Antioxidant and Physiological Responses of Upland Cotton Accessions Grown Under High-Temperature Regimes

Increased temperature caused by climate change is exerting negative impacts on productivity of cotton crop. Therefore, breeding cultivars tolerant of high temperature are need of the time. Realizing the situation, 154 accessions of upland cotton were sown under alpha lattice design in three replications in two sowing dates. The first sowing date was planned to coincide the flowering stage with maximum annual temperature (± 48 °C) of the region. The data were recorded at appearance of first flower for physiological traits like viability of pollen grains and cell membrane thermostability. Enzymatic and non-enzymatic antioxidants, i.e., peroxidase activity and proline contents were also quantified along with hydrogen peroxide. K-means cluster and biplot analysis revealed the differential response of genotypes. FH-Lalzar, IUB-13, GH-Mubarak and Shahkar exhibited higher values for antioxidants and physiological traits. The yield and fibre quality of these genotypes were also superior as compared to others. It was suggested that diversity in germplasm for aforementioned traits can be utilized in further breeding programs.

  • Sajid Majeed, Tanwir Ahmad Malik, Iqrar Ahmad Rana, Muhammad Tehseen   AzharEmail author

Iranian Journal of Science and Technology, Transactions A: Science

Transgenic crops for the agricultural improvement in Pakistan

Transgenic technologies have emerged as a powerful tool for crop improvement in terms of yield, quality, and quantity in many countries of the world. However, concerns also exist about the possible risks involved in transgenic crop cultivation. In this review, literature is analyzed to gauge the real intensity of the issues caused by environmental stresses in Pakistan. In addition, the research work on genetically modified organisms (GMOs) development and their performance is analyzed to serve as a guide for the scientists to help them select useful genes for crop transformation in Pakistan. The funding of GMOs research in Pakistan shows that it does not follow the global trend. We also present socio-economic impact of GM crops and political dimensions in the seed sector and the policies of the government. We envisage that this review provides guidelines for public and private sectors as well as the policy makers in Pakistan and in other countries that face similar environmental threats posed by the changing climate.


Recent advancements in biotechnology resulted in rapid adoption of genetically modified (GM) crops in the agriculture systems. At the same time, transgene escape has also been reported and examples reveal global dimension of the problem. Pollen mediated gene flow (PMGF) is the major pathway for transgene escape. Almost all transgenes have been escaped into their Non-GM counterpart and wild relatives. Although gene flow varies between species, crops, and ecological zones/environments but intraspecific gene flow (> 10%) is not uncommon in adjacent populations. Whereas in outcrossing species, 1% gene flow at thousand meters’ isolation is not unusual, and magnitude is even higher than the mutation rate. It is well documented that transgene flow is deteriorating different production systems in agriculture and famers choice to cultivate GM, conventional and organic crops. If comprehensive policy is not implemented, then in future it will be difficult to detect and remove transgenes from the environment; if unexpected problems arise.

