Zarai Digest, October-December 2019

AQUATIC WEEDS IN PAKISTAN AND THEIR MANAGEMENT Dr. Muhammad Ashfaq Wahid, Dr. Muhammad Farrukh Saleem, Dr. Haroon Zaman Khan and Dr. Zahid Ata Cheema, Department of Agronomy, University of Agriculture, Faisalabad.

Aquatic plants can be found in, on Pakistan. The rapid increase and spread of and around water bodies. These plants range the plant into new areas is particularly due to from microscopic organisms (plankton its ability to reproduce from its vegetative algae, which remains suspended in the parts; a single plant can invade the whole water) to larger plants rooted in the bottom lake or pond rapidly. Its rapid growth of ponds. Certain types of aquatic plants are oftenly leads to dense mats across the water essential for fish production. Nonetheless, surfaces that affect the water quality by the aquatic plants interfering with human reducing the quantity of oxygen and sunlight interests are considered weeds. These plants penetration thus resulting in the death of fish invade lakes, ponds, rivers, canals and and other aquatic organisms. These large agricultural fields, which make them mats also act as breeding places for noxious. Abundance of these weeds creates mosquitoes. hazards to aquatic life, act as breeding Management places for mosquitoes, cause hindrances to Different ways for managing water water sports, damage the environment and hyacinth will be discussed in the following economy and deteriorate recreational and lines. Out of different control methods, scenic beauty of the lakes. Aquatic weeds biological control is considered the long- may be categorized into four groups viz. term, sustainable, economic, and safe algae, floating weeds, emersed weeds solution for large infestations. Many (foliage above water) and submersed weeds. Arthropod species like Weevils (Neochetina Water hyacinth, cattail, giant reed, bruchi, Neochetina eichhorniae), moths and water lettuce etc. are major weeds found (Xubida infusellus, and Niphograpta in water bodies in Pakistan. Like terrestrial albiguttalis, syn. Sameodes albiguttalis), weeds, aquatic weeds may also be managed mites (Orthogalumna terebrantis) and bugs by following preventive, mechanical, (Eccritotarsus catarinensis) can be used as biological and chemical means. The biological control agents. They keep the development of an aquatic weed weed under control by eating it. Once the management plan however depends on plant infestation is reduced in size, the insect correctly identifying the problem weed(s) population dies down. When the plant and selecting the most suitable control begins to spread again, the insects naturally methods. This article gives an account of increase in number and the cycle continues. important aquatic weeds in Pakistan control Biological control alone is unlikely to be thereof. successful for controlling water hyacinth, so Water Hyacinth (Gul-e-Bakoli) it is important to integrate it with other Water hyacinth or Gul-e-Bakoli control techniques thus making it (Eichhornia crassipes), though native to the sustainable and affordable. Herbicides have Amazon basin and Brazil, became long been used to control water hyacinth. widespread throughout the world. It is Although the herbicides can effectively considered one of the worst aquatic weeds in control large infestations, they do not the world and is commonly found in provide a sustainable control and pose a

