Boll Formation Research Articles

English

The effects of reducing N fertilizer use on soil NO3--N content and cotton yield were studied through a three-year (2015 to 2017) field experiment in South Xinjiang of China. Cotton was sown under drip irrigation system using five N fertilizer reduction treatments as: conventional N application rate (N100), N application rate reduced by 16.67% (N-16.67), 33.33% (N-33.33), 50% (N-50), and 100% (N-100). The data were recorded for changes in soil NO3--N content, and the SPAD value of cotton leaves was recorded at the peak bolling stage. The total N content of the plant was recorded at the boll formation stage, while yield was recorded at maturity. The results revealed that the soil NO3--N content in N-16.67, N-33.33, N-50, and N-100 treatments decreased by 10.8, 45.5, 60.7 and 72.3% compared to N100 treatment, respectively. The SPAD values of N-16.67 and N-33.33 treatments were significantly higher than those of N100 treatment, while the SPAD values of N-50 and N-100 treatments were significantly decreased. The total N content of cotton was significantly decreased with the increase in the proportion of N fertilizer reduced. The seed cotton yield in N-16.67 and N-33.33 treatments increased by 9.2 and 7.9% compared to the N100 treatment, respectively. However, the cotton yield decreased significantly when the N application rate was reduced by 50 and 100%. The relationship between the N fertilizer reduction rate and cotton yield suggested that the N application rate can be reduced by 18.47–45.50% without compromising the cotton yield in South Xinjiang of China. © 2021 Friends Science Publishers

Cotton irrigation scheduling improvements using wetting front detectors in Uzbekistan

Previous research established growth-stage-specific irrigation scheduling for upland cotton (Gossypium hirsutum L.) in Uzbekistan. We report further investigation of irrigation scheduling for two cotton varieties and its effect on seed-lint yield and irrigation crop water productivity with and without use of a wetting front detector (WFD) to trigger irrigation cessation. A WFD is a device buried in the soil to sense when the wetting front from irrigation reaches a certain depth. The depth may be adjusted upon installation of the WFD. Field trials were conducted in silt loam soil near Tashkent, Uzbekistan, in 2016, 2017, and 2018. The growth stages of germination to flowering, flowering to boll formation, and maturation were considered for the development of irrigation scheduling regimes with respect to field capacity water content (Fc). The best growth, development and seed-lint yield for the Sultan cotton variety were achieved with irrigations scheduled at soil water content levels of 70%, 75%, and 65% of Fc during the aforementioned three growth stages, respectively, and were achieved for variety UzPITI-103 with irrigations scheduled at 70%, 70%, and 60% of Fc during the aforementioned plant growth stages, respectively. There were appreciable varietal differences in water requirement with the early maturing Sultan variety having a larger water requirement. In contrast, irrigation scheduling with larger Fc values did not result in increasing the yield for the UzPITI-103 cotton variety. In comparison with irrigation without WFD, the use of the WFD decreased irrigation duration by 2.0–3.5 h, net irrigation amount by 7–90 m3ha−1, irrigation run off by 69–134 m3ha−1, and deep percolation below the root zone by 10–17 m3ha−1, while increasing irrigation crop water productivity by 0.08–0.10 kg m−3 and seed-lint yield by 0.04–0.10 Mgha−1. Irrigation scheduling regimes based on percentages of Fc and irrigation with WFD should be considered applicable practices for upland cotton varieties on silt loam soils of the central zone of Uzbekistan and for similar soil-climatic conditions of Central Asian countries.

