EFFECT OF LEAD AND CHROMIUM ON GROWTH, PHOTOSYNTHETIC PIGMENTS AND YIELD COMPONENTS IN MASH BEAN [VIGNA MUNGO (L.) HEPPER]

Transcription

1 Pak. J. Bot., 38(5): , 26. EFFECT OF LEAD AND CHROMIUM ON GROWTH, PHOTOSYNTHETIC PIGMENTS AND YIELD COMPONENTS IN MASH BEAN [VIGNA MUNGO (L.) HEPPER] MUMTAZ HUSSAIN, MUHAMMAD SAJID AQEEL AHMAD * AND ABIDA KAUSAR Department of Botany, University of Agriculture Faisalabad, (384), Pakistan. Abstract A pot experiment was carried out to study the effect of lead and chromium on growth, chlorophyll contents and yield components in two mash bean [Vigna mungo (L.) Hepper] cultivars i.e. Fs-1 and Mash-97. Fourteen-day old plants were exposed to 2 or 4 mg L -1 lead or chromium whereas control plants were treated with distilled water only. Application of both lead and chromium caused a significant reduction in all growth parameters as compared with that of control. The extent of decrease in growth due to chromium compared with lead. Although high concentration of both metals in the rooting media drastically reduced all photosynthetic pigments, chromium application caused more reducing effect as compared to chromium. In addition, all yield attributes of both cultivars of mash bean reduced due to both metals in rooting medium. The sensitivity of mash bean to chromium was greater as compared to lead. In conclusion, mash bean cultivar FS-1 proved to be tolerant as it showed less reduction in growth, photosynthetic pigments and yield as compared to Mash-97. Keywords: lead, chromium, growth, photosynthetic pigments, yield Introduction Worldwide, metal contamination has extremely increased in the biosphere as a result of anthropogenic activities. This situation is alarming in the developing world where untreated waste water is extensively used for irrigation or is disposed off in water resources (UNIDO, 22). These metals are deposited in different soil profiles leading to long-term metal contamination. These metals are mostly absorbed by plants easily and prove toxic to plants that can be observed as growth retardation as a result of alterations in biochemical process like inhibition of enzyme activity, protein penetration and impaired nutrition etc. (Poschenrieder, 199; Arun at al., 25). In the recent era, lead (Pb) contamination has gained a considerable attention as a potent environmental pollutant. Significant increases in the Pb content of cultivated soils have been observed near urban and industrial areas where it tends to accumulate in the surface ground layer (de Abreu et al., 1998). Despite regulatory measures adopted in many countries to have a check on Pb input in the environment, it continues to be one of the most serious global environmental hazards in the developing world (Yang et al., 2). Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic dust and gases. Chromium exists in the environment in several different forms with more common forms as chromium (III) and chromium (VI). Chromium (III) occurs naturally in the environment and is an essential nutrient whereas chromium (VI) is * Corresponding author: Muhammad Sajid Aqeel Ahmad, sajidakeel@yahoo.com

