Cotton Shoot Research Articles

Assessment of tolerance to glyphosate and glufosinate in genetically modified cotton shoots

Destruction of the harvest of cotton stalks should be done after it. However, destruction by ploughing prevents continuing with direct sowing, which makes chemical management an ally in soil conservation. The objective was to identify the most effective dose of 2,4-D, associated with different herbicides and the timing of administration for the control of transgenic cotton shoots for tolerance to glyphosate and glufosinate. The treatments consisted of the use of the herbicide 2,4-D, alone at doses of 670 and 1 340 g ha-1, and associated with the herbicides carfentrazone, flumiclorac, chlorimuron, flumioxazin and imazethapyr at three application times: 0 days after mechanical mowing (0 DAMM), 25 DAMM, and 0 DAMM + 25 DAMM. Regrowth evaluations were performed at 15, 30, and 45 days after the first and second applications, determining the dry biomass of the shoots. In terms of herbicide use time, the best results are obtained when they applied at 0 DAMM + 25 DAMM. Higher doses of 2,4-D (1 324 g ha-1) make it more efficient; in relation to herbicides, variations were perceived in their behavior depending on the time of evaluation, the application, and the dose of 2,4-D used. During the last measurement period, 45 days after application, 2,4-D+carfentrazone and 2,4-D+flumiclorac had the lowest dry shoot masses. The experiment was conducted in 2014. It was concluded that there is a lower rate of cotton regrowth when the application of the herbicides is repeated at 0 DAMM and 25 DAMM. The 1 324 g ha-1 dose of 2,4-D is more efficient. 2,4-D+carfentrazone and 2,4-D+flumiclorac promoted lower dry mass 45 days after administration of the treatments.

Effect of carboxymethyl cellulose and gibberellic acid-enriched biochar on osmotic stress tolerance in cotton

The deleterious impact of osmotic stress, induced by water deficit in arid and semi-arid regions, poses a formidable challenge to cotton production. To protect cotton farming in dry areas, it’s crucial to create strong plans to increase soil water and reduce stress on plants. The carboxymethyl cellulose (CMC), gibberellic acid (GA3) and biochar (BC) are individually found effective in mitigating osmotic stress. However, combine effect of CMC and GA3 with biochar on drought mitigation is still not studied in depth. The present study was carried out using a combination of GA3 and CMC with BC as amendments on cotton plants subjected to osmotic stress levels of 70 (70 OS) and 40 (40 OS). There were five treatment groups, namely: control (0% CMC-BC and 0% GA3-BC), 0.4%CMC-BC, 0.4%GA3-BC, 0.8%CMC-BC, and 0.8%GA3-BC. Each treatment was replicated five times with a completely randomized design (CRD). The results revealed that 0.8 GA3-BC led to increase in cotton shoot fresh weight (99.95%), shoot dry weight (95.70%), root fresh weight (73.13%), and root dry weight (95.74%) compared to the control group under osmotic stress. There was a significant enhancement in cotton chlorophyll a (23.77%), chlorophyll b (70.44%), and total chlorophyll (35.44%), the photosynthetic rate (90.77%), transpiration rate (174.44%), and internal CO2 concentration (57.99%) compared to the control group under the 40 OS stress. Thus 0.8GA3-BC can be potential amendment for reducing osmotic stress in cotton cultivation, enhancing agricultural resilience and productivity.

Optimizing brackish water and nitrogen application regimes for soil salinity, yield, fertilizer and water productivity of a mulched drip irrigated cotton cropping system