Response of some physiological components of cotton to surface and subsurface drip irrigation using different irrigation water levels

This study was carried out to determine the leaf water potential (LWP), stomatal conductance (SC) and leaf area index (LAI) of cotton crop using subsurface drip irrigation (SSDI) and surface drip irrigation (SDI) and different irrigation water levels based on the FAO-56 Penman-Monteith (PM) during the 2016 and 2017 growing seasons. The critical LWPs in vegetative period, flowering stage and boll formation stage in SDI for irigation time were -24, -23 and -24 bar, respectively. Considering the same putting in order for the crop development stages in SSDI-40 cm, those were -23, -23 and -24 bar, respectively. The values of LWP in SSDI-30 cm were the same levels in SSD-40 cm. LWP in the boll formation stage were, in general, lower (bigger in minus numerical number) compared to the first two development stages of the crop. The critical SCs in vegetative period, flowering stage and boll formation stage in SDI were 312.8, 201.8 and 198.9 mmol m-2 s-1, respectively. The values of SC in the same putting in order for the crop development stages in SSDI-30 cm and SSDI-40 cm were 368.8, 182.6 and 221.8 mmol m-2 s-1; and 371.7, 185.9 and 186.8 mmol m-2 s-1, respectively. SC decreased from the vegetative period through generative period of the crop. The SCs increased together with increasing amount of irrigation water and it decreased with increasing water stress conditions. The LAIs were 2.99, 3.11 and 3.45 in SDI, SSDI-30 cm and SSDI-40 cm, respectively. The values of LAI increased from the surface drip irrigation and lower irrigation water level applied through subsurface drip irrigation and highest level of amount of irrigation water. Although some plant physiological indicators such as LWP and SC might be used for irrigation scheduling and irrigation time, these indicators are highly affected by soil water status, temperature, light, air humidity and calibration of the devices used.

Soil applied boron (B) improves growth, yield and fiberquality traits of cotton grown on calcareous saline soil.

Boron (B) is required during all growth stages of cotton crop, especially during boll formation. However, Typic Haplocambid soils of cotton growing belt in Pakistan are B-deficient, which results in low yield and economic returns. Foliar application of B improves cotton productivity; however, information is limited on the role of soil applied B in improving cotton growth and yield. The current study investigated the role of soil applied B in improving growth, yield and fiber quality of cotton crop. Five different B doses (i.e., 0.00, 2.60, 5.52, 7.78 and 10.04 mg kg-1 of soil) and two cotton cultivars (i.e., CIM-600 and CIM-616) were included in the study. Soil applied B (2.60 mg kg-1) significantly improved growth, yield, physiological parameters and fiber quality, while 10.04 mg kg-1 application improved B distribution in roots, seeds, leaves and stalks. Significant improvement was noted in plant height (12%), leaf area (3%), number of bolls (48%), boll size (59%), boll weight (52%), seed cotton yield (52%), photosynthesis (50%), transpiration rate (10%), stomatal conductance (37%) and water use efficiency (44%) of CIM-600 with 2.60 mg kg-1 compared to control treatment of CIM-616. Similarly, B accumulation in roots, seeds, leaves and stalk of CIM-600 was improved by 76, 41, 86 and 70%, respectively compared to control treatment. The application of 2.60 mg kg-1 significantly improved ginning out turn (6%), staple length (3.5%), fiber fineness (17%) and fiber strength (5%) than no B application. The results indicated that cultivar CIM-600 had higher ginning out turn (1.5%), staple length (5.4%), fiber fineness (15.5%) and fiber strength (1.8%) than CIM-616. In crux, 2.60 mg kg-1 soil B application improved growth, yield, physiological and fiber quality traits of cotton cultivar CIM-600. Therefore, cultivar CIM-600 and 2.60 mg kg-1 soil B application is recommended for higher yield and productivity.