2 139 HUSSAIN ET AL. generally produced by industrial processes. The impact of Cr contamination in the physiology of plants depends on the metal speciation, which is responsible for its mobilization, subsequent uptake and resultant toxicity in the plant system (Shanker et al., 25). Mash bean [Vigna mungo (L.) Hepper] is among the most important pulse crops of the world. It has great value as food, fodder and green manure. In addition to improving the soil fertility, it is a cheap source of protein for direct human consumption. Chemical analysis of mash bean seed indicates that it contains protein (2-24%), oil (2.1%), Fats (1-2%), carbohydrates and a fair amount of vitamin A and B (James, 1981). Thus it has a great potential to improve protein deficiency in human beings by providing a low cost protein. Keeping in view the increasing use of sewage water for irrigation and resultant excessive accumulation of lead and chromium in different soil profiles, it was of great importance to evaluate their toxic effects on growth, photosynthetic pigments and yield components in mash bean, a potential legume crop of Pakistan. Materials and Methods Ten seeds of the two cultivars [Fs-1 and Mash-97] were sown in plastic pots containing 1 kg sandy loam soil [ECe = 1.2 ds/m and ph = 7.95] and after germination thinned to leave four plants of similar size. Fourteen-day old plants were exposed to 2 and 4 mg L -1 of lead nitrate [Pb(NO 3 ) 2 ] or chromium chloride [CrCl 3.6H 2 O] dissolved per liter distilled water, while control plants were treated with distilled water only. Plants were irrigated regularly with tap water during the course of study. The selected levels were used on the basis of lead (2-3 mg Kg -1 soil at -9 cm depth) and chromium (2-4 mg Kg -1 soil at -9 cm depth) content reported in Pakistani soils irrigated regularly by metal contaminated water in the vicinities of large cities like Faisalabad (Ensink et al., 22; UNIDO 22; van der Hoek et al., 22; Ensink et al., 27). The experiment was laid down in a completely randomized design (CRD) with four replicates. The data for relative increase in various growth attributes were started 1 days after treatment for three consecutive 7-day harvest intervals. After each harvest, roots and shoots were separated after harvesting from soil, and shoot and root lengths were measure using a meter rod. The fresh weight of shoots and roots were determined with the help of analytical balance, thereafter plants were oven dried at 7 o C to a constant dry weight and data for dry weights were recorded. The chlorophyll (Chl. a, b and total) contents were determined at third-harvest following the method of Arnon (1949). A.5 g fresh leaf sample was chopped into small pieces and extracted with 8% acetone. The absorbance was read at 645 nm and 663 nm using spectrophotometer (Hitachi, U-21, Japan) and total amount of chlorophyll a, b and total chlorophyll were calculated. At maturity, data for number of pods per plant, seeds per pod, 1-seeds weight and yield per plant were recorded. Statistical analysis: Analysis of variance (ANOVA) of the data was computed using a STATISTICA package for windows, Kernel Release 5.5A (StatSoft, Inc, Tulsa, OK 7414, USA). The Visual General Linear Model (GLM) was fitted using the same statistical package for assessing variation within treatments and interaction terms by splitting their degree of freedom into contrast comparisons.