ContextBrackish water irrigation poses a threat to the sustainability of irrigated dryland crop systems, making it essential to identify effective water and nutrient management regimes to mitigate salt impact on agriculture. ObjectiveThis project is focused on determining the optimal combination of brackish irrigation water and nitrogen application in the mulched drip irrigation cultivation system for cotton crops in Xinjiang. MethodsThe combined effects of three brackish water irrigation amounts (I) (I1, 337 mm; I2, 412 mm; and I3, 562 mm) and three nitrogen application levels (N) (N1, 160 kg ha−1; N2, 315 kg ha−1; and N3, 395 kg ha−1) were investigated on soil salinity, cotton (Gossypium hirsutum L.) growth, nitrogen fertilizer and water productivity under mulched drip irrigation. The experiment was conducted over two growth cycles using a split-plot design with three replication treatments, with I arranged in the main plots and N in the subplots. ResultsResults indicated that irrigation amount, nitrogen application level, and their interaction significantly affected soil salt accumulation, cotton shoot biomass and yield, cotton nitrogen uptake (NU), nitrogen partial factor productivity (NPFP), and water productivity (WP). Additionally, the main effect year had a significant effect on all study variables, with higher values observed in 2017 compared to 2016, except for soil salt accumulation. The highest cotton shoot biomass, yield, NU, and WP as well as the lowest soil salt accumulation in mulched strips were both obtained in the I2N2 treatment. ConclusionThis treatment can be an optimal water and nitrogen management strategy for the cotton planting system under mulched drip irrigation and is crucial for achieving water and fertilizer savings in dryland conditions with brackish water irrigation.

Iron-modified biochar reduces nitrogen loss and improves nitrogen retention in Luvisols by adsorption and microbial regulation

Nitrogen (N) loss poses a great threat to global environmental sustainability. The application of modified biochar is a novel strategy to improve soil nitrogen retention and alleviate the negative effects caused by N fertilizers. Therefore, in this study iron modified biochar was used as a soil amendment to investigate the potential mechanisms of N retention in Luvisols. The experiment comprised five treatments i.e., CK (control), 0.5 % BC, 1 % BC, 0.5 % FBC and 1 % FBC. Our results showed that the intensity of functional groups and surface structure of FBC was improved. The 1 % FBC treatment showed a significant increment in soil NO3−-N, dissolved organic nitrogen (DON), and total nitrogen (TN) content by 374.7 %, 51.9 %, and 14.4 %, respectively, compared with CK. The accumulation of N in cotton shoots and roots was increased by 28.6 % and 6.6 % with 1 % FBC addition. The application of FBC also stimulated the activities of soil enzymes related to C and N cycling i.e., β-glucosidase (βG), β-Cellobiohydrolase (CBH), and Leucine aminopeptidase (LAP). In the soil treated with FBC, a significant improvement in the structure and functions of the soil bacterial community was found. FBC addition altered the taxa involved in the N cycle by affecting soil chemical properties, especially for Achromobacte, Gemmatimonas, and Cyanobacteriales. In addition to direct adsorption, the regulation of FBC on organisms related to N-cycling also played an important role in soil nitrogen retention.

Critical Period of Weed Control in Cotton (Gossypium hirsutum L.) at Three Nitrogen Levels*

The critical period for weed control is that part of the cropgrowth cycle during which the crop must be kept weed-free to preventunacceptable yield losses. Field studies were conducted for twoconsecutive years, 2004 and 2005, in the Thessaly plain in central Greeceto determine the critical period for weed control in cotton at three nitrogenlevels (50,100, and 150 kg N ha-1 ).Treatments of increasing duration ofweed interference and weed-free period were imposed at biweeklyintervals from 0 to 10 weeks after crop emergence (WAE). Based on anarbitrarily acceptable yield loss level of 5% and 10%, the beginning andend of the critical period were determined by fitting the polynomialregression to relative yield data representing increasing duration of weedinterference and weed-free period. Plant height, shoot and root dryweights and yield of cotton were reduced by prolonged delays in weedremoval at all nitrogen levels in 2004 and 2005. The results showed thatweeds reduced cotton shoot and root dry weights, respectively, by 55%and 38 % at 50 kg N ha-1 , 50% and 42 % at 100 kg N ha-1 and 40% and 46% at 150 kg N ha -1 , when allowed to compete for two weeks. At 10%acceptable yield loss level, the critical period was 8.2 weeks, starting 0.4WAE and ending 8.6 WAE at 50 kg N ha -1 , and was decreased to 7weeks, starting 1 WAE and ending 8 WAE at 100 kg N ha-1 . The criticalperiod decreased to 6.1 weeks, at 150 kg N ha -1 , starting 1.3 WAE andending 7.4 WAE. These findings showed that the supply of nitrogen to thecrop and weeds significantly influenced the crop-weed interferenceduration. This information will be useful for providing weed controlrecommendation to cotton producers.