Effect of Spraying date of boron on Vegetative Growth and Yield of Cotton Plant (Gossypium hirsutum L.) Lashata Variety

A field experiment was conducted during the spring season of the year 2018 in the fields of the Cotton Research Unit at the Technical Agricultural College / Mosul to study the effect of spraying the element boron for different dates (the stage of vegetative growth, the stage of opening blooming buds, the stage of boll formation) and the interferences between these dates on the characteristics of vegetative growth and cotton components Lashata cultivar, and used the design of complete randomized block in the implementation of the experiment. The results of the study showed that the date of spraying with boron in the two stages of vegetative growth and flowering buds open significantly exceeds the rest of the dates in the characteristics of plant height (cm) and the number of nodes up to the first fruit branch and the number of vegetable branches and the number of fruit branches in values (135.8 cm, 6.1, 4.5, 16.8) respectively, the duration of spraying with boron in the vegetative stage exceeded the rest of the dates by its effect on the characteristics of the total number of bolls and the weight of one boll (gm), the seed index and the yield of the cast cotton values (36.8, 6.82 g, 4.050, 995.2 kg −1), respectively. the date of spraying is also superior in the vegetative stage of growth significantly on the rest of the dates on the characteristics of its effects type (E and percentage of hair and the percentage of the early) values (42.8, 40.5% staple guide, and 82.15%) respectively.

Foliar application of magnesium oxide nanoparticles on nutrient element concentrations, growth, physiological, and yield parameters of cotton

In order to investigate the effects of different magnesium (Mg) sources of fertilizers like magnesium sulfate (MgSO4), magnesium oxide (MgO), and magnesium oxide nanoparticles (nMgO) on cotton growth and development, a pot culture experiment was carried out at different concentrations viz., 20, 40, 60, 80, and 100 ppm in factorial completely randomized design (FCRD). From the pot culture studies, 60 ppm of nMgO was found as the optimal dose for improvement in SPAD chlorophyll value, boll weight, and seed cotton yield. Consequently, field experiment was carried out in randomized block design (RBD) with optimized dose of 60 ppm (from pot culture study) of Mg fertilizers like MgSO4, MgO, and nMgO to elucidate their effect on growth, physiological, yield, fiber quality parameters, and nutrient element concentrations in cotton. The treatments were foliar sprayed at vegetative and boll formation stages of cotton similar to pot culture studies. It is confirmed that foliar application of 60 ppm of 50 nm of MgO nanoparticles significantly increased the number of opened bolls per plant (20.6), single plant yield (58 g/plant) and seed cotton yield (1729 kg/ha). The increased seed cotton yield of 42.2, 39.9, and 24.8% was recorded by nMgO, MgO, and MgSO4 over control. Besides, fiber quality parameters like fiber length and fiber strength of cotton were improved by MgO nanoparticles than sulfate form of Mg fertilizers. Moreover, significant and positive influence was achieved by foliar nutrition of MgO nanoparticles on macronutrients like nitrogen (N), phosphorus (P), potassium (K), and Mg concentration in cotton plants.

Site-specific fertilizer nitrogen management in Bt cotton using chlorophyll meter

AbstractField experiments were conducted to standardize protocols for site-specific fertilizer nitrogen (N) management in Bt cotton using Soil Plant Analysis Development (SPAD) chlorophyll meter. Performance of different SPAD-based site-specific N management scenarios was evaluated vis-à-vis blanket fertilizer N recommendation. The N treatments comprised a no-N (control), four fixed-time and fixed N doses (60, 90, 120, and 150 kg N ha-1) including the recommended dose (150 kg ha-1), and eight fixed-time and adjustable N doses based on critical SPAD readings of 45 and 41 at first flowering and boll formation stages, respectively. The results revealed that by applying 45 or 60 kg N ha-1 at thinning stage of the crop and critical SPAD value-guided dose of 45 or 30 kg N ha-1 at first flowering stage resulted in yields similar to that recorded by applying the recommended dose of 150 kg N ha-1. However, significantly higher N use efficiency as well as 30–40% less total fertilizer N use was recorded with site-specific N management. Applying 30 kg N ha-1 at thinning and SPAD meter-guided 45 kg N ha-1 at first flowering were not enough and required additional SPAD meter-guided 45 kg N ha-1 at boll formation for sustaining yield levels equivalent to those observed by following blanket recommendation but resulted in 20% less fertilizer N application. Our data revealed that SPAD meter-based site-specific N management in Bt cotton results in optimum yield with dynamic adjustment of fertilizer N doses at first flowering and boll formation stages. The total amount of N fertilizer following site-specific management strategies was substantially less than the blanket recommendation of 150 kg N ha-1, but the extent may vary in different fields.