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Zarai Digest, October-December 2019 potential threat of polluting the water. So the considered another effective control method use of herbicides should be limited to areas because these plants are highly sensitive to of high infestations and treated water should shade. At seedling stage the best possible not be used for drinking water. In case it method is manual or mechanical uprooting becomes inevitable to use chemical then of the plants. KWH02 (asexual reproduction inhibitor) can Different chemical control measures be used. Herbicide glyphosate, 2,4-D and can also be used against cattails including paraquat (aquatic formulations) have been use of chemicals like dalapon, glyphosate, used for controlling water hyacinth in many atrazine and paraquat. Using herbicides parts of the world. The management of when flowering has been found to cause the weeds mass killed by herbicides is very greatest stress in typha. Proper arrangements important because it can decrease oxygen in should be made for the removal of dead water that may affect fish populations. plants because they can cause water to go Main problem in developing countries like foul and unusable. The cost involved in the Pakistan is lack of awareness about the management of catail is so high for both the harmful effects of this weed. In case of economy and ecology that economically large-scale water hyacinth infestations, it sustainable and environmentally safe will be necessary to reduce the coverage of controls should be used in order to provide the weed by means of chemical and/or long-term solutions to heavy weed mechanical control, and at the same time by infestations. An integrated control program introducing some biological control agents. should be structured for its successful Cattail or Typha (Dibb) management. Cattail (Typha angustata) commonly Giant Reed (Nara grass) known as dibb, is an emergent aquatic weed Giant reed (Arundo donax) locally and causes serious problems in the water called nara grass, is a native to the countries carriageways of Pakistan. It is widely surrounding the Mediterranean Sea. It can distributed in waterlogged areas and along rapidly invade stream banks and roadside irrigation/drainage channels threatening to habitats from a few individuals. Once impede the flow. Cattails spread rapidly by established, it has a strong ability to rhizomes and by small, airborne seeds that outcompete and completely suppress native may remain viable for 5 years or more. vegetation. In some areas, it may totally Management invade irrigation ditches as to reduce their Various methods can be adpted to water-carrying capacity in addition to large control the infestations of cattail. Permanent volumes of water being used for its own management of cattail is its replacement growth. with paragrass that can be used as fodder. Management Management with fire and physical removal Since giant reed mostly spreads by in conjunction with flooding are considered dispersal of rhizome fragments so removal most appropriate. In this practice cattails are of the entire rootstock is necessary to burned after drainage with subsequent deep overcome its populations. Its control flooding. Similarly, effective control of measures involve prevention, eradication cattail can also be achieved by a and control. Manual methods use hand labor combination of manual or mechanical to remove giant reed but these are very labor cutting of stems followed by submergence intensive due to large masses of rhizomes. of the remaining stems. Shading of cattails Mechanized equipment can also be used to with black polyethylene tarps is also remove above ground plant parts. These

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Zarai Digest, October-December 2019 methods are often non-selective because all The green bug (Schizaphiz graminum) has the vegetation is removed. This method been observed to feed on giant reed. In cannot be used in marshy or slopy areas or France Phothedes dulcis caterpillars feed on in soils susceptible to compaction or it. Zyginidia guyumi uses giant reed as an erosion. Tractor-mounted mowers or scythes important food source in Pakistan. A moth can be used to remove the plants. It is faster borer Diatraea saccharalis has been and more economical than manual means reported to attack the plants of giant reed. but requires several cuttings before the In addition to all these control underground parts exhaust their reserve food measures there are several herbicide options supply completely. If only a single cutting is available, but translocating herbicides are to be made, the best time is at flowering. At generally considered best. They are able to this stage the reserve food supply in the kill the rhizomes, and thus minimize the re- roots is nearly exhausted, and new seeds sprouting. Glyphosate is an easy and have not yet been produced. In some parts of effective herbicide for spot-treatment that the world burning of the giant reed is done translocates to the rhizomes. Paraquat alone by prescribed burning or broadcast burning. at 0.72 kg/ha can effectively be used for its This can be accomplished after herbicide control. The spray of chemicals immediately application. As alone burning will not after cutting the stems gives better control prevent resprouting so it should be followed than foliar spray due to efficient by mechanical removal of rhizomes. translocation. Grazing by goats and sheep is also Integration of all the above-mentioned considered an effective control measure. control methods generally will give the most Sheep are considered better than goats effective, economical, and environmentally because they can survive extended periods sound long-term management of the weeds. on a strict diet of giant reed. Some In case several techniques to be used in biological control agents have also been combination, these should be compatible reported for the management of giant reed. with one another.

CRISPR-CAS9 SYSTEM-A LANDMARK IN GENOME EDITING OF PLANTS Muhammad Jabran, Adil Zahoor, Zeenat Niaz, Mahpara Shahzadi, M. Anayat Ullah, and Muhammad Amjad Ali, Department of Plant Pathology, University of Agriculture Faisalabad.