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

Cotton belongs to family Malvaceae containing more than
200 genera and about 2 300 species. There are more than
50 species of Gossypium reported till now, which are native
to Africa, Australia, Central and South America and Asia,
respectively (Fryxell 1992; Wendel and Grover 2015). Out
of 50 species, only four are domesticated and widespread.
Two diploid (2n = 26) species, namely G. arboreum and G.
herbaceum belong to Old World cotton produce only 1%
of the total cotton production in the world, whereas two
tetraploid (2n = 52) species, namely G. barbadense and G.
hirsutum belong to New World cotton produce 94% of the
total world cotton production. G. barbadense produces 4%,
while G. hirsutum also known as upland cotton produces
about 90% of the total cotton production in the world (Lu
et al. 1997; McCarty et al. 2004).
Upland cotton is a key source of spinnable fiber and cultivated
in more than 61 countries in the world on an area of
29.3 million hectares (ICAC 2018). Cotton and cottonbased
industry has a pivoting role in the economy of
Pakistan. Pakistan ranks the fourth in terms of area and
production in the world after India, China and USA, 3rd in
consumption and 2nd in yarn production in the world.
Cotton contributes 1% share in GDP, while 55% in total foreign
exchange earnings of Pakistan. Cotton was planted on
an area of 2.7 million hectares in 2017, showing an increase
of 10% over the previous year. About 8% more cotton production,
i.e., 11.54 million bales was recorded during 2017/
2018 as compared with 2016/2017 where 10.72 million
bales was recorded (PCCC 2017). However, in terms of per
acre yield (679 kg·hm− 2), Pakistan is lagging far behind
from the major cotton producing countries like Australia
(1 816 kg·hm− 2), China (1 719 kg·hm− 2), Turkey (1 826
kg·hm− 2) and USA (985kg·hm− 2) (ICAC 2018).
A loss of about one-third of cotton produce was recorded
in Pakistan during 2015/2016 due to adverse climatic conditions
particularly heavy rains during reproductive phase
of crop. But high temperature with dry weather conditions
favored the spread of whitefly in 2016 and 2017 which affected
the productivity of cotton crop on a wide range of
area in Punjab province. In recent times besides drought,
salinity, insect pests, diseases and seed quality: high
temperature has emerged as a major threat to cotton productivity.
It is estimated that the global temperature is increasing
by 0.4~0.8 °C/year (PMD 2016). The consequences
of high temperature in cotton could be low germination,
higher fruit shedding (≥ 30 °C/22 °C), pollen sterility and
abortion (Guilioni et al. 1997; Ismail and Hall 1999), unavailability
of macro and micro nutrients due to increase in
soil pH, higher levels of CO2 in the air will increase photosynthetic
activity resulting in enhanced nutrient requirement
of cotton plants.

Role of SNPs in determining QTLs for major traits in cotton

A single nucleotide polymorphism is the simplest form of genetic variation among individuals and can induce
minor changes in phenotypic, physiological and biochemical characteristics. This polymorphism induces various
mutations that alter the sequence of a gene which can lead to observed changes in amino acids. Several assays
have been developed for identification and validation of these markers. Each method has its own advantages and
disadvantages but genotyping by sequencing is the most common and most widely used assay. These markers are
also associated with several desirable traits like yield, fibre quality, boll size and genes respond to biotic and abiotic
stresses in cotton. Changes in yield related traits are of interest to plant breeders. Numerous quantitative trait loci
with novel functions have been identified in cotton by using these markers. This information can be used for crop
improvement through molecular breeding approaches. In this review, we discuss the identification of these markers
and their effects on gene function of economically important traits in cotton

Mep Plus – A Newly Registered PGR

MepPlus is a premix of Mepiquat Chloride and Bacillus cereus (BP01). It gained full EPA registration in 1997 for use on cotton. The B. cereus component has a tolerance exemption on all crops. MepPlus was extensively tested by university researchers across the US cotton belt in 1996 and 1997. It provides both significantly higher lint yield and more consistent yield increases than Mepiquat Chloride alone while producing the same degree of earliness and growth control. It was introduced in the US commercially late in the 1997 season. Yield results and preliminary information on the possible mode of action are provided.

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Effect of Four Growth Regulators

The effect of four plant growth regulators (PGRs) on crop performance, fruiting pattern, yield and fiber quality in cotton (Gossypium hirsutum L.) was evaluated in field experiments for two years in Greece. All four PGRs (Cytokin, Cytoplex, PHCA and Atonic) increased seedcotton yield and differences were related to effects on plant growth and development. Number of sympodia with 2 bolls and total boll number increased significantly in the Cytokin and Cytoplex treated plants, while Atonic and PHCA had a lesser effect. All PGRs increased boll retention, either at first or at second position. Lint quality was not affected by PGRs, although in some experiments positive effects were found in fiber maturity and strength. It is concluded that the four PGRs have the potential to control plant growth and enhance yield.