EFFECT OF DIFFERENT BORON APPLICATION ON COTTON YIELD COMPONENTS AND FIBER QUALITY PROPERTIES

This study was carried out to determine the effect of different boron application methods on cotton yield, plant growth and fiber technological properties. The study was conducted at Siirt University Faculty of Agriculture Department of Field Crops experimental area as randomized complete block design with four replications in 2018. Stoneville 468 cotton variety and boron liquid foliar fertilizer were used as material. Seven different boron applications were performed as (Control, 1000 cc ha-1 at pre-flowering stage, 2000 cc ha-1 at pre-flowering stage, 1000 cc ha-1 at flowering stage, 2000 cc ha-1 at flowering stage and 1000 cc ha-1 at boll formation stage, 2000 cc ha-1 at boll formation stage). The results of statistical analysis showed that there were significant differences between applications methods in terms of plant height and number of monopodial branches. But there were non-significant differences in terms of number of sympodial branches, number of first node of sympodial branch, number of nodes, height/node ratio, number of bolls, boll weight, seed cotton weight of per boll, number of seeds per boll, first picking percentage, 100 seeds weight, ginning percentage, seed cotton yield and fiber technological characteristics. In conclusion different application methods of boron increased plant height and number of monopodial branches of cotton when applied as 1000 and 2000 cc ha-1 at pre-flowering stages.

Role of mineral nutrition in alleviation of heat stress in cotton plants grown in glasshouse and field conditions

Coincidence of high temperature with terminal reproductive pheno-stages of cotton is chief constraint to achieve yield potential. This high temperature interfere plant defensive system, physiological process, water relations and lint yield production. In this study, we modulated the detrimental outcomes of heat stress on cotton through the foliar spray of nutrients. Cotton crop was exposed to sub-optimal and supra-optimal thermal regimes for a period of one week at squaring, flowering and boll formation stages under glass house and field conditions. Foliar spray of potassium (K-1.5%), zinc (Zn-0.2%) and boron (B-0.1%) were applied at three reproductive stages one day prior to expose high temperature regimes. High temperature increased lipid membrane damage through increased malondialdehyde (MDA) contents in cotton leaves. High temperature stress also reduced leaf chlorophyll contents, net photosynthetic rate, stomatal conductance, water potential, averaged boll weight (g) and seed cotton yield per plant. Various nutrients variably influenced growth and physiology of heat-stressed cotton plants. Zinc outclassed all other nutrients in increasing leaf SOD, CAT, POX, AsA, TPC activity, chlorophyll contents, net photosynthetic rate, stomatal conductance, water potential, boll weight and seed cotton yield per plant. For example, zinc improved seed cotton yield under supra-optimal thermal regime by 17% and under sub-optimal thermal regime by 12% of glasshouse study while 19% under high temperature sowing dates of field study than the water treated plants under the same temperatures. Conclusively, increasing intensities of temperature adversely affected the recorded responses of cotton and exogenous application of Zn efficaciously alleviated heat induced perturbations. Moreover, exogenous nutrients mediated upregulations in physiochemical attributes induced heat tolerance at morphological level.

Integrated Effects of Mulching Treatment and Nitrogen Fertilization on Cotton Performance under Dryland Agriculture