From the smallest single celled fastest, easiest and cheapest of the gene organism to the largest creation on earth, editing tool, responsible for this new wave every living thing is defined by its genes. of science. The DNA contained instruction manual for Surprisingly, CRISPR is actually a our cells. Four building blocks called bases natural process that’s long functioned as a are strung together in precise sequences bacterial immune system, originally found which tell the cell how to behave and form defending single celled bacteria and arches the bases forever every trait, but with recent against invading viruses. In 2012, American advancements in gene editing tools scientist biochemist Doudna and French can change fundamental features in the microbiologist Emmanuelle Charpentier organisms. They can develop resistance were first to describe that CRISPR Cas9 against diseases in crops. They can provide could be used for genome editing in Bacteria cure from genetic diseases. CRISPR is the against virus.

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Zarai Digest, October-December 2019

Naturally occurring CRISPR uses yield improvement, biotic and abiotic stress two main components, the first is small management. Many of the published articles DNA sequences called Clustered Regularly are considered as proof-of-concept studies Interspaced Short Palindromic Repeats or as they describe the application of simply CRISPR, the second is Cas9 or CRISPR/Cas9 system by knocking out CRISPR associated proteins which cut up specific reported genes playing an important DNA like molecular scissors. Once a virus role in abiotic or biotic stress tolerant invades a bacterium, Cas proteins cut out the mechanisms. Biotic stress imposed by segment of a viral DNA to stitch into the pathogenic microorganisms pose severe bacterium CRISPR region (Figure 1). Those challenges in the development of viral codes are then copied into short pieces diseaseresistant crops and account for more of RNA. In case of CRISPR, RNA binds to than 42% of potential yield loss and a special protein called Cas9. contribute to 15% of global declines in food production. CRISPR/Cas9-based genome editing has been utilized to increase crop disease resistance and also to improve tolerance to major abiotic stresses like drought and salinity. A brief detail of the use of CRISPR for genome editing in various crop species is presented here. In rice, by targeting ethylene Figure 1: Mechanism of action of CRISPR- responsive factor gene OsERF922, Cas9 system. resistance against its devastating diseases The resulting complexes act like such as Bacterial blight and Rice Blast has scouts, lacking onto free floating genetic been accomplished. In the same way, several material and searching for matched to the genes of bread wheat such as TaMLO-A1, virus. If the virus invades again the scout TaMLO-B1 and TaMLOD1 have been complexes recognize immediately and Cas9 targeted to develop resistance against swiftly destroys the viral DNA. Lots of powdery mildews. In maize, ARGOS8 gene bacteria have this type of defence has been subjected to mutations for the mechanism but in 2012, scientist proposed enhancement of grain yield under drought that how to hijack CRISPR to target not just stress. Moreover, CRISPR-mediated viral DNA, but any DNA in almost any targeting to ALS1 gene in potato has led to organism. For editing, scientist works in the the resistance against herbicides. Recently, lab and designed a guide RNA to match the gene, they want to edit and attaches to Cas9 resistance to Verticillium dahliae infestation has been reported through gene editing of like the viral RNA in the CRISPR immune system. The gRNA direct Cas9 to the target Gh14-3-3d gene. The resulting transgene- clean plants showed a high resistance and in gene and proteins molecular scissors cut the DNA. This is the importance of CRISPR future could be used as a germplasm to breed disease-resistant cotton cultivars. power, just by injecting Cas9 bind to a short piece of custom gRNA scientist can edit Nonetheless, genome editing through CRISPR-Cas9 system has been approved practically any gene in the genome. CRISPR/Cas9 method of gene quit well and efficient source for the betterment of crops but this technology also editing has been adopted in nearly 20 crop raises big ethical questions. species so far. For various traits including

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