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PGR IV Increased Cotton Yield by Affecting Various Fruiting Parameters

The effect of the plant growth regulator PGR-IV on cotton (Gossypium hirsutum) was evaluated in field experiments in up to eight locations, for three years (1995-97) in Greece. Seedcotton yields were increased by up to 20 % in most locations, compared to the control. The mean yield increase in all locations and years was 4.9%. This was correlated with increases in boll retention, number of sympodia with two bolls and total boll number per plant. Late PGR-IV applications had no significant effect on seedcotton yield, compared to the PGR-IV treatment with three applications. No effect was found in plant height and fiber quality parameters. It is concluded that PGR-IV can increase seedcotton yield by affecting plant performance.

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Heat Tolerance of Cotton Genotypes Assessed by Electrolyte Leakage, Chlorophyll Fluorescence Analysis and Performance in the Field in Pakistan

Germination and emergence of 117 cotton accessions were tested in the laboratory at 43oC and 30oC. The absolute heat tolerance of detached leaves of the 117 accessions was tested by chlorophyll fluorescence analysis (CFA) and by electrolyte leakage tests. The heat tolerance of whole plants was examined in a large, modified growth chamber. The relationships between temperature, net photosynthesis, stomatal conductance, transpiration and transpirational leaf cooling were examined using an automated CIRAS infra-red gas analyzer to measure gas exchange parameters while applying defined profiles of increasing leaf temperatures. An early-sowing field experiment at Multan examined the responses of 16 cotton lines to early heat stress. CIM443, CIM 438, BH89, GH8, NIAB78 SLS1 and 1269/93 were more heat-tolerant than Acala SJ2 at the germination stage. The chlorophyll fluorescence assay (CFA) revealed that CIM448 and CIM435 performed better than CIM443, but SLS1 performed badly in CFAs. Of the wild species, G. sturtianum was least tolerant, while Thespesia populnea was the most heat-tolerant wild relative. The hexaploid G411 (G. hirsutum cv. NC8 x G. australe) was the most tolerant interspecific hybrid. Electrolyte leakage tests largely confirmed these results. CIM448 and NIAB 313 were less leaky than Acala SJ2, while DNH40 was susceptible to heat damage. Only the electrolyte leakage test gave data which correlated well with yields in the field experiment.

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Glycinebetaine Treatment Improves Cotton Yields in Field Trials in Pakistan

This study was designed to test the effectiveness of glycinebetaine (an osmoprotectant purified from sugar beet and applied as a spray of ‘Greenstim’) in improving the yields of cotton under normal cultivation conditions in the Punjab of Pakistan. Field trials were conducted in replicated small plots at two sites over two years to determine the optimal timing and dose of glycinebetaine. CIM-240 was sown in 1996 at the Postgraduate Agricultural Research Station (PARS), Faisalabad but was badly affected by whitefly and cotton leaf curl virus. CIM-443 was sown in 1996 and 1997 at the Central Cotton Research Institute (CCRI), Multan. This was resistant to leaf curl virus, and was sown at PARS in 1997. Generally, glycinebetaine concentrations and time of application had little effect on physiological parameters. In 1996, glycinebetaine concentrations were significantly increased in the trial at Faisalabad, but not at Multan. In 1996 the highest yield of seed cotton at Faisalabad (136 % of the control) was obtained with 3-kg/ha glycinebetaine applied at squaring. At Multan, seed cotton yields were highest with 3 and 6 kg/ha glycinebetaine applied at squaring. Glycinebetaine dose and time of application had highly significant (P<0.001) effects on yield, total dry matter and bolls per plant. Glycinebetaine-treated plants also had more nodes at maturity than the controls. Mean boll weight, % flower and boll shedding were not affected. In 1997 the highest yields were obtained when glycinebetaine was applied at first flowering at PARS, but at the pre-squaring stage at CCRI.

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