided into eight groups. In each group, intron numbers and subcellular localization of Rab protein are basically the same. We mapped the distribution of GrRab genes on 13 chromosomes of G. raimondii except two genes. Among the 87 GrRabs in G. raimondii, we identified 60 pairs of GrRabs formed in whole genome duplication. Among all the gene pairs, the Ka/Ks values were less than 1. This indicates that it is the results of the purification selection and will help maintain the conservation of gene in structure and function. Further, 4 of the 87 GrRabs showed tandem duplication. They were GrRabA2a vs GrRabD1a and GrRabA2h vs GrRabD1b respectively. Expression patterns analysis of 169 GhRabs in G. hirsutum acc. TM-1 indicates that most Rab family members play a certain role in different tissues/organs and different growth stages of cotton, implying their potential function in the polar growth of pollen tube, root hair and fiber cell, as well as improving stress and disease tolerance.ConclusionThe systematic investigation of Rab genes in cotton will lay a foundation for understanding the functional roles of different Rab members in the polar growth and stress tolerance.

Resistance of Enlist™(AAD-12) Cotton to Glufosinate

Enlist™ cotton contains theaad-12andpatgenes that confer resistance to 2,4-D and glufosinate, respectively. Thirty-three field trials were conducted focused on Enlist cotton injury from glufosinate as affected by cotton growth stage, application rate, and single or sequential applications. Maximum injury from a single application of typical 1X (542 g ae ha-1) and 2X use rates was 3 and 13%, respectively, regardless of growth stage. Injury from sequential applications of 1X or 2X rates was equivalent to single applications. Similar injury was observed with four commercial formulations of glufosinate. Cotton yield was never affected by glufosinate. This research demonstrates Enlist™ cotton has robust resistance to glufosinate at rates at least twice the typical use rate when applied once or twice at growth stages ranging from 2 to 12 leaves.

Effects of low-concentration Cry1Ac toxic protein on growth and reproduction of three successive generations of Sylepta derogata population

Cotton leaf roller Sylepta derogata causes serious damage to cotton at the later growing stages of cotton. A leaf-dip method was used to measure the effects of low-concentration CrylAc toxic protein on the development and population growth of three successive generations of cotton leaf rol-lers in this study. The larval duration of Bt-fed S. derogata was 1.78-2.00 d longer, adult life span 1.44-1.94 d longer, and pupal mass 5.3%-11.8% higher than those of the control, respectively. The egg counts per female in the three generations were 65.1%, 47.3% and 37.6% higher, respectively, than those of the control, and the indexes of population trend were 11.4%, 17.5% and 20.0% greater, respectively. No significant differences were found in the duration of pupa duration, the emergence rate, the sex ratio, or the hatch rate. It was suggested that the population of cotton leaf rollers would steadily increase during the later stage of transgenic Bt cotton growth, therefore, further risk assessments of transgenic cotton and comprehensive management of these pests in cotton fields were needed.

Effect of Waterlogging Duration at Different Growth Stages on the Growth, Yield and Quality of Cotton.

In this study, a soil culture experiment was set up in barrels to investigate the effect of waterlogging duration at different growth stages on the growth, yield, and quality of cotton in the Huang-Huai Region of China during summer. The experiment was conducted at four growth stages of cotton (seedling, squaring, flowering, and boll opening), and the waterlogging duration at each stage was set to five levels (2, 4, 6, 8, and 10 d) and the waterlogging depth was 5cm. Twenty different treatment combinations were established, and one group without waterlogging throughout the whole growth period was used as the control (CK). The results showed that the waterlogging treatments at the different growth stages reduced the morphological and yield parameters of the cotton plants as well as the physiological parameters of the cotton leaves, and the extent of the reduction in these parameters increased with the extension of the waterlogging duration. The effect of waterlogging at different growth stages on the cotton decreased in the order of the flowering, squaring, seedling, and boll-opening stages, and the highest yield reduction rates for the four stages were 38.8%, 27.9%, 18.3%, and 7.6% respectively. Additionally, waterlogging decreased the quality parameters of cotton such as the upper-half mean length, uniformity index, micronaire value, elongation, yellowness, and lint percentage at the squaring, flowering, and boll-opening stages. Furthermore, at the seedling stage waterlogging for no more than 6 d allowed the morphological and yield parameters to recover in the boll-opening stage upon timely drainage, and these parameters showed no significant decreases compared with the CK level. The critical duration of waterlogging at the squaring stage was 4 d. However, at the flowering stage, even 2 d of waterlogging could lead to the stagnation of morphological development and prevent the recovery of the cotton yield to the CK level. Therefore, when waterlogging disasters occur in cotton fields, the implementation of appropriate surface and subsurface drainage schemes for the different growth stages is needed as soon as possible to mitigate the damage.