ABSTRACTCrop production in arid regions is characterized with high temperature, drought and salinity which decrease water and nutrient use efficiency. This study was conducted to investigate the effect of wheat residue mulch in relation to N fertilizer application rates for cotton productivity under dryland condition of Uzbekistan. Main plots were control of no mulch addition and a 5 t ha−1 mulch treatment. These plots were split into 5 N rate plots of 0, 70, 140, 210 or 280 kg of N ha−1. The results showed that mulching pattern decreased soil temperature by 0.7–1.5°C as compared to conventional treatment (CT), regardless of N fertilization rates. The soil water storage increased by 41.8, 17.3, 48.0 mm in the flowering, boll formation and ripening stages of cotton, respectively under mulching treatment. Soil available N concentration and nutrients uptake by plants consistently increased with the increase of N fertilization rates with positive correlations. At flowering period, the plant height, chlorophyll content, stem diameter, and a number of fruit branches in plants were higher by 32.3%, 46.8%, 26.7% and 55.3%, respectively at 210 kg N ha−1 under mulching treatment as compared to the non-fertilized control. The highest cotton yield was obtained at 210 kg N ha−1 application under mulching treatment. The correlation difference between mulch and N application rates was higher (R2 = 0.97) than the difference in CTs and N application rates (R2 = 0.89). This study showed that mulching had a greater impact to preserve nutrients and water resources in the soil, thereby improved cotton growth and yield.

Genetic effects conferring heat tolerance in upland cotton (Gossypium hirsutum L.)

BackgroundClimate change and particularly global warming has emerged as an alarming threat to the crop productivity of field crops and exerted drastic effects on the cropping patterns. Production of cotton has been dropped down to one million bales from 1.4 million bales since 2015 in Pakistan due to the increase in temperature at critical growth stages, i.e., flowering and boll formation. Keeping in view the importance of cotton in the country, this study was conducted to investigate the genetic effects conferring heat tolerance in six populations (P1, P2, F1, F2, BC1 and BC2) developed from cross-1 and cross-2, i.e., VH-282 × FH-142 and DNH-40 × VH-259.ResultsThe results revealed that cross-1 performed better in heat stress as compared with cross-2 for majority of the traits recorded. Boll weight and ginning outturn (GOT) were highly effected under heat stress and had negative correlation with Relative cell injury (RCI). Boll weight, fiber length, fiber strength and fiber fineness were under the control of non-additive gene action, whereas RCI was controlled by additive gene effects. Lower values of genetic advance coupled with higher values of broad sense heritability for these traits except RCI confirmed the role of non-additive genetic effects. Duplicate types of epistasis were recorded for fiber strength in cross-1 in normal condition. However, complementary type of non-allelic interaction was recorded for fiber strength under normal condition, fiber fineness and RCI under heat stressed condition in cross-1. Likewise, boll weight, GOT and fiber length in populations derived from cross-2 in normal condition were also under the influence of complementary type of non-allelic interaction. Significant differences among values of mid parent and better parent heterosis for boll weight in both normal and heat stress condition provided the opportunity to cotton breeders for utilization of this germplasm for improvement of this trait through exploitation of heterosis breeding.ConclusionCross-1 performed better in heat stress and could be utilized for development of heat tolerant cultivar. RCI was under the influence of additive gene action, so one can rely on this trait for screening of large number of accessions of cotton for heat stress. While other traits were predominantly controlled by non-additive gene action and selection based on these should be delayed in later generations.

English

Aiming to evaluate the gas exchange of upland cotton cultivars cultivated in the Brazilian semiarid, subject to water deficit periods on the phenological stages, an experiment was carried out at the Campina Grande Federal University, Pombal county campus, Paraíba State, Brazil, between June and December 2015. Treatments were formed from a split-plot arrangement, in which the plots were 6 water deficit periods (P) (P1 = No deficit, P2 = Deficit in the initial growth stage, P3 = Deficit in the flower bud stage, P4 = Deficit in the flower stage, P5 = Deficit in the boll stage and P6 = Deficit in the open boll stage) and the subplots, 2 upland cotton cultivars (C) (C1 = Brazil Seeds 286 and C2 = BRS 336), in randomized block design, with 4 replicates. Water deficits reduced the gas exchange of the upland cotton plants, mainly stomatal conductance, transpiration and photosynthesis. The cotton cultivars BRS 286 and BRS 336 presented similar behavior in the different water deficits applied on different phenological stages. Cotton was less tolerant to water deficits in the boll formation stage and more tolerant in the initial growth and flower bud stages. Key words: Gossypium hirsutum L. r. latifolium H., water stress, physiology. &nbsp