GROWTH AND DEVELOPMENT OF COTTON CULTIVATED AFTER Urochloa spp.

No-tillage systems (NTSs) are generally known for their beneficial effects, whether on soil attributes or the yield of the target crop. For instance, research has explored the benefits of growing target crops, such as soybean or cotton, on soil previously occupied by a cover crop. However, fewer studies have investigated the potential negative implications of NTSs. Since, certain cover crops can release exudates harmful to other plants, there is a need to fill this knowledge gap. To this end, this study used four experiments to investigate the effects of two species of Urochloa on cotton germination, plant emergence, and biomass production. In the first two experiments, cotton germination was evaluated by placing seeds on paper rolls moistened with different concentrations of root washings of Urochloa plants cultivated for 45 days in tubes kept in a greenhouse, and desiccated with or without glyphosate. In the other two experiments, the emergence and biomass production of cotton were evaluated, which was sown in pots where two species of Urochloa were previously grown and subsequently desiccated or not with glyphosate, and managed in three ways: a) the entire plant of Urochloa spp. was kept in the pot (shoots and roots in the soil), b) only the aerial parts of Urochloa spp. were kept on the soil surface, and c) only the roots of Urochloa spp. were kept in the soil. Cotton seed germination was negatively affected by Urochloa spp. root washings. Both the emergence percentage and emergence speed index of the cotton plants were negatively affected when only the leaves of Urochloa spp. were kept in the soil with and without glyphosate desiccation. No adverse effect of the treatments (pre-cultivation and management of Urochloa spp.) on the production of cotton shoot and root biomass was observed.

Estimation of Cotton Nitrogen Content Based on Multi-Angle Hyperspectral Data and Machine Learning Models

For crop growth monitoring and agricultural management, it is important to use hyperspectral remote sensing techniques to estimate canopy nitrogen content in a timely and accurate manner. The traditional nadir method has limited ability to assess the nitrogen trophic state of cotton shoots, which is not conducive to high-precision nitrogen inversion, whereas the multi-angle remote sensing monitoring method can effectively extract the canopy’s physicochemical information. However, multi-angle spectral information is affected by a variety of factors, which frequently causes shifts in the band associated with nitrogen uptake, and lowers the estimation accuracy. The capacity of the spectral index to estimate aerial nitrogen concentration (ANC) in cotton was therefore investigated in this work under various observation zenith angles (VZAs), and the Relief−F method was employed to select the best spectral band with weight for ANC that is insensitive to VZA. Therefore, in this study, the ability of the spectral index to estimate ANC in cotton was explored under different VZAs, and the Relief-F algorithm was used to optimize the optimal spectral band with weight for ANC that is insensitive to VZA. The angle insensitive nitrogen index (AINI) for various VZAs was calculated using the expression (R530 − R704)/(R1412 + R704). The results show that the correlation between the spectral index and the ANC chosen in this study is stronger than the correlation between off-nadir observations, and the correlation coefficients between Photochemical Reflectance Index (PRI), AINI, and ANC are highest when VZA is −20° and −50° (r = 0.866 and 0.893, respectively). Compared with the traditional vegetation index, AINI had the best correlation with ANC under different VZAs (r > 0.84), and the performance of ANC in the backscatter direction was estimated to be better than that in the forward-scatter direction. At the same time, the ANC estimation model of the optimal indices AINI and PRI was combined with the machine learning method to achieve better accuracy, and the prediction accuracy of the random forest (RF) model was R2 = 0.98 and RMSE = 0.590. This study shows that the AINI index can estimate cotton ANC under different VZAs. Simultaneously, the backscattered direction is revealed to be more conducive to cotton ANC estimation. The findings encourage the use of multi-angle observations in crop nutrient estimation, which will also help to improve the use of ground-based and satellite sensors.

Dissolved organic matter-assisted phytoremediation potential of cotton for Cd-contaminated soil: a relationship between dosage and phytoremediation efficiency.