3 METAL TOXICITY IN MASH BEAN 1391 Results Application of metals in the rooting medium significantly reduced all growth attributes of both mash bean cultivars. The growth rate of both cultivars was found to be maximum at first interval thereafter decreased consistently. Metal stress reduced the growth rate of both cultivars as well. However, both levels of chromium were more toxic as compared to that of lead. Furthermore, highest level of both Cr and Pb maximally reduced the plant growth attributes. Moreover, this adverse effect of both metals was less on growth of FS-1 than that of Mash-97 (Fig. 1, 2 &3). All photosynthetic pigments were drastically reduced by both metal treatments. Analysis of variance of the data for chlorophyll a, b and total chlorophyll contents revealed highly significant differences for genotypes and treatments. However genotype x treatment interaction differed non-significantly. Genotype FS-1 had higher photosynthetic pigments as compared to Mash-97 under both metal stresses. Overall, Fig. 5: Yield attributes of two mashbean cultivars when 14-day old plants were exposed to Pb or Cr in the root medium. Table 1. Analyses of variance (ANOVA) and contrast comparisons for photosynthetic pigments of two mash bean genotypes under lead and chromium stresses. General effect d.f. Chl a Chl b Total Chl Intercept *** 14.9 *** *** Genotypes (G) ***.224 ***.513 *** Treatment (T) 4.38 ***.186 **.313 *** C vs All ***.322 ***.777 *** C vs Pb ***.132 **.414 *** C vs Cr ***.452 ***.932 *** Pb vs Cr ***.143 ***.155 ** V 1 C vs V 1 Pb **.6 **.16 * V 1 C vs V 1 Cr 1.47 ***.26 ***.555 *** V 2 C vs V 2 Pb ***.73 ***.26 ** V 2 C vs V 2 Cr ***.194 **.385 *** V 1 Pb 1 vs V 1 Pb *.97 **.146 * V 1 Cr 1 vs V 1 Cr **.54 *.63 * V 2 Pb 1 vs V 2 Pb *.45 *.54 * V 2 Cr 1 vs V 2 Cr **.64 *.68 * G x T interaction 4.4 ns.3 ns.13 ns V 1 Pb vs V 2 Pb 1.93 **.122 **.354 *** V 1 Cr vs V 2 Cr ***.55 **.94 * V 1 Pb vs V 2 Cr 1.49 *** 314 ***.533 *** V 1 Cr vs V 2 Pb 1.2 ns.6 ns.3 ns Error *, **, ** = significant at.5,.1 and.1 levels, respectively. ns = non-significant, V 1 = FS-1, V 2 = Mash- 97, C = Control, Pb 1 = Lead nitrate (2 mg/l), Pb 2 = Lead nitrate (4 mg/l), Cr 1 = Chromium chloride (2 mg/l), Cr 2 = Chromium chloride (4 mg/l), The 4 degree of freedom have been split into contrasts to check the variation within treatments (T) or variety x treatment (V x T) interaction.

4 1392 HUSSAIN ET AL. Relative decrease in shoot length (cm/day) (a) Interval 1 Interval 2 Interval FS-1 Mash-97 FS-1 Mash-97 Relative decrease in root length (cm/day) (b) FS-1 Mash-97 FS-1 Mash-97 Fig. 1. Relative decrease in shoot and root lengths of two mashbean cultivars when 14- day old plants were exposed to Pb or Cr in the root medium. Relative decrease in shoot f. wt. (g/ day) (a) Interval 1 Interval 2 Interval FS-1 Mash-97 FS-1 Mash-97 Relative decrease in root f. wt. (g/ day) (b) FS-1 Mash-97 FS-1 Mash-97 Fig. 2. Relative decrease in shoot and root fresh weights of two mashbean cultivars when 14-day old plants were exposed to Pb or Cr in the root medium.

5 METAL TOXICITY IN MASH BEAN 1393 Relative increase in shoot d. wt. (g/day) (a) Interval 1 Interval 2 Interval FS-1 Mash-97 FS-1 Mash-97 Relative increase in root d. wt. (g/day) (b) FS-1 Mash-97 FS-1 Mash-97 Fig. 3. Relative decrease in shoot and root dry weights of two mash bean cultivars when 14-day old plants were exposed to Pb or Cr in the root medium. FS-1 Mash-97 2 (a) LSD (5%) = ns 1.6 (b) LSD (5%) = ns Chl a (mg/g) Chl b (mg/g) (c) LSD (5%) = ns 3 (d) Total Chl (mg/g) Chl a /b ratio Fig. 4. Photosynthetic pigments of two mash bean cultivars when 14-day old plants were exposed to Pb or Cr in the root medium.