Planting Date Effects on Cotton Lint Yield and Fiber Quality in the U.S. Southern High Plains

Cotton planting date effects in the U.S. Southern High Plains (SHP) were evaluated based on 11 years of May-planted and June-planted irrigated variety trials. Multiple cultivars planted in each year’s trial allowed for the calculation of 153 yield effects and 162 effects in 5 fiber quality parameters. Yield and quality effects were considered in the context of related changes in total growing season degree days (GDDS) and total cool hours (CHRS) during a boll formation period 80 to 110 days after planting. May planting increased GDDS and significantly increased yields in 8 of 10 years that comparisons could be made. Micronaire and fiber elongation were the most sensitive quality parameters to planting date. June planting resulted in increased CHRS every year and a significantly higher incidence of low micronaire in 7 of 11 years. In 7 of 11 years May planting significantly reduced fiber elongation relative to June planting. Analysis of SHP temperature data show that late-April to early-May planting dates may increase yield and micronaire by maximizing GDDS and minimizing CHRS. Although this practice may be optimal to the SHP environment it may also require high-vigor seed and pre-planting irrigation. Adapting genetics to an early planting strategy might include selecting for improved seed vigor and cold germination with acceptable yield and fiber quality traits.

The Effect of Biofertilizers on Cotton (Gossypium hirsutum L.) Development Yield and Fiber Technological Properties

The aim of this study was to determine the effect of biofertilizer application on cotton yield, cotton growth and fiber technological properties. This study was carried out at faculty of agriculture, department of field crops, Siirt University, Turkey during 2017 cotton growing season. The experiment was conducted in randomized complete block design with four replications. Stoneville 468 cotton cultivar was used as plant material. In this experiment Coton Plus and Mega Flu have been used as biofertilizers to increase cotton yield and technological properties as opposed to the utilization of chemical fertilizer. Further, Cotton Plus is mixed microbial fertilizer which contains Bacillus subtilis, Paenibacillus azotofixans while Mega Flu contains three different genera of bacteria Bacillus megaterium, Pantoea agglomerans and Pseudomonas fluorences. The results of study indicated that there were significant differences between biofertilizers applications in terms of seed cotton yield, lint yield, ginning percentage, the number of monopodial branches, but there were non-significant differences observed in terms of lint quality characteristics except fiber elongation. The best results obtained from the application of biofertilizers at seed + square +flowering +boll formation periods. Comparing with control 1350 kg ha-1 higher yield was obtained from Coton-Plus application. Significant seed cotton yield and lint yield obtained by using few times biofertilizers at different growing stages (seed +squaring + flowering +boll forming stages). These findings indicated that yield increasing can be achieved by using biofertilizers few times instead of one time.

Establishing indicator leaf and its threshold values for need based nitrogen management using chlorophyll meter and leaf color chart in Bt cotton

Over application of fertilizer N to cotton is not only a potential threat to environment but also leads to increased costs of cultivation. The study aimed to establish the indicator leaf and its critical greenness for in-season management of fertilizer nitrogen (N) in Bt cotton using chlorophyll (SPAD) meter and leaf color chart (LCC). The response of three varieties and N treatments viz. 0, 30, 60, 90,120, 150 and 180 kg N ha−1 applied in two splits {(50% at thinning and 50% at first flowering) and three splits (50% at thinning, 25% at first flowering and 25% at boll formation)} was studied through split plot design. SPAD values and LCC scores of first, second, third and fourth fully opened leaves from the top of the main stem was recorded at first flowering and boll formation. The physiological efficiency and harvest index was highest for 90 Kg N ha−1 applied in two splits. Beyond 120 kg N ha−1, the N use efficiency parameters were higher for the N treatments applied in three split compared to the respective two split N treatments. The fourth leaf from the top in terms of SPAD values and LCC scores correlated best with N concentration compared to other leaves at all growth stages. The calculated critical SPAD values for the fourth leaf were 45 and 41 at first flowering and boll formation, respectively. Critical score of fourth leaf was 4.1 and 4, respectively at first flowering and boll formation, respectively. It is suggested that color of the fourth leaf from the top of Bt cotton can well indicate N supply from the soil and can help in need based N management.