Optimizing Irrigation Rates for Cotton Production in an Extremely Arid Area Using RZWQM2-Simulated Water Stress

Abstract. Quantifying crop water demand and optimizing irrigation management practices are essential to water resource management in arid desert oases. Agricultural systems modeling can serve to develop a better understanding of the hydrologic cycle under various irrigation and climate conditions. RZWQM2-simulated water stress can be used as an indicator for irrigation scheduling but has not been applied to extremely arid zones. The objectives of this study were to (1) evaluate the performance of RZWQM2 in simulating soil moisture content and crop production in an extremely arid area and (2) develop an optimal irrigation strategy using model-simulated crop water stress. In this study, RZWQM2 hybridized with DSSAT was calibrated and validated against soil moisture, cottield, and development stage data collected from 2006 to 2013 in a flood-irrigated cotton field located in an extremely dry oasis in Cele, situated in Xinjiang, China (mean annual precipitation 37 mm). The simulated water balance was analyzed to determine the actual crop water consumption, crop water requirements, and seepage loss. Subsequently, an optimal irrigation scheme was developed using RZWQM2 by averting crop water stress from planting to 90% open boll. In comparison to similar studies, the accuracy of soil moisture content simulations was deemed acceptable based on percent bias (PBIAS < ±15%), coefficient of determination (0.378 = R2 = 0.636), Nash-Sutcliffe model efficiency (0.130 = ME = 0.557), and root mean squared error (0.022 m3 m-3 = RMSE = 0.031 m3 m-3). The model performed well in simulating cotton yield (R2 = 0.79, ME = 0.75, RMSE = 417.0 kg ha-1, and relative RMSE (rRMSE) = 12.5%). Model-simulated plant emergence dates were generally six days late because of the model’s lack of a component for mulching after seeding. Other phenological dates were closely matched, with a mean difference of ±4 days. On average, over eight years, the simulated growing season (planting to 90% open boll) water balance showed that the cotton crop consumed 532 mm year-1 of water under current irrigation practices, while 109 mm of water was lost through deep seepage. However, based on simulated PET, the crop water requirement was 641 mm year-1, suggesting water stress under current irrigation practices. Under these conditions, water stress occurred mainly during the late stages of cotton growth. The model-simulated actual evapotranspiration (ET) is comparable to the calculated ET using the water balance method, with percent error of -1.3%, indicating the rationality of applying model-simulated results in a water stress-based irrigation scheduling method. On average, the water stress-minimizing RZWQM2 irrigation schedule resulted in an apparent irrigation water savings of 32 mm year-1 (4.9%) and an annual yield increase of 527 kg ha-1 (16.3%). RZWQM2 was shown to be suitable for simulating soil hydrology and crop development in an agricultural system implemented in an extremely dry climate. Rescheduling of irrigation using a water stress-based method can be used to optimize irrigation water use and cotton production. Keywords: Cotton production, Optimum irrigation, RZWQM2, Soil water content, Water stress, WS-based regime.