6 1394 HUSSAIN ET AL. Table 2. Analyses of variance (ANOVA) and contrast comparisons for yield attributes of two mash bean genotypes under lead and chromium stresses. General effect d.f. Pods/plant Seeds/pod Yield/plant 1 seed weight Intercept *** *** 6.14 *** 3.55 *** Genotypes (G) *** 3.2 *.23 ***.123 *** Treatment (T) *** 8.18 ***.27 ***.85 *** C vs All *** 18.9 ***.51 ***.194 *** C vs Pb *** 1.2 ***.34 ***.12 *** C vs Cr *** ***.61 ***.29 *** Pb vs Cr 1.78ns 2.53 *.7 **.18 * V 1 C vs V 1 Pb * 4.16 *.12 ***.65 ** V 1 C vs V 1 Cr 1 6. ** 12.4 ***.56 ***.16 ** V 2 C vs V 2 Pb ** 7.4 **.2 ***.55 ** V 2 C vs V 2 Cr ** 9.37 ***.25 ***.13 *** V 1 Pb 1 vs V 1 Pb * 2. *.14 ***.49 ** V 1 Cr 1 vs V 1 Cr * 3.12 *.5 *.1 * V 2 Pb 1 vs V 2 Pb * 3.13 *.6*.15 * V 2 Cr 1 vs V 2 Cr * 3.13 *.5 *.68 *** G x T interaction 4.21 ns.21 ns.1 ns.4 ns V 1 Pb vs V 2 Pb ** 3.6 *.15 ***.44 ** V 1 Cr vs V 2 Cr 1 1. ns.25 ns.2 *.52 ** V 1 Pb vs V 2 Cr ** 5.6 **.2 ***.99 *** V 1 Cr vs V 2 Pb 1 1. ns.1 ns. ns.15 * Error *, **, ** = significant at.5,.1 and.1 levels, respectively. ns = non-significant, V 1 = FS-1, V 2 = Mash- 97, C = Control, Pb 1 = Lead nitrate (2 mg/l), Pb 2 = Lead nitrate (4 mg/l), Cr 1 = Chromium chloride (2 mg/l), Cr 2 = Chromium chloride (4 mg/l), The 4 degree of freedom have been split into contrasts to check the variation within treatments (T) or variety x treatment (V x T) interaction. FS-1 Mash-97 5 (a) LSD (5%) = ns 7 (b) LSD (5%) = ns Number of pods/plant Number of seeds/pod (c) LSD (5%) = ns 1 (d) LSD (5%) =.25 Seed yield/plant (g) seed weight (g) a a b b a cd a -6.1 c c c d d Fig. 5. Yield attributes of two mash bean cultivars when 14-day old plants were exposed to Pb or Cr in the root medium.

7 METAL TOXICITY IN MASH BEAN 1395 Discussion In this study, metal treatments drastically reduced growth of both mash bean cultivars. It was observed that both metals were more toxic at higher levels as compared to their lower ones. This decrease in growth might be attributed to decrease in photosynthetic pigments that were drastically reduced in this study (Sharma & Sharma, 23) that lead to decreased photosynthesis and hence decreases supply of photosynthesis products to the actively growing organs that suppressed growth (Fargašová, 1998). Moreover disturbance in nutrient uptake and metabolism as a result of increased metal content in the growth environment (data not reported) might explain this reduction in growth (Panda & Choudhary, 25). Chlorophyll a, b and total chlorophyll were drastically reduced under both metal treatments especially at higher level. In this study, severe chlorosis on older leaves and scarce appearance on younger leaves suggested that decline in chlorophyll content in shoots of metal treated plants result mostly from its enhanced degradation or reduced synthesis (Stobart et al., 1985; Somashekaraiah et al., 1992). Moreover, chlorophyll a/b ratio was not affected under metal treatments (Figure 4). This suggested that both chlorophyll a and b were equally sensitive to metal stress in both mash bean cultivars (Gajewska et al., 26). All yield parameters were drastically reduced under both metal stresses. This reduction in yield might be due to decreased photosynthesis as a consequence of reduction in photosynthetic pigments under both metal stresses (Fargašová, 1998). In addition, decrease vegetative growth under metal