Information about the Effect of Climatic Factors and Soil Moisture Status on Cotton Production using Different Statistical Relations

Understanding the impacts of climatic factors on cotton production may help physiologists to determine the control mechanisms of boll retention in cotton. However, weather affects crop growth interactively, sometimes resulting in unexpected responses to prevailing conditions. Field trials, 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, i.e., daily data of maximum air temperature (°C), minimum air temperatures (°C), maximum-minimum temperature (diurnal temperature range or temperature magnitude) (°C), sunshine duration (hd-1), maximum humidity (%), minimum humidity (%) and wind speed (ms-1). It could be generally concluded that minimum humidity (water stress) and sunshine duration, were the most significant climatic factors affecting cotton flower and boll production and retention in Egyptian. Temperature appeared to be less important in the reproduction growth stage of cotton in Egypt than minimum humidity and sunshine duration. The soil moisture status showed low and insignificant correlation to flower and boll production. The positive correlation between minimum humidity value along with the negative correlation between each ofhigh maximum air temperature(temperature equalled or exceeded 37.5°C) and sunshine duration with flower and boll formation, indicate that high value of minimum humidity, short period of sunshine duration and low value of temperature would enhance flower and boll formation.

Gas exchanges and production of colored cotton irrigated with saline water at different phenological stages

Scarcity of good-quality water is a limiting factor for irrigated agriculture, especially in semi-arid regions, which leads to the use of water with high salt content to irrigate crops. Therefore, this study aimed to evaluate physiological aspects and production of colored cotton genotypes under saline stress, during the different development stages and under conditions of low and high salinity. The experiment was conducted using a randomized block design, with a 3 × 7 factorial scheme and three replicates. Treatments corresponded to three colored cotton genotypes irrigated with low-salinity water (0.8 dS m-1) and high-salinity water (9.0 dS m-1): T1-A1B1C1, T2-A2B1C1, T3-A1B2C1, T4-A1B1C2, T5-A2B1C2, T6-A2B2C1 and T7-A1B2C2 (A1, B1 and C1: without salinity and A2, B2 and C2: with salinity; in the vegetative, flowering and fruiting stages, respectively). Among the genotypes, BRS Rubi was the most sensitive to irrigation water salinity, regardless of development stage. Successive application of saline water at the flowering and boll formation stages led to drastic reduction in physiological aspects of the crop, with recovery of the plants after the stress was interrupted. Saline water irrigation at initial development stages can be used in the cotton crop for reducing the average time to the beginning of flowering. Seed cotton production was more affected by application of saline water at the flowering and boll formation stages.

Carbohydrate metabolism in the subtending leaf cross-acclimates to waterlogging and elevated temperature stress and influences boll biomass in cotton (Gossypium hirsutum).