Effect of sources and levels of potassium in cotton as influenced fractions of soil potassium under vertisols in Vidarbha region of Maharashtra

The present investigation was carried out in vertisols of Akola district of Maharashtra to ascertain the effect of potassium application on yield and quality of Bt cotton. This was carried out by conducting field experiments on research farm of Department of Soil Science and Agricultural Chemistry, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola and similarly on five farmer’s fields in intensive cotton growing area of vertisols in Akola district during 2012-13 and 2013-14. The treatments comprised of various levels of potassium (0, 25, 50 kg K2O ha-1) applied through either MOP or SOP and additional foliar sprays of SOP @1.5 per cent at critical growth stages of cotton alongwith addition of equivalent quantity of sulphur through bensulf and control without potassium. The fractions of soil potassium were found to be increased alongwith increasing levels of potassium. The reduction in fractions of soil potassium during peak growth stages suggests that there was highest uptake of potassium during this stage and supplemental foliar application of potassium (SOP) had significant response at critical growth stages. The vertisols of present investigation categorized as low to medium in sulphur. Application of sulphur @ 18 kg ha-1 through bensulf was also found equally beneficial as that of SOP for increasing yield. From the present investigation it can be concluded that the fractions of potassium in soil decreased at critical growth stages of cotton viz., flowering and boll development due to increasing uptake by cotton. The application of potassium @ 50 kg K2O ha-1 either through MOP or SOP irrespective of sources showed increase in soil potassium fractions and improvement in soil fertility.

Evaluation of PRE Herbicides and Seed Treatment on Thrips Infestation and Cotton Growth, Development, and Yield

The use of preemergence (PRE) herbicides may result in decreased early season cotton (Gossypium hirsutum L.) growth, which may exacerbate injury from thrips. Studies were conducted in 2013 and 2014 at the Black Belt Branch Experiment Station near Brooksville, MS; at the R.R. Foil Plant Science Research Center near Starkville, MS; and at the Delta Research and Extension Center in Stoneville, MS, to evaluate the impact of PRE herbicides and insecticide seed treatments on thrips infestations in cotton. DP 0912 B2RF was treated with thiamethoxam + fungicide, imidacloprid + fungicide, and fungicide only. All cotton seed, including the fungicide‐only treatment, were base treated with metalaxyl, pyraclostrobin, and fluxapyroxad. Preemergence herbicides included fluometuron at 1.12 kg a.i. ha−1, diuron at 1.12 kg a.i. ha−1, fomesafen at 0.28 kg a.i. ha−1, S‐metolachlor at 1.07 kg a.i. ha−1, and S‐metolachlor at 1.07 kg a.i. ha−1 + fluometuron at 1.12 kg a.i. ha−1. An untreated check was included for comparison purposes. Cotton injury from thrips was less prevalent on cotton grown from seed treated with imidacloprid. Immature thrips counts at the 4‐leaf cotton growth stage were greatest on cotton grown from seed treated with thiamethoxam, which had 136 thrips per five plants. Preemergence herbicides did not impact thrips infestations at the 2‐ or 4‐leaf cotton growth stage. No significant differences in cotton lint yield were observed due to PRE herbicide application. Seed treatments that included imidacloprid resulted in 80 kg ha−1 more lint than cotton grown from seed treated with thiamethoxam.Core Ideas Cotton seed treated with imidacloprid resulted in greater cotton yields compared with cotton grown from seed treated with thiamethoxam. Preemergence herbicide application had no impact on cotton yield. Based on these data, growers are encouraged to utilize a preemerence herbicide of their choice to manage Palmer amaranth, and imidacloprid‐based seed treatments are recommended.