Dissolved organic matter (DOM) is a novel Cd-contaminated soils amendment for phytoremediation. However, the phytoremediation efficiency for different DOM doses has been insufficiently investigated. In this study, we investigated the effect of five DOM doses (v/w, 0%, 1%, 2%, 4% and 8%) on the phytoremediation efficiency of cotton in Cd-contaminated soil through pot experiment. The results showed that bioavailable Cd concentrations and organic matter in the soil increased with the increased of DOM dosage. The DOM dose increased the chlorophyll content, photosynthesis, and the total biomass of cotton. In addition, the DOM application increased the Cd content in cotton roots and changed the Cd uptake in cotton shoots, increasing shoot Cd extraction efficiency by 8.53-20%. Simultaneously, soil Cd phytoextraction efficiency significantly increased. Furthermore, applying a 1% DOM dose resulted in safeguarding fibre biomass and maximising the efficiency of shoot extraction. Redundancy analysis showed that the Mn content in leaves is critical for increasing cotton biomass, anti-oxidation competence and phytoremediation efficiency under 1% DOM dose. In conclusion, DOM enhanced cotton remediation in Cd-contaminated soils and applying DOM at 1% was a suitable choice for Cd-contaminated soils.

Cotton resistance to white mold (Sclerotinia sclerotiorum) evaluated by the oxalic acid method

The white mold (Sclerotinia sclerotiorum) is one of the most destructive cotton disease. Genetic resistance is one of the main strategies to control this disease. Thus, this study aimed to determine an appropriate period of exposition and concentration of oxalic acid to identify levels of physiological resistance to white mold in white fiber cotton genotypes. The study was implemented in two periods (August to October and November to January) in randomized complete block design, in a split-split-plot factorial in time, with five replications, where the plot factor was the concentration of oxalic acid (20; 40 mM) and the sub-plot factor was the 20 cotton genotypes, the sub-sub-plot factor was the time of exposure to oxalic acid (24h; 48h; 72h). The experimental units, or plots, were composed of test tubes with one cotton plant shoot partially immersed in oxalic acid solution. The biomass of the cotton shoots was evaluated at 24, 48, and 72 h. The loss of water caused by the exposure to oxalic acid indirectly indicates the level of cotton resistance to white mold. The results suggest that the most appropriate exposition time and concentration of oxalic acid for cotton evaluation of resistance to white mold were 20 mM at 48 hours, respectively. In these conditions, the cotton genotypes that presented the greatest average fresh mass were: UFU-14 A, UFU-14 B, UFU-14 F, UFU-14 H, and UFU-14 S, which could be used as sources of resistance to white mold in cotton breeding programs

Family-Wide Evaluation of Multiple C2 Domain and Transmembrane Region Protein in Gossypium hirsutum.

Multiple C2 domain and transmembrane region proteins (MCTPs) are a group of evolutionarily conserved proteins and show emerging roles in mediating protein trafficking and signaling transduction. Although, several studies showed that MCTPs play important roles during plant growth and development, their biological functions in cotton remain largely unknown. Here, we identify and characterize 33 GhMCTP genes from upland cotton (Gossypium hirsutum) and reveal the diverse expression patterns of GhMCTPs in various tissues. We also find that GhMCTP7, GhMCTP12, and GhMCTP17 are highly expressed in the main stem apex, suggesting their possible roles in shoot development. Through analyzing different cotton species, we discover plant heights are closely related to the expression levels of GhMCTP7, GhMCTP12, and GhMCTP17. Furthermore, we silence the expression of GhMCTP genes using virus-induced gene silencing (VIGS) system in cotton and find that GhMCTP7, GhMCTP12, and GhMCTP17 play an essential role in shoot meristem development. GhMCTPs interact with GhKNAT1 and GhKNAT2 and regulate meristem development through integrating multiple signal pathways. Taken together, our results demonstrate functional redundancy of GhMCTPs in cotton shoot meristem development and provide a valuable resource to further study various functions of GhMCTPs in plant growth and development.

