Editing IPCC:AR6/SRCCL/Chapter-3 (section)

==== 3.6.1.5 Use of halophytes for the re-vegetation of saline lands ====

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Soil salinity and sodicity can severely limit the growth and productivity of crops (Jan et al. 2017 <sup>[[#fn:r1119|1119]]</sup> ) and lead to a decrease in available arable land. Leaching and drainage provides a possible solution, but can be prohibitively expensive. An alternative, more economical option, is the growth of halophytes (plants that are adapted to grow under highly saline conditions) that allow saline land to be used in a productive manner (Qadir et al. 2000 <sup>[[#fn:r1120|1120]]</sup> ). The biomass produced can be used as forage, food, feed, essential oils, biofuel, timber, or fuelwood (Chughtai et al. 2015 <sup>[[#fn:r1121|1121]]</sup> ; Mahmood et al. 2016 <sup>[[#fn:r1122|1122]]</sup> ; Sharma et al. 2016 <sup>[[#fn:r1123|1123]]</sup> ). A further co-benefit is the opportunity to mitigate climate change through the enhancement of terrestrial carbon stocks as land is re-vegetated (Dagar et al. 2014 <sup>[[#fn:r1124|1124]]</sup> ; Wicke et al. 2013 <sup>[[#fn:r1125|1125]]</sup> ). The combined use of salt-tolerant crops, improved irrigation practices, chemical remediation measures and appropriate mulch and compost is effective in reducing the impact of secondary salinisation ( ''medium confidence'' ).

In Pakistan, where about 6.2 Mha of agricultural land is affected by salinity, pioneering work on utilising salt-tolerant plants for the re-vegetation of saline lands (biosaline agriculture) was done in the early 1970s (NIAB 1997 <sup>[[#fn:r1796|1796]]</sup> ). A number of local and exotic varieties were initially screened for salt tolerance in lab – and greenhouse-based studies, and then distributed to similar saline areas (Ashraf et al. 2010 <sup>[[#fn:r1126|1126]]</sup> ). These included tree species ( ''Acacia ampliceps, Acacia nilotica, Eucalyptus camaldulensis, Prosopis juliflora, Azadirachta indica'' ) (Awan and Mahmood 2017 <sup>[[#fn:r1127|1127]]</sup> ), forage plants ( ''Leptochloa fusca, Sporobolus'' ''arabicus, Brachiaria mutica, Echinochloa'' sp., ''Sesbania'' and ''Atriplex'' spp.) and crop species including varieties of barley ( ''Hordeum vulgare'' ), cotton, wheat ( ''Triticum aestivum'' ) and ''Brassica'' spp. (Mahmood et al. 2016 <sup>[[#fn:r1128|1128]]</sup> ) as well as fruit crops in the form of date palm ( ''Phoenix dactylifera'' ) that has high salt tolerance with no visible adverse effects on seedlings (Yaish and Kumar 2015 <sup>[[#fn:r1129|1129]]</sup> ; Al-Mulla et al. 2013 <sup>[[#fn:r1130|1130]]</sup> ; Alrasbi et al. 2010 <sup>[[#fn:r1131|1131]]</sup> ). Pomegranate ( ''Punica granatum L.'' ) is another fruit crop of moderate to high salt tolerance. Through regulating growth form and nutrient balancing, it can maintain water content, chlorophyll fluorescence and enzyme activity at normal levels (Ibrahim 2016 <sup>[[#fn:r1132|1132]]</sup> ; Okhovatian-Ardakani et al. 2010 <sup>[[#fn:r1133|1133]]</sup> ).

In India and elsewhere, tree species including ''Prosopis juliflora, Dalbergia sissoo'' , and ''Eucalyptus tereticornis'' have been used to re-vegetate saline land. Certain biofuel crops in the form of ''Ricinus communis'' (Abideen et al. 2014 <sup>[[#fn:r1134|1134]]</sup> ), ''Euphorbia antisyphilitica'' (Dagar et al. 2014 <sup>[[#fn:r1135|1135]]</sup> ), ''Karelinia caspia'' (Akinshina et al. 2016 <sup>[[#fn:r1797|1797]]</sup> ) and ''Salicornia'' spp. (Sanandiya and Siddhanta 2014 <sup>[[#fn:r1136|1136]]</sup> ) are grown in saline areas, and ''Panicum turgidum'' (Koyro et al. 2013 <sup>[[#fn:r1137|1137]]</sup> ) and ''Leptochloa fusca'' (Akhter et al. 2003 <sup>[[#fn:r1138|1138]]</sup> ) have been grown as fodder crop on degraded soils with brackish water. In China, intense efforts are being made on the use of halophytes (Sakai et al. 2012 <sup>[[#fn:r1139|1139]]</sup> ; Wang et al. 2018 <sup>[[#fn:r1140|1140]]</sup> ). These examples reveal that there is great scope for saline areas to be used in a productive manner through the utilisation of halophytes. The most productive species often have yields equivalent to conventional crops, at salinity levels matching even that of seawater.

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