stress lead to suppressed reproductive growth (Arun et al., 25). Moreover, flower and pod senescence as a consequence of metal toxicity lead to production of less number of viable pods and seeds that reduced yield under metal stress (Sharma & Dubey, 25). Overall, highly toxic effects of chromium and lead metals on growth, photosynthetic pigments and yield components in mash bean were observed in this study. Moreover, mash bean cultivar FS-1 proved to be more tolerant as compared to Mash-97. References Arun, K.S., C. Cervantes, H. Loza-Tavera and S. Avudainayagam. 25. Chromium toxicity in plants. Environ. Int., 31: Baccouch, S.A.C. and E. El Ferjani Nickel-induced oxidative damage and antioxidant responses in Zea mays shoots. Plant Physiol. Biochem., 36: Chaney, R.L. and J.A. Ryan Risk Based Standards for Arsenic Lead and Cadmium in Urban Soils. Dechema, Frankfurt, Germany. 11: 163. de Abreu, C.A., M.F. de Abreu and J.C. de Andrade Distribution of lead in the soil profile evaluated by DTPA and Mehlich-3 solutions. Bragantia, 57: Ensink, J.H.J., R.W. Simmons and W. van der Hoek. 27. Wastewater Use in Pakistan: The Cases of Haroonabad and Faisalabad. The International Development Research Centre, Canada. Ensink, J.H.J., W. van der Hoek, Y. Matsuno, S. Munir and M.R. Aslam. 22. The use of untreated wastewater in peri-urban agriculture in Pakistan: Risks and opportunities. IWMI Research Report no. 64, International Water Management Institute, Colombo, Sri Lanka. Fargašová, A Root growth inhibition, photosynthetic pigments production, and metal accumulation in Synapis alba as the parameters for trace metals effect determination. - Bull. Environ. Contam. Toxicol., 61:

8 1396 HUSSAIN ET AL. Gajewska, E., M. Skłodowska, M. Laba and J. Mazur. 26. Effect of nickel on antioxidative enzyme activities, proline and chlorophyll contents in wheat shoots. Biol. Plant., 5 (4): James, A.D Legumes in United States. Department of Agriculture, Beltsville, Maryland Plenum press New York. Panda, S.K. and S. Choudhary. 25. Chromium stress in plants. Braz. J. Plant Physiol., 17(1): Shanker, A.K., C. Cervantes., H.L. Tavera and S. Avudainayagam. 25. Chromium toxicity in plants. J. Environ. Int. 31: Sharma, D.C and C.P. Sharma. 23. Chromium uptake and toxicity effects on growth and metabolic activities in wheat, Triticum aestivum. Indian. J. Exp. Biol., 34: Sharma, P. and R.S. Dubey. 25. Lead toxicity in plants. Braz. J. Plant Physiol., 17(1): Somashekaraiah, B.V., K. Padmaja and A.R.K. Prasad Phytotoxicity of cadmium ions on germinating seedlings of mungbean (Phaseolus vulgaris): Involvement of lipid peroxides in chlorophyll degradation. Physiol. Plant., 85: Stobart, A.K., W.T. Griffiths, I. Ameen-Bukhari and R.P. Sherwood The effect of Cd 2+ on the biosynthesis of chlorophyll in leaves of barley. Physiol. Plant., 63: UNIDO. 22. Industrial Policy and the Environment in Pakistan (NC/PAK/97/18), United Nations Industrial Development Organization (UNIDO), 11 December 2. van der Hoek, W., M.U. Hassan, J.H.J. Ensink, S. Feenstra, L. Raschid-Sally, S. Munir, R. Aslam, N. Ali, R. Hussain and Y. Matsuno. 22. Urban Wastewater: A valuable resource for agriculture - A case study from Haroonabad, Pakistan. IWMI Research Report no. 63, International Water Management Institute, Colombo, Sri Lanka, pp: 14. Yang, Y.Y., J.Y. Jung., W.Y. Song., H.S. Suh and Y. Lee. 2. Identification of rice varieties with high tolerance or sensitivity to lead and characterization of the mechanism of tolerance. Plant Physiol., 124: (Received for publication 18 September, 26)