Soil conditions affect cotton root distribution and cotton yield under mulched drip irrigation

Film-mulched drip irrigation with brackish water has been used widely for cotton (Gossypium hirsutum L.) production in arid regions. Full consideration of the promise of brackish water irrigation requires consideration of the dependence of cotton root characteristics on soil conditions. To date, these dependences are complex and poorly understood. The present study compared the impacts of soil temperature, water and salinity on root characteristics on cotton yield for brackish water irrigation treatment (BWT) and fresh water irrigation treatment (FWT). Spatial differences were observed for cotton root mass, root length, root surface-area and root volume distribution that corresponded with differences in the distributions of soil conditions. There existed a strikingly linear relationship between cotton root length and root mass. Soil temperature did not exert clear control on root system growth. Lower average root density and coarser roots were observed for BWT than for FWT as a result of the reduced soil temperature and the elevated soil salinity associated with BWT. Cotton shoot growth was more sensitive than root growth to salt stress for BWT. Higher root density and fine root proportion for FWT than BWT led to higher cotton yield. That is, more cotton roots were observed in the shallow mulched zone, which corresponded with high root water uptake rate and salt accumulation. Our study indicated that the easily-measured cotton root mass could be used as a practical surrogate for root length under mulched drip irrigation. Subsurface drip irrigation with drip tapes set in the shallow mulched zone may further promote cotton root system growth, allowing for sustainable cotton production with brackish water irrigation.

Qualitative parameters and nutritional potential of arboreal cotton silage

Abstract: The objective of this work was to evaluate the qualitative parameters and nutritional potential of silage of arboreal cotton (Gossypium hirsutum) shoots. The experiment was carried out in a 4×2 factorial arrangement, for two silage forms (in natura or pre-dried), with four treatments, as follows: without additives (WA); with inoculant (WI); with 2% ground corn (GC); and with 2% ground corn with inoculant (GC+I). The fermentative quality and nutritional parameters of the silages were evaluated. Fermentative quality was better in the WI and GC+I silages. The dry matter content was higher in the pre-dried silage, while the crude protein contents of in natura silage were higher in the WA and WI treatments. The lowest values of neutral detergent fiber and acid-digested lignin were observed in the WI treatment, for pre-dried silage. Total digestible nutrients and total volume of gas were higher in the pre-dried silage, in the WI and GC treatments, respectively. In vitro dry matter digestibility was lower in WA silage, in both forms. Silage of arboreal cotton associated with inoculant or with inoculant with ground corn shows a better fermentation profile and improves the energy and nutritional values, both in natura and pre-dried forms; however, in natura silage is less laborious for rural producers.

An isopentyl transferase gene driven by the senescence-inducible SAG12 promoter improves salinity stress tolerance in cotton

BackgroundSoil salinity seriously affects cotton growth, leading to the reduction of yield and fiber quality. Recently, genetic engineering has become an efficient tool to increase abiotic stress tolerance in crops.ResultsIn this study, isopentyl transferase (IPT), a key enzyme involved in cytokinin (CTK) biosynthesis from Agrobacterium tumefaciens, was selected to generate transgenic cotton via Agrobacterium-mediated transformation. A senescence-inducible SAG12 promoter from Arabidopsis was fused with the IPT gene. Ectopic-expression of SAG12::IPT significantly promoted seed germination or seedling tolerance to salt stress. Two IPT transgenic lines, OE3 as a tolerant line during seed germination, and OE8 as a tolerant line at seedling stage, were selected for further physiological analysis. The data showed that ectopic-expression of SAG12::IPT induced the accumulation of CTKs not only in leaves and roots, but also in germinating seeds. Moreover, ectopic-expressing IPT increased the activity of antioxidant enzymes, which was associated with the less reactive oxygen species (ROS) accumulation compared with control plants. Also, ectopic-expression of IPT produced higher K+/Na+ ratio in cotton shoot and root.ConclusionThe senescence-induced CTK accumulation in cotton seeds and seedlings positively regulates salt stress partially by elevating ROS scavenging capability.

The Cotton High-Affinity K+ Transporter, GhHAK5a, Is Essential for Shoot Regulation of K+ Uptake in Root under Potassium Deficiency.