Cotton Stage of Growth Determines Sensitivity to 2,4-D

The anticipated release of EnlistTM cotton, corn, and soybean cultivars likely will increase the use of 2,4-D, raising concerns over potential injury to susceptible cotton. An experiment was conducted at 12 locations over 2013 and 2014 to determine the impact of 2,4-D at rates simulating drift (2 g ae ha−1) and tank contamination (40 g ae ha−1) on cotton during six different growth stages. Growth stages at application included four leaf (4-lf), nine leaf (9-lf), first bloom (FB), FB + 2 wk, FB + 4 wk, and FB + 6 wk. Locations were grouped according to percent yield loss compared to the nontreated check (NTC), with group I having the least yield loss and group III having the most. Epinasty from 2,4-D was more pronounced with applications during vegetative growth stages. Importantly, yield loss did not correlate with visual symptomology, but more closely followed effects on boll number. The contamination rate at 9-lf, FB, or FB + 2 wk had the greatest effect across locations, reducing the number of bolls per plant when compared to the NTC, with no effect when applied at FB + 4 wk or later. A reduction of boll number was not detectable with the drift rate except in group III when applied at the FB stage. Yield was influenced by 2,4-D rate and stage of cotton growth. Over all locations, loss in yield of greater than 20% occurred at 5 of 12 locations when the drift rate was applied between 4-lf and FB + 2 wk (highest impact at FB). For the contamination rate, yield loss was observed at all 12 locations; averaged over these locations yield loss ranged from 7 to 66% across all growth stages. Results suggest the greatest yield impact from 2,4-D occurs between 9-lf and FB + 2 wk, and the level of impact is influenced by 2,4-D rate, crop growth stage, and environmental conditions.

Identification of Multiple Stress Responsive Genes by Sequencing a Normalized cDNA Library from Sea-Land Cotton (Gossypium barbadense L.)

BackgroundPlants often face multiple stresses including drought, extreme temperature, salinity, nutrition deficiency and biotic stresses during growth and development. All the stresses result in a series of physiological and metabolic reactions and then generate reversible inhibition of metabolism and growth and can cause seriously irreversible damage, even death. At each stage of cotton growth, environmental stress conditions pose devastating threats to plant growth and development, especially yield and quality. Due to the complex stress conditions and unclear molecular mechanisms of stress response, there is an urgent need to explore the mechanisms of cotton response against abiotic stresses.Methodology and Principal FindingsA normalized cDNA library was constructed using Gossypium barbadense Hai-7124 treated with different stress conditions (heat, cold, salt, drought, potassium and phosphorus deficit and Verticillium dahliae infection). Random sequencing of this library generated 6,047 high-quality expressed sequence tags (ESTs). The ESTs were clustered and assembled into 3,135 uniESTs, composed of 2,497 contigs and 638 singletons. The blastx results demonstrated 2,746 unigenes showing significant similarity to known genes, 74 uniESTs displaying significant similarity to genes of predicted proteins, and 315 uniESTs remain uncharacterized. Functional classification unveiled the abundance of uniESTs in binding, catalytic activity, and structural molecule activity. Annotations of the uniESTs by the plant transcription factor database (PlantTFDB) and Plant Stress Protein Database (PSPDB) disclosed that transcription factors and stress-related genes were enriched in the current library. The expression of some transcription factors and specific stress-related genes were verified by RT-PCR under various stress conditions.Conclusions/SignificanceAnnotation results showed that a huge number of genes respond to stress in our study, such as MYB-related, C2H2, FAR1, bHLH, bZIP, MADS, and mTERF. These results will improve our knowledge of stress tolerance in cotton. In addition, they are also helpful in discovering candidate genes related to stress tolerance. The publicly available ESTs from G. barbadense are a valuable genomic resource that will facilitate further molecular study and breeding of stress-tolerant cotton.

Effect of Liquid Mulch on the Transpiration Rate and Water Use Efficiency of Drip-irrigated Cotton

This study was carried out to address the ever severer white pollution issue in the cotton fields of arid areas and to primarily stop the increase of film residuals in cotton fields. The feasibility of replacing plastic films with liquid mulch in combination with drip irrigation was evaluated. A bucket experiment was conducted to investigate the effects of liquid mulch on the transpiration rate and water use efficiency (WUE) of drip-irrigated cottons. A total of 5 treatments were set up: liquid mulch (1900 kg/hm2) coupled with drip irrigation (LFD1), liquid mulch (2200 kg/hm2) coupled with drip irrigation (LFD2), liquid mulch (2500 kg/hm2) coupled with drip irrigation (LFD3), plastic film coupled with drip irrigation (PFD) and drip irrigation without mulch (NFD or control). The results showed that in the bud stage, the peak value of cotton leaf transpiration rate in LFD3 was 0.95 mmol•m-2•s-1 (or 21.99%) higher than that in control but 0.39 mmol•m2•s-1 (or 6.89%) lower than that in PFD. The WUE in LFD3 was the highest in any cotton growth stage among the treatments. The peak value of WUE in the seedling and bud stages was 16.90% and 15.03%, respectively higher in LFD3 than in control. When used at an appropriate dosage, liquid mulch can lower the transpiration rate and significantly raise the WUE of drip-irrigated cottons, thus paving the way towards high yields. In addition, liquid mulch has no negative effects on the soil environment and thus is of important research value and good application prospect in light of drip-irrigated cottons in arid areas.

