Raziuddin Ansari

The place of halophytes in Pakistan’s biofuel industry

An unsustainable supply of fossil fuel necessitates the need to look for suitable alternatives. One solution lies in using plant biomass, which can be converted into a wide range of biofuels. To avoid conflict between feed and fuel, the crops available for human consumption being used presently as biofuel feedstock may be replaced with halophytes, which have the potential to thrive in saline lands and can be irrigated with brackish water; some can even tolerate seawater salinity. This approach will help in producing sustainable fuel without encroaching on the good quality land and water resources needed for food crops. A candidate species should preferably be perennial, having high yield in saline lands with minimum inputs. Other attributes include cellulose/hemicellulose >25–30%, lignin <10%, low salt load in foliage and a non-invasive nature. The unexplored aspects of agronomy of these wild plants need careful study, especially with regards to land degradation and ecological consequences, before large-scale cultivation.

Dormancy and germination responses of halophyte seeds to the application of ethylene.

Ethylene is invariably produced during seed germination but its role in regulating seed dormancy and germination is poorly understood. Seeds of 22 halophytic species having different life forms - salt secreting dicots, salt secreting monocots, stem succulents and leaf succulents were germinated in Petri dishes kept in a growth chamber set at 20/30 degrees C (night/day) temperature and a 12 hr light period. Sodium chloride and ethephon were added to the medium from the beginning of the experiment. Seed germination was recorded every other day for twenty days. Application of ethylene did not have any significant effect on releasing seeds from innate dormancy. However, it appeared to have a role in alleviation of salinity effects which varied from negative in certain species to almost complete alleviation of high salinity effects in others. Our data indicates that ethylene appears to have little role in breaking innate seed dormancy however, in most halophyte seeds studied, application of ethylene alleviate the salinity effect to various degrees. Halophyte seeds which could germinate under saline conditions approaching twice the salinity of seawater may offer clues to understand management of seed germination under highly saline conditions.

Halophytic biofuels revisited

575 ISSN 1759-7269 10.4155/BFS.13.57

Potential use of halophytes with emphasis on fodder production in coastal areas of Pakistan

Fresh water resources both for domestic and agricultural use are constantly depleting worldwide and crop yields suffer from a steady increase in soil salinity, especially in the arid and semi-arid areas. A burgeoning world population is a further threat to sustained food supply. Equally or even more affected in some cases, are other resources like fodder for animals and fuel wood for the rural poor. Efforts are hence needed to find an alternate source of water and utilization of saline lands for economic benefit. The varied climatic conditions of Pakistan offer opportunities for selecting suitable halophytes for specific purposes. Whereas halophytes may be used for a variety of purposes like food, fiber, fuel wood, medicines, source of chemicals, landscaping, ornamental, carbon sequestration, etc., one of the very important utilities lies in their use as fodder. An animal feeding trial showed that traditional green fodder (maize) and a halophytic grass (Panicum) were equally good for growth and development of 1-year-old cow calves. Meat from animals fed 100% Panicum was leaner and hence better for human consumption from health point of view.

Effect of ascorbic acid on seed germination of three halophytic grass species under saline conditions

Grasses on the Pakistani coast are moderately to highly salt tolerant and have potential for utilization as a cash crop. This study was designed to determine whether seed germination of three halophytic grasses (Phragmites karka, Dichanthium annulatum and Eragrostis ciliaris) could be improved by exogenous application of ascorbic acid (AsA) under saline conditions. Seeds of P. karka were germinated in varying concentrations of NaCl and AsA under different temperature regimes, and seeds of Dichanthium annulatum and Eragrostis ciliaris were germinated at optimal temperatures only. In P. karka, concentrations of AsA (5 and 10 mM) alleviated the salinity effects better at cooler and moderate thermo-periods, whereas higher concentrations (20 mM of AsA) failed to improve germination under all temperature regimes. AsA was ineffective at a warmer thermo-period (25/35°C). The rate of germination also increased at all thermo-periods with the application of AsA except at 25/35°C under saline conditions. Application of AsA improved the germination of E. ciliaris seeds under saline conditions but was inhibitory for D. annulatum in comparison with the untreated control. The rate of germination followed the similar pattern as that of seed germination. Results indicate that AsA has the ability to partially alleviate the effect of salinity on seed germination of some grass species under optimal temperature regime.

Importance of the Diversity within the Halophytes to Agriculture and Land Management in Arid and Semiarid Countries

Freshwater resources will become limited in near future and it is necessary to develop sustainable biological production systems, which can tolerate hyper-osmotic and hyper-ionic salinity. Plants growing in saline conditions primarily have to cope with osmotic stress followed by specific ion effects, their toxicities, ion disequilibrium and related ramifications such as oxidative burst. This is an exclusion criterion for the majority of our common crops. In order to survive under such conditions, suitable adjustments are necessary. Beside the control of the entrance on root level, the ability to secrete ions (excreter) or to dilute ions (succulents) helps to preserve a vital ion balance inside the tissues.