9 1769 PAKISTAN BOTANICAL SOCIETY OFFICERS AND COUNCIL FOR 26 President Dr. M. Ashraf Department of Botany, University of Agriculture, Faisalabad. Vice-President Dr. S.M. Saqlain Naqvi Department of Biochemistry, University of Arid Agriculture, Rawalpindi. Dr. Muhammad Tahir Rajput Department of Botany, University of Sindh, Jamshoro. Dr. Mufakhira Jan Durrani Department of Botany, University of Balochistan, Quetta. Dr. Farrukh Hussain Department of Botany, University of Peshawar, Peshawar. Mr. Shafiq-ur-Rehman Department of Botany, University of AJ&K Muzaffarabad. Secretary/Treasurer Dr. M. Yasin Ashraf NIAB, Faisalabad. Joint Secretary Dr. Syeda Saleha Hassney Department of Botany, University of Sindh, Jamshoro. Chief Editor Dr. Abdul Ghaffar, Department of Botany, University of Karachi. COUNCIL The Officers of the Pakistan Botanical Society, the President and Secretary ex officio, Prof. Nuzhat Parveen, Shipowners College, Karachi; Dr. A. Qayyum Soomro, University of Sindh, Jamshoro; Dr. Shahida Hasnain, University of the Punjab, Lahore; Dr. Manzoor H. Soomro, PSF, Islamabad; Dr. Fazle Malik Sarim, University of Peshawar; Dr. A. Razzak Mahar, Shah Abdul Latif University, Khairpur; Dr. Tayyab Hussain Bukhari, Govt. College, Toba Tek Singh.

10 Vol. 38(5): Special Issue Contents December, 26 Page Muhammad Ashraf and Habib-ur-Rehman Athar - Preface 1357 Sayed Anwar-ul-Haque - Salinity problems and crop production in coastal 1359 regions of Bangladesh - Review Article Abdallah Atia, Ahmed Debez, Mokded Rabhi, Habib-ur-Rehman Athar, 1367 and Chedly Abdelly - Alleviation of salt-induced seed dormancy in the perennial halophyte Crithmum maritimum L. (Apiaceae) Shahid Umar - Alleviating adverse effects of water stress on yield of sorghum, 1373 mustard and groundnut by potassium application M.U. Shirazi, M.A. Khan, Mukhtiar Ali, S. M. Mujtaba, S. Mumtaz, 1381 Muhammad Ali, B. Khanzada, M.A. Halo, M. Rafique, J. A. Shah, K.A. Jafri, and N. Depar - Growth performance and nutrient contents of some salt tolerant multipurpose tree species growing under saline environment Mumtaz Hussain, Muhammad Sajid Aqeel Ahmad and Abida Kausar Effect of lead and chromium on growth, photosynthetic pigments and yield components in mash bean [Vigna mungo (L.) Hepper] Bechir Ben-Rouina, Chedlia Ben Ahmed, Habib-ur-Rehman Athar, and M Boukhriss - Water relations, proline accumulation and photosynthetic activity in olive tree (Olea europaea L. cv Chemlali ) in response to salt stress Ameer Khan, Muhammad Sajid Aqeel Ahmad, Habib-ur-Rehman Athar 147 and Muhammad Ashraf - Interactive effect of foliar applied ascorbic acid and salt stress on wheat (Triticum aestivum L.) at seedling stage A. R. Gurmani, A. Bano and Muhammad Salim - Effect of growth regulators 1415 on growth, yield and ions accumulation of rice (Oryza sativa L.) under salt stress Muhammad Asif, Mehboob-ur-Rahman and Yusuf Zafar - Genotyping 1425 analysis of six maize (Zea mays L.) hybrids using DNA fingerprinting technology Sezgin Celik - Studies on the germination of three endangered Centurea species 1431 Vishandas, Zia-ul-Hassan, Muhammad Arshad and Ahmad Naqi Shah Phosphorus fertigation at first irrigation due to its