Effects of water stress and rewatering on photosynthesis, root activity, and yield of cotton with drip irrigation under mulch

Soil water deficit is a major limitation to agricultural productivity in arid regions. Leaf photosynthesis can quickly recover after rewatering and remains at a higher level for a longer period, thus increasing crop yield and water-use efficiency (WUE). We tested our hypothesis that leaf photosynthesis and root activity of water-stressed cotton (Gossypium hirsutum L.) plants could quickly recover after rewatering at a certain growth stage and it should not influence a cotton yield but increase WUE. Treatments in this study included two degrees of water stress: mild water stress (V1) and moderate water stress (V2) imposed at one of four cotton growth stages [i.e., S1 (from the full budding to early flowering stage), S2 (from early flowering to full flowering), S3 (from full flowering to full bolling), and S4 (from full bolling to boll-opening)]. The soil water content before and after the water stress was the same as that in the control treatment (CK, 70-75% of field capacity). Water deficit significantly reduced the leaf water potential, net photosynthetic rate, and stomatal conductance in cotton. The extent of the decline was greater in S2V2 treatment compared to others. Water deficit also reduced root activity, but the extent of inhibition varied in dependence on soil depth and duration. When plants were subjected to S1V1, the root activity in the 20-100 cm depth recovered rapidly and even exceeded CK one day after rewatering. An overcompensation response was observed for both photosynthesis and aboveground dry mass within one to three days after rewatering. Compared with the CK, S1V1 showed no significant effect on the yield but it increased total WUE and irrigation WUE. These results suggest that even a short-term water stress during the S1, S2 and S4 stages mitigated, with respect to the root activity, the negative effect of drought and enhanced leaf photosynthesis compensatory effects of rewatering in order to increase cotton WUE with drip irrigation under mulch in arid areas.

Crop water use and stage-specific crop coefficients for irrigated cotton in the mid-south, United States

Regional variations in environmental conditions, cultivars, and management practices necessitate locally derived tools for crop water use estimation and irrigation scheduling. A study was conducted in northeast Louisiana (mid-south US) aimed at estimating daily crop evapotranspiration (ETc) and reference evapotranspiration (ETo) and thus, developing local crop coefficient (Kc) curves for irrigated upland cotton. ETc was determined using paired weighing lysimeters installed near the middle of a 1-ha cotton field and planted with cotton as in the rest of the surrounding field, while ETo was calculated using the Standardized Reference Evapotranspiration Equation (SREE) developed by the American Society of Civil Engineers (ASCE), using estimates of weather variables from a nearby standard reference weather station. Stage-specific Kc values averaged over 2 years were 0.42, 1.25 and 0.70 for initial, midseason, and end season stages of cotton, respectively. The initial-stage Kc value was approximately 26% lower than the Food and Agricultural Organization (FAO)-adjusted initial Kc value. The mid- and end-season Kc values obtained in the study were approximately 6% and 11% greater, respectively, than the FAO-adjusted Kc values for the corresponding stages. The observed differences among the local stage-specific Kc values (especially at initial growth stage of cotton) and the FAO-adjusted initial Kc values could be attributed to regional variations in environmental conditions, cultivars, and management practices. The ETc and Kc values obtained from this study provide research-based information for future studies and the development of Kc-based irrigation tools in this region.