Short-term waterlogging and chronic elevated temperature occur concomitantly in the cotton (Gossypium hirsutum) growing season. While previous research about co-occurring waterlogging and elevated temperature has focused primarily on cotton fiber, no studies have investigated carbohydrate metabolism of the subtending leaf (a major source leaf for boll development) cross-acclimation to aforementioned stressors. To address this, plants were exposed to ambient (31.6/26.5°C) and elevated (34.1/29.0°C) temperatures during the whole flowering and boll formation stage, and waterlogging (0, 3, 6 days) beginning on the day of anthesis. Both waterlogging and high temperature limited boll biomass (reduced by 1.19-32.14%), but effects of different durations of waterlogging coupled with elevated temperature on carbohydrate metabolism in the subtending leaf were quite different. The 6-day waterlogging combined with elevated temperature had the most negative impact on net photosynthetic rate (Pn) and carbohydrate metabolism of any treatment, leading to upregulated GhSusA and GhSusC expression and enhanced sucrose synthase (SuSy, EC 2.4.1.13) activity for sucrose degradation. A prior exposure to waterlogging for 3 days improved subtending leaf performance under elevated temperature. Pn, sucrose concentrations, Rubisco (EC 4.1.1.39) activity, and cytosolic fructose-1,6-bisphosphatase (cy-FBPase, EC 3.1.3.11) activity in the subtending leaf significantly increased, while SuSy activity decreased under 3 days waterlogging and elevated temperature combined relative to elevated temperature alone. Thus, we concluded that previous exposure to a brief (3 days) waterlogging stress improved sucrose composition and accumulation cross-acclimation to high temperature later in development not only by promoting leaf photosynthesis but also inhibiting sucrose degradation.

Potassium fertilizer improves drought stress alleviation potential in cotton by enhancing photosynthesis and carbohydrate metabolism

Under drought, limited photo-assimilates synthesis and their poor partitioning is a main constraint to final yield production in cotton (Gossypium hirsutum L.). To study the potassium (K) role in photo-assimilation and carbohydrate metabolism in cotton under soil drought stress during flowering and boll formation stage, a two-year pot experiment was conducted in 2015 and 2016. Two cotton cultivars namely Simian 3 (low-K tolerant) and Siza 3 (low-K sensitive) were grown under three K rates (0, 150 and 300kgK2Oha−1). Plants were exposed to well-watered [(75±5%) soil relative water content (SRWC)] and water stress (35–40% SRWC) for 7days followed by re-watering to SRWC (75±5%). The results showed that water-stressed plants under K0 application exhibited significant decline in net photosynthesis, stomatal conductance, intercellular CO2 concentration and ribulose-1,5-bisphosphate carboxylase (Rubisco) activity and resulting in reduced photo-assimilates synthesis and partitioning towards reproductive organs in both cultivars. Conversely, K application decreased the decline in photosynthesis, Rubisco activity and biomass accumulation and partitioning. The positive effects of K application increased as increasing K rates, and that was more pronounced in Siza 3 than Simian 3. Drought stress decreased starch content but increased sucrose content; whereas, K application maintained higher concentration of sucrose in leaves of water-stressed plants through the regulation of higher sucrose phosphate synthase (SPS), sucrose synthase (SuSy) and lower soluble acid invertase (SAI) activities. The results of the study concluded that K application regulated the photo-assimilation and translocation process along with the related enzymes activities in cotton. The study suggests that K nutrient management strategy has the potential to minimize the impacts of drought stress in cotton.

Gene expression in response to Cotton Leaf Curl Virus infection in Gossypium hirsutum under variable environmental conditions

Cotton Leaf Curl Disease (CLCuD) is one of the threatening constrains of cotton production in Pakistan for which no adequate remedy is available until now. Local variety of Gossypium hirsutum (FH-142) was grown in field and infected naturally by CLCuV under variable range of temperature and humidity. Plants showed thickening of veins in lower leaf surface at 34?C and 60% relative humidity at 15days post infection (dpi) and curling of leaf margins at 33?C with 58% relative humidity at 30dpi. Remarkable leaf darkening was observed with reduced boll formation at 45dpi at 26?C and 41% relative humidity. Enation developed, severe thickening and curling of leaves intensified and plants showed dwarf growth at 60dpi at 24?C with 52% relative humidity. PCR amplification of Rep associated gene confirmed the presence of CLCuD-associated begomovirus in the infected samples. Quantitative RT-PCR confirmed the amplification and differential expression of a number of pathogen stress responsive genes at different levels of temperature and humidity. This observation predicts that Cotton Leaf Curl Virus (CLCuV) interacts with several host genes that are upregulated to make plants susceptible or suppress other genes to overcome host defense responses.