unavailability at sowing time prevents yield losses in Triticum aestivum L. M. Kashif Shahzad Sarwar, Ihsan Ullah, Mehboob-ur-Rahman, M. Yasin 1449 Ashraf and Yusuf Zafar - Glycinebetaine accumulation and its relation to yield and yield components in cotton genotypes grown under water deficit condition Muhammad Sajid Aqeel Ahmad, Qasim Ali, Rohina Bashir, Farrukh Javed 1457 And Ambreen Khadija Alvi - Time course changes in ionic composition and total soluble carbohydrates in two barley cultivars at seedling stage under salt stress Tayyaba Shaheen, Mehboob-ur-Rahman and Yusuf Zafar - Chloroplast rps gene of cotton reveals the conserved nature through out plant taxa Chedlia Ben-Ahmed, B. Ben-Rouina, Habib-ur-Rehman Athar, M Boukhriss - Olive tree (Olea europaea L. cv. Chemlali ) under salt stress: water relations and ions content Jim Morris, John Collopy and Khalid Mahmood - Canopy conductance and 1485 water use in Eucalyptus plantations B. Shaharoona, Riffat Bibi, Muhammad Arshad, Zahir Ahmed Zahir, and Ziaul-Hassan Aminocylopropane-1-carboxylate (ACC)-deaminase rhizobacteria extenuates ACC-induced classical triple response in etiolated pea seedlings Roubina Kauser, Habib-ur-Rehman Athar, and Muhammad Ashraf Chlorophyll fluorescence can be used as a potential indicator for rapid assessment of water stress tolerance in canola (Brassica napus L.) Cont d. inside back cover

11 Uzma Farooq and Asghari Bano - Effect of abscisic acid and chlorocholine chloride on nodulation and biochemical content of Vigna radiata L. under water stress Ruya Yilmaz, Serdal Sakcali, Celal Yarci, Ahmet Aksoy and Munir Ozturk - Use of Aesculus hippocastanum L. as a biomonitor of heavy metal pollution. Tariq Aziz, Rahmatullah, Muhammad Aamer Maqsood, Mukkram. A. Tahir, Iftikhar Ahmad and Mumtaz A. Cheema - Phosphorus utilization by six Brassica cultivars (Brassica juncea L.) from tri-calcium phosphate; a relatively insoluble P compound Gul Sanat Shah Khattak, Iqbal Saeed And Tila Muhammad - Breeding for heat tolerance in mungbean (Vigna radiata (L.) Wilczek) Nazila Azhar, M. Yasin Ashraf, M. Hussain and F. Hussain - Phytoextraction of lead (Pb) by EDTA application through sunflower (Helianthus annuus L.) cultivation: Seedling growth studies. Muhammad Ibrahim, Ambreen Anjum, Nabeela Khaliq, Muhammad Iqbal and Habib-ur-Rehman Athar - Four foliar applications of glycinebetaine did not alleviate adverse effects of salt stress on growth of sunflower Muhammad Aslam, Iftikhar A. Khan, Muhammad Saleem and Zulfiqar Ali - Assessment of water stress tolerance in different maize accessions at germination and at early growth stage Nudrat Aisha Akram, Muhammad Shahbaz, Habib-ur-Rehman Athar, and Muhammad Ashraf - Morpho-physiological responses of two differently adapted populations of Cynodon dactylon (L.) Pers. and Cenchrus ciliaris L. to salt stress M. Yasin Ashraf, Kalsoom Akhter, F. Hussain and Javed Iqbal - Screening of different accessions of three potential grass species from Cholistan desert for salt tolerance Nabila Tabbasam, Mehboob-ur-Rahman and Yusuf Zafar - DNA-based genotyping of sorghum hybrids Abdul Hameed, Muhammad Zaheer Ahmed and Muhammad Ajmal Khan - Comparative effects of NaCl and seasalt on seed germination of coastal halophytes Tanwir Ahmad Malik, Sana-Ullah, and Samina Malik - Genetic linkage studies of drought tolerant and agronomic traits in cotton