A 3-year field investigation of impacts of Monsanto’s transgenic Bt-cotton NC 33B on rhizosphere microbial communities in northern China

Monsanto’s Bt-cotton NC 33B, planted in northern China for more than one decade, effectively controls cotton bollworms and decreases the use of chemical insecticides. Because of the concern about undesirable ecological side-effects of transgenic Bt-cottons, it is important to assess Bt-cotton NC 33B’s effects on soil microorganisms in this zone. Microbial communities in the rhizosphere soil of Bt and non-Bt cottons were monitored under field conditions by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprints of eubacteria, fungi and actinomycetes at six growth stages after three-year cultivation. Results showed that the population sizes and community structures of eubacteria, fungi and actinomycetes in rhizosphere soil were markedly affected by natural variations in the environment related to cotton growth stages. However, there was no significant difference in eubacterial, fungal and actinomycete population size and community structures in rhizosphere soil between NC 33B and its non-transgenic parent. In general, Bt-cotton NC 33B did not show evident effects on microbial communities in the rhizosphere soil under field conditions after three-year cultivation. This study provides a theoretical basis for environmental impact monitoring of transgenic Bt cottons.

Crop water status estimation using thermography: multi-year model development using ground-based thermal images

Thermal crop sensing technologies have potential as tools for monitoring and mapping crop water status. To create maps of water status from thermal images, a reliable relationship between direct water status measures like leaf water potential (LWP) and thermal water status measures like temperature and crop water stress index (CWSI) should be established for different crops and for different growth stages. The objective of this study was to define the relationships for cotton between LWP and CWSI derived from high-resolution ground-based thermal images and more specifically to examine whether robust relationships exist between the two measures for different varieties, through a cotton growing season, across seasons and under different geographical areas (different climate and soils). A dataset from three cotton growing seasons and from different geographical areas was built to explore the relationship between CWSI and LWP in cotton. CWSI was calculated based on ground-based thermal images and measured dry (T air + 5 °C) and wet references (Artificial wet reference surface—AWRS). A linear CWSI–LWP relationship was found with high coefficient of determination (R2 = 0.7). This relationship changed over the cotton growth stages and different CWSI–LWP relationships were established to the flowering, boll-filling and defoliation stages. The boll-filling relationship was found to be insensitive to a range of meteorological conditions. The flowering and the boll-filling models were initially validated using diagonal (oblique) thermal images from dates that were not used for calibration. For CWSI calculation, the average temperature of the lowest decile was used for the wet reference instead of the AWRS. The comparison between predicted and observed values of the validation sets yielded RMSE of 0.18 and 0.15 for the flowering and boll-filling stages, respectively. The successful use of the lowest decile as the wet reference enables a future application of the CWSI–LWP relationship to map LWP at a commercial field scale.

Productivity and quality of Bt cotton (Gossypium hirsutum) as influenced by planting geometry and nitrogen levels under irrigated and rainfed conditions

A field experiment was carried out during two consecutive kharif seasons of 2009 and 2010 at research farm of Department of Agronomy, Marathwada Krishi Vidyapeeth, Parbhani to evaluate the effect of planting geometry and different nitrogen levels on productivity and quality of Bt-cotton (Gossypium hirsutum L.) under irrigated and rainfed conditions. The results reveals that, Bt cotton sown under irrigated condition (irrigation applied at three critical growth stages of cotton) significantly improved the seed cotton yield (33.71 q/ha) over rainfed condition (15.00 q/ ha). The growth attributes, yield contributing characters and ginning percentage were improved significantly in irrigation as compared to rainfed during both the seasons of experiment. The plant geometry of 120 cm × 45 cm recorded highest seed cotton yield (26.46 q/ha) and stood significantly superior over other planting geometries. It has 8.9 and 13.5% yield increment over 90 cm × 60 cm and 180 cm × 30 cm, respectively. All growth and yield contributing parameters were recorded significantly higher with 120 cm × 45 cm plant geometry as compared to other planting geometries, except plant height (cm), monopodials/plant, leaf area (dm2) and dry matter accumulation (g/plant). Application of nitrogen @ 150 kg N/ha to Bt cotton increases 25.5% and 8.6% seed cotton yield over 100 kg N/ha and 125 kg N/ha, respectively. Quality parameters did not influence significantly by irrigation, planting geometries and nitrogen levels confirms that fibre properties governs by genetic makeup and least affected by management practices.