Potassium (K) deficiency is a key limiting factor in cotton (Gossypium hirsutum) production. By grafting two contrasting cotton cultivars, CCRI41 (more susceptible to K+ deficiency) and SCRC22 (more tolerant of K+ deficiency), we established that cotton shoot plays a vital role in the regulation of root K+ uptake. To identify the genetic basis of this finding, we performed RNA sequencing (RNA-seq) of roots of CCRI41 self-grafts (CCRI41/CCRI41, scion/rootstock) and SCRC22/CCRI41 reciprocal-grafts exposed to K+ deficiency. We found that GhHAK5a, an orthologous of Arabidopsis thaliana high-affinity K+ transporter, AtHAK5, was significantly induced in the CCRI41 rootstock by the SCRC22 scion. This gene was mainly expressed in roots and was more highly induced by K+ deficiency in roots of SCRC22 than those of CCRI41. Agrobacterium-mediated virus-induced gene silencing and yeast complementary assay showed that GhHAK5a is a high-affinity K+ uptake transporter. Importantly, silencing of GhHAK5a in the CCRI41 rootstock almost completely inhibited the K+ uptake induced by SCRC22 scion in CCRI41 rootstock. We identified a key high-affinity K+ transporter, GhHAK5a in cotton, which is the essential target for shoot regulation of root K+ uptake under K+ deficiency.

Natural variation in a CENTRORADIALIS homolog contributed to cluster fruiting and early maturity in cotton

BackgroundPlant architecture and the vegetative-reproductive transition have major impacts on the agronomic success of crop plants, but genetic mechanisms underlying these traits in cotton (Gossypium spp.) have not been identified.ResultsWe identify four natural mutations in GoCEN-Dt associated with cluster fruiting (cl) and early maturity. The situ hybridization shows that GhCEN is preferentially expressed in cotton shoot apical meristems (SAM) of the main stem and axillary buds. Constitutive GhCEN-Dt overexpression suppresses the transition of the cotton vegetative apex to a reproductive shoot. Silencing GoCEN leads to early flowering and determinate growth, and in tetraploids causes the main stem to terminate in a floral bud, a novel phenotype that exemplifies co-adaptation of polyploid subgenomes and suggests new research and/or crop improvement approaches. Natural cl variations are enriched in cottons adapted to high latitudes with short frost-free periods, indicating that mutants of GoCEN have been strongly selected for early maturity.ConclusionWe show that the cotton gene GoCEN-Dt, a homolog of Antirrhinum CENTRORADIALIS, is responsible for determinate growth habit and cluster fruiting. Insight into the genetic control of branch and flower differentiation offers new approaches to develop early maturing cultivars of cotton and other crops with plant architecture appropriate for mechanical harvesting.

Трофічні зв'язки бавовникової совки за сучасних технологій вирощування соняшнику та кукурудзи в Лісостепу України

The features of reproduction of cotton shoots of sunflower seeds and corn under modern agricultural systems in the forest-steppe of Ukraine are highlighted. The analysis of efficiency of application of modern monitoring of a complex of pests at new systems of protection of sunflower and corn is carried out. On the crops of sunflower and corn in the Poltava region, Mirgorod district, the dynamics of the number of cotton bollworm, in the period 2014-2018, which reflects a sharp fluctuation in the number of pests in the crops, is reflected. The basic ecological and biological peculiarities of formation of the structure of cotton bollworm in the crops of the studied cultures are determined. The feature of monitoring and control of cutworms in the forest-steppe of Ukraine is highlighted. A complex of the most effective biological insecticides is described, for controlling the amount of the pest. The analysis of efficiency of modeling of the number of harmful and useful insect species for resource-saving systems of protection of sunflower and corn is carried out. The peculiarities of biology and ecology, as well as the phenology of the development of cotton bollworm in the research area have been specified. The peculiarities of forming the number of pests in agrocenosis vary according to certain parameters, optimum temperatures during winter hibernation, warm and moderate-humid weather in the spring-summer period of vegetation and the presence of honey plants during the period of the imago. For effective crop management, it is relevant to determine the total demand of pests in feeding on the actual population of individuals at different stages of ontogenesis of cereals and industrial crops. Also, a comprehensive set of preventive measures for the distribution of cotton shoots in sunflower and corn crops, for modern agricultural systems. Application in the production of methods for forecasting the dynamics of phytophagous crops on cereals and industrial crops due to the influence of biotic and abiotic factors in different periods of development of plants and phytophagous, allows to determine quantitative changes of cotton bollworms in time and space. Keywords: trophic relations, cotton bollworm, sunflower, maize, monitoring

Rapid and convenient transformation of cotton (Gossypium hirsutum L.) using in planta shoot apex via glyphosate selection