Qasim Ali, Habib-ur-Rehman Athar and Muhammad Ashraf - Influence of exogenously applied brassinosteroids on the mineral nutrient status of two wheat cultivars grown under saline conditions M. A. Khan, M.U. Shirazi, Mukhtiar Ali, S. Mumtaz, A. Sherin, and M. Y. Ashraf - Comparative performance of some wheat genotypes growing under saline water Naeem Iqbal and Muhammad Yasin Ashraf - Does seed treatment with glycinebetaine improve germination rate and seedling growth of sunflower (Helianthus annuus L.) under osmotic stress Irfan Afzal, Shahzad Maqsood Ahmad Basra, Amjad Hameed and Muhammad Farooq - Physiological enhancements for alleviation of salt stress in wheat Muhammad Saeed Akram, Qasim Ali, Habib-ur-Rehman Athar and Ahmed Saeed Bhatti - Ion uptake and distribution in Panicum antidotale Retz. under salt stress Sulman Shafeeq, Mehboob-ur-Rahman and Yusuf Zafar - Genetic variability of different wheat (Triticum aestivum L.) genotypes/cultivars under induced water stress

12 Cont d. on page 177 Ihsan Ullah, Mehboob-ur-Rahman and Yusuf Zafar - Genotypic variation for 1679 drought tolerance in cotton (Gossypium hirsutum L.): seed cotton yield responses Ismat Nawaz, Zia-Ul-Hassan, Atta Muhammad Ranjha and Muhammad 1689 Arshad - Exploiting genotypic variation among fifteen maize genotypes of Pakistan for potassium uptake and use efficiency in solution culture Munir Ahmad, Zahid Akram, Muhammad Munir and Muhammad Rauf Physio-morphic response of wheat genotypes under rainfed conditions Qasim Ali, Habib-ur-Rehman Athar and Muhammad Ashraf - Ion transport 173 in four canola cultivars as influenced by salt stress S.F. Afzali, M.A. Hajabbasi, H. Shariatmadari, K. Razmjoo, and A.H. 179 Khoshgoftarmanesh - Comparative adverse effects of PEG- or NaCl-induced osmotic stress on germination and early seedling growth of a potential medicinal plant Matricaria chamomilla Mukkram Ali Tahir, Rahmatullah, Tariq Aziz, M.Ashraf, Shamsa Kanwal 1715 and Muhammad Aamer Maqsood - Beneficial effects of silicon in wheat (Triticum aestivum L.) under salinity stress Shamyla Nawazish, Mansoor Hameed and Shaista Naurin - Leaf anatomical 1723 adaptations of Cenchrus ciliaris l. from the salt range, Pakistan against drought stress Farah Naz, Shafqat Farooq, Rubina Arshad, Muhammad Afzaal and 1731 Muhammad Akram - Discriminating upland and lowland rice genotypes through proteomic approach Muhammad Akram, Shafqat Farooq, Muhammad Afzaal, Farah Naz, and 1739 Rubina Arshad - Chlorophyll fluorescence in different wheat genotypes grown under salt stress Muhammad Afzaal, Shafqat Farooq, Muhammad Akram, Farah. Naz, 1745 Rubina Arshad and Asghari Bano - Differences in agronomic and physiological performance of various wheat genotypes grown under saline conditions Rubina Arshad, Shafqat Farooq and Farooq-E-Azam - Rhizospheric bacterial 1751 diversity: Is it partly responsible for water deficiency tolerance in wheat? Shamaila Rafiq, Tahira Iqbal, Amjad Hameed, Zulfiqar Ali Rafiqi and 1759 Naila Rafiq - Morphobiochemical analysis of salinity stress response of wheat Published by the Pakistan Botanical Society. Printed at Karachi University Press, Karachi-7527, Pakistan. Phone: , Copies available from the Chief Editor, Pakistan Journal of Botany, Department of Botany, University of Karachi, Karachi-7527, Pakistan. Phone: Price: Each issue Rs. 1/ US$2; Vol. Rs. 6/US$12 or in exchange.