Glufosinate Safety in WideStrike® Acala Cotton

WideStrike® Acala cotton is a two-gene, in-plant trait that provides broad-spectrum and season-long control of lepidopteran insect pests, and the varieties available in California also have resistance to glyphosate. There have been indications that WideStrike cotton has some glufosinate tolerance as well, so the level of tolerance to glufosinate needed to be ascertained. A 2-yr (2008 and 2009) study was conducted in California to evaluate the potential crop injury caused by three different rates (0.59, 0.88, and 1.76 kg ai ha−1) of glufosinate–ammonium at four different growth stages (cotyledon, 2-node, 5- to 6-node, and 18- to 19-node stages) of WideStrike Acala cotton. The effects of these treatments on the cotton plants and yield were closely monitored. Glyphosate at 1.54 kg ae ha−1 was applied at all cotton growth stages as a standard application, and a nontreated control was included. The greatest level of injury (58%) was observed with the highest rate of glufosinate applied at both the cotyledon and the two-node stage of cotton. However, injury was less than 10% following glufosinate at 0.59 kg ha−1 applied at the 18- to 19-node stage. The level of injury increased with the higher application rate of glufosinate at all crop growth stages. In 2008 and 2009, the glufosinate treatments had no effect on cotton lint yield. Therefore, the study showed that glufosinate can be applied safely topically at 0.59 kg ha−1 at the cotyledon- to 2-node stage or as POST-directed spray between the 5- to 19-node stages. Although injury occurred at this rate, the plants recovered within 2 to 3 wk of the treatment. Increasing glufosinate rates beyond 0.59 kg ha−1 can increase the possibility of greater crop injury.

Climatic Factors: Evaporation, Sunshine, Relative Humidity, Soil and Air Temperature and Cotton Production

This study investigated the effect of climatic factors (namely, evaporation, sunshine, relative humidity, soil temperature, and air temperature) on flower and boll production and retention in cotton (Gossypium barbadense). Also, this study investigated the relationship between climatic factors and production of flowers and bolls obtained during the development periods of the flowering and boll stage, and to determine the most representative period corresponding to the overall crop pattern. Evaporation, sunshine duration, relative humidity, surface soil temperature at 1800 h, and maximum air temperature, are the important climatic factors that significantly affect flower and boll production. The least important variables were found to be surface soil temperature at 0600 h and minimum temperature. There was a negative correlation between flower and boll production and either evaporation or sunshine duration, while that correlation with minimum relative humidity was positive. Higher minimum relative humidity, short period of sunshine duration, and low temperatures enhanced flower and boll formation. Temperature appeared to be less important in the reproduction growth stage of cotton in Egypt than evaporation (water stress), sunshine duration and minimum relative humidity. These findings concur with those of other researchers except for the importance of temperature. A possible reason for that contradiction is that the effects of evaporation rate and relative humidity were not taken into consideration in the research studies conducted by other researchers in other countries. Review Article Annual Research & Review in Biology, 4(18): 2835-2855, 2014 2836

Statistical Relation Nature between Climatic Variables and Soil Moisture during the Production of Cotton (Gossypium barbadense)

The information on impact of climatic factors on cotton production is not generally available, or at least not available or at least not available in the required form. Understanding this impact may help physiologists determine a possible control of the flowering mechanism in cotton plant. Field trials, in two successive seasons using cotton G. barbadense were carried out, to investigate the relationships between climatic factors, soil moisture status, and flower and boll production. The climatic factors considered were daily maximum air temperature, minimum air temperatures, maximum-minimum temperature (diurnal temperature range), sunshine duration, maximum relative humidity, minimum relative humidity, and wind speed. Minimum relative humidity and sunshine duration were the most significant climatic factors affecting flower and boll retention and production. Temperature appeared to be less important in the reproduction growth stage of cotton in Egypt than minimum relative humidity and sunshine duration. The soil moisture status showed low and insignificant correlation to flower and boll production [1].