Cotton plants are recalcitrant with regards to transformation and induced regeneration. In the present study, 5-enolpyruvylshikimate-3-phosphate (EPSPS), a glyphosate resistant gene from the bacterium Agrobacterium sp. strain CP4, was introduced into an elite Bt transgenic cotton cultivar with a modified technique involving in planta Agrobacterium-mediated transformation of shoot apex. Primary transformants were initially screened using a 0.26% glyphosate spray and subsequently by PCR analysis. Five out of 4 000 transformants from T1 seeds were obtained resulting in an in planta transformation rate of 0.125%. Four homozygous lines were produced by continuous self-fertilization and both PCR-based selection and glyphosate resistance. Transgene insertion was analyzed by Southern blot analysis. Gene transcription and protein expression levels in the transgenic cotton lines were further investigated by RT-PCR, Western blot, and ELISA methods. Transgenic T3 plants were resistant to as much as 0.4% of glyphosate treatments in field trials. Our results indicate that the cotton shoot apex transformation technique which is both tissue-culture and genotype-independent would enable the exploitation of transgene technology in different cotton cultivars. Since this method does not require sterile conditions, the use of specialized growth media or the application of plant hormones, it can be conducted under the greenhouse condition.

Seletividade do herbicida fomesafen isolado ou em associação com diuron, trifluralin e prometryn para cultivares de algodoeiro

The objective of this work was to evaluate the selectivity of fomesafen, in single application or in association with other herbicides, in pre-emergence of six cotton cultivars. Six experiments were conducted simultaneously in greenhouse conditions, in Red Oxisoil in water with pH of 5,9; 2,94% of OM and 320g kg-1 of clay. The experimental design was completely randomized with five replicates. Treatments were arranged in a factorial scheme (2 x 4) + 1, represented by two doses of fomesafen (375 and 500 g ha-1 - active ingredient) and association with diuron (1,25 kg ha-1 a.i.), trifluralin (1,80 kg ha-1 a.i.) and prometryn (1,25 kg ha-1 a.i.). A herbicide-free treatment was also added. At 30 days after the application of treatments, the cotton shoot was collected to quantify the dry mass accumulation. It was observed that the single fomesafen application or its association with diuron, trifluralin and prometryn affected the dry mass accumulation of the six cultivars. In general, the association of fomesafen with trifluralin was the most selective treatment. There is a differential response of cotton cultivars to fomesafen. The cultivar IMA CD 6001 LL was the most tolerant and IMA 8221 was the most sensible to fomesafen and its associations.

Morpho-physiological Responses of Cotton Shoot Apex to the Chemical Top-ping with Fortified Mepiquat Chloride

Morpho-physiological Responses of Cotton Shoot Apex to the Chemical Top-ping with Fortified Mepiquat Chloride

Mechanical properties of cotton shoots for topping

Cutting the shoots of cotton plants (topping) at about 10–20 cm from the top of plants is a cultural practice, which may offer advantages to improve yield and yield components in cotton production. The cutting forces of plant stalks were reported in the literature, which help understand the mechanical properties of stalks for a cultivar of field crops. However, the shearing characteristics of cotton shoots have not been addressed yet. The objective of this study was to determine some physical and mechanical properties of cotton (Gossypium hirsutum L.) shoots. The test specimens were obtained from two different plant segments, i.e. 0–15 cm (Segment A) and 16–30 cm (Segment B) from the top of cotton plants, in 21 plots in an ongoing cotton topping study. The samples were collected from each plot and were subjected to shearing test using a universal test machine in the laboratory. In Segment A, average shoot diameter, shearing force, water content, maximum shearing stress, and specific shearing energy were determined to be 4.35 mm, 73 N, 72%, 4.94 MPa, and 0.069 J mm−2, respectively. In Segment B the same parameters were 5.79 mm, 121 N, 64.8%, 4.65 MPa, and 0.078 J mm−2, respectively. The difference between the Segment A and B was significant at 5% level for shearing stress while all others parameters showed differences at 1% level. Although displacement at the bioyield point was similar in both sampling locations, the maximum shearing force requirement was more (121 N) in Segment B compared with Segment A (73 N) suggesting that topping should be done as high as possible from the ground to complete the topping process with low energy consumption. In terms of cutting energy requirement, it was concluded that the topping should be done as early as possible from 100 to 120 days from the planting.