Oilseed halophytes: a potential source of biodiesel using saline degraded lands

The financial and technical aspects of using edible plants as a biodiesel source have been studied extensively, but research on the potential use of salt resistant, non-edible plants for this purpose remains relatively underexplored. Data available on salt tolerance range, seed oil content, composition of fatty acid methyl esters (FAME) and engine performance parameters – Iodine Value (IV), Cetane Number (CN) and Saponification Number (SN) – of 20 salt-resistant plants were examined to assess their suitability for use as diesel engine fuel. Most of the test species were perennial from family Amaranthaceae, exhibiting high salt tolerance. The quantity of their seed oil ranged from 10–30% while nine species contained >25% oil. The SN, IV and CN values varied from 130–206, 29–156 and 38–81, respectively. Based on the above mentioned parameters, seven halophytic plant species – Salicornia fruticosa, Cressa cretica, Arthrocnemum macrostachyum, Alhagi maurorum, Halogeton glomeratus, Kosteletzkya virginica and Atriplex rosea – appear to be promising biodiesel candidates. These non-food plants which can grow using saline resources and have an oil composition suitable for engine efficiency are more salt resistant than Jatropha or other glycophytic feedstock to serve in a bioenergy farming system. Cultivation of such plants for biodiesel production has the additional advantage of reclaiming degraded lands with the environmental benefit of carbon sequestration.

Salinity improves growth, photosynthesis and bioenergy characteristics of Phragmites karka

Abstract. Based on biomass composition of plants collected from saline habitats, Phragmites karka (Retz.) Trin. ex Steud. has emerged as a suitable feedstock for biofuel. In the present study, plant growth, eco-physiological responses and bioenergy characteristics of P. karka grown under conditions ranging from non-saline to ∼80% seawater salinity are reported. Moderate salinity (NaCl at 100 mol m–3) increased plant fresh weight (20%), number of leaves (25%) and specific plant length, which were directly linked with increased net photosynthetic rate (25%) and stomatal conductance (25%) compared with the non-saline control. Higher photosynthetic efficiency was achieved by increasing electron transport rate (ETR, 20%), effective quantum yield (YII, 21%) and maximum efficiency of photosystem II (Fv/Fm, 20%). Decreased non-photochemical quenching (Y(NPQ)) and malondialdehyde content (18%) indicated an oxidative balance, which was also reflected in total carotenoids and chlorophylls. These eco-physiological parameters worked together to increase cellulose (34%) and hemicellulose (70%) at NaCl concentrations up to 200 mol m–3. Decreased growth under higher salinity could be linked with photosynthesis inhibition, due to stomatal closure and co-occurring reduction in CO2 uptake. Lower stomatal conductance increased water-use efficiency but led to over-production of reactive oxygen species, which disturbed oxidative stability (increasing ETR/PN) and imposed membrane leakage. Consequently, plants accumulated more carotenoids and soluble carbohydrates to stabilise PSII machinery (Fv/Fm, YII and Y(NPQ)), and to survive under high salinity. Such adaptations, however, led to growth penalty and reduced quality of lignocellulosic biomass. The above findings suggest that P. karka qualifies as a suitable raw material for biofuel under moderate salinity.

POTENTIAL OF HALOPHYTES AS CATTLE FODDER: A CASE-STUDY IN PAKISTAN

Good quality water and arable land are needed to grow conventional crops to provide food for human and animal population. However, burgeoning world population leading to wide spread urbanization and industrialization is aggressively sharing these resources. A solution may be found in using saline water and salinized lands to produce quality animal feed from salt tolerant plants. In this study, two halophytic grasses (Panicum antidotale and Desmostachya bipinnata) were tested for their potential to replace conventional cattle fodder in the diet of cattle. Four trials were conducted in which cow calves were fed diets containing above mentioned halophytes alone or in combination with conventional fodders (wheat and maize). Weight gain in animals fed diets supplemented with halophytes were generally at par with or in few cases marginally better than those on conventional fodder. For instance, P. antidotale increased the calf weight around 15% when used as green and 8% in case of hay. Feeding Berseem (Trifolium alexandrinum, 15% crude protein) as the only source of concentrate in a diet containing D. bipinnata sustained weight only for about 6-7 weeks after which it started to decrease. Supplementing the diet with a regular concentrate was subsequently needed to restore weight gain. Halophytes as green/hay/concentrate were as good as conventional fodder regarding dressed meat. The protein content of meat was showing increasing trend when replacing conventional fodders with halophytes, particularly 20% protein was higher in meat when Prosopis juliflora pods and Manilkara zapota were used as concentrate and P. antidotale as hay in diet.