RESPONSE OF RICE TO VARIOUS SOURCES OF NITROGEN IN A SALT-AFFECTED SOIL

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1 Pak. J. Agri. SeL, Vl. 30, N.1, 1993 RESPONSE OF RICE TO VARIOUS SOURCES OF NITROGEN IN A SALT-AFFECTED SOIL Imdad Ali Mahmd, R.H. Qureshi, M. Aslam, S. Nawaz & B. Akhtar Department f Sil Science, University f Agriculture, Faisalabad The efficiency f different N fertilizers and their mixture under tw salinity levels i.e. cntrl (EC c = 1.7 ds ml) and EC. = 10 ds m-t was cmpared by recrding the number f tillers, straw and paddy yields f rice variety KS 282. Nitrgen was 60 and 80 mg kg-t f sil as urea, ammnium sulphate and a mixture f urea + ammnium sulphate in 1:1 rati. Significant reductin in number f tillers and straw, paddy yields was bserved due t salinity. Nitrgen applicatin increased N cncentratin, N uptake and decreased K+, Na + and cr cncentratin in straw and paddy. Nevertheless, applicatin f N in the frm f ammnium sulphate r its mixture with urea in 1:1 rati prduced statistically better yields than the straight N applicatin as urea. At lwer dse, the mixture was fund as efficient as the high dse f straight fertilizers. INTRODUCTION Ecnmic use f salt-affected sils requires reclamatin thrugh leaching f salts and use f amendments like gypsum and sulphur, etc. But n accunt f certain limitatins, such as insufficient supply f canal water, lw sil permeability, use f brackish grundwater, etc., these practices are nt fully applicable'. This has led t suggestins fr the use f essential plant nutrients, including N, n mderately saltaffected sils fr establishing ecnmical farming. Under saline and sdic sil cnditins, the N requirement fr ptimum yields might increase because adverse sil cnditins mdify the nature and extent f N transfrmatin (Bhardwaj and Abrl, 1976). Biswas et ai (1985) advcated that crps grwn n sdic sils require 14-20% mre N cmpared t that fr nrmal sils. Under high salinity, grwth and yield f rice is drastically reduced but with prper sil and fertilizers management, it can give better prductin (Aslam et al. 1989). The present investigatin was, therefre, undertaken t assess the perfrmance f rice and relative efficiency f different N surces under tw salinity levels. MATERIALS AND METHODS The experiment was cnducted in glazed pts having 30 cm diameter. Each pt was filled with 10 kg f nn-saline sandy clay lam sil having ph 7.9, EC c 1.7 ds mt, ttal N 0.06% and CEC 7.9 me 100 gt. There were tw salinity levels, ne cntrl (EC c = 1.7 ds mt) and the ther f EC c 10 ds Salinity level f EC c 10 ds m- t was impsed artificially using apprpriate amunts f NaCI. The varius surces f N and their dses were as under: T Cntrl (N nitrgen) T) 60 mg N l as urea T 1 80 mg N kg-t as urea T 3 60 mg N kg-t as ammnium sulphate T 4 80 mg N kg- l as ammnium sulphate 64

2 Pak. J. Agri. Sci., Vl. 30, N.1, J993 T, 60mg N kg! as urea + ammnium sulphate (1:1) T 6 80 mg N kg-i as urea + ammnium sulphate (1:1) Half f the N dse was applied at the time f seedling transplanting and the remaining half was tp dressed 45 days after transplanting. A basal dse f P, K and 40, 25 and 5 mg kg-i as SSP, SOP and ZnS04, respectively was applied in all the pts including cntrl at the time f seedling transplanting. Canal water was applied thrughut the grwth perid f the crp. Tillering was recrded at panicle initiatin and plant samples were cllected fr chemical analysis. The crp was harvested at maturity fr recrding the paddy and straw yields. Dried and grund plant material was analysed fr N, K +, Na + and cr cncentratins. Data were analysed statistically by ANOVA technique fllwing Cmpletely Randmized Design (Steel and Trrie, 1980). RESULTS AND DISCUSSION Number f tillers: On the average reductin f 33% in tillers was bserved with the salt treatment (Table 1). Nevertheless, with the applicatin f N, the number f tillers increased even at high salinity and was the highest in T4 and T 6 Similar results have been presented by Pearsn et al. (1966). Straw and paddy yield: The use f N fertilizers under bth nn-saline and saline cnditins increased yield significantly (Table 1). Maximum average straw yield was prduced by T 6 fllwed by T4 and T2 Abut 94 t 141% increase in yield was bserved with varius fertilizer treatments ver the cntrl. Similar results were reprted by Verma and Neue (1984). The average paddy yield was reduced by abut 67% at EC. 10 ds ml as cmpared t that frm the nrmal sil. There were number f reasns as t why yield decreases under saline cnditins (Aslam et al., 1991). Maximum paddy yield was prduced by T 6 amng all the treatments. The yield with T4 and T 2 were similar fllwed by T, and T J The yields f Ts, TJ and T) were significantly better cmpared t that frm the cntrl. Thus the use f mixture f urea + ammnium sulphate 80 mg N kg-i than straight applicatin f ammnium sulphate r urea was fund t be superir. The reasn may be the minimum lsses f N frm mixture applicatin. Zia (1969) and Biswas (1987) als fund similar results. Frm the data, it is clear that reductin in paddy yield due t salinity was severe as cmpared t tillering and straw yield indicating that vegetative phase is less affected by salt stress than the reprductive phase. Similar cnclusins were drawn by Akbar (1985) and Aslam et al. (1988). Chemical cmpsitin f rice straw and paddy Nitrgen: The data indicated that treatments T 6, T4 and T 2 were statistically similar cmpared t the rest f the treatments (Table 2). Minimum N cncentratin was recrded in cntrl plants. In the fertilizer treatments, increase in N cncentratin was bviusly due t the better supply f this nutrient in sil assciated with relatively higher uptake by plants. This increase in N cncentratin at higher salinity may be attributed t reductin in dry matter Yield. Maximum N uptake was 80 mg N kg- l as ammnium sulphate r mixture f urea + ammnium sulphate. Less uptake f N in case f urea' than ammnium sulphate r mixture f urea + ammnium sulphate culd be due t vlatilizatin lsses f urea under saline envirnment (Hamid and Ahmed, 1988). 65

3 Pak. J. Agri. sa; Vl. 30, N.1, 1993 Jf U.Cll.. l; 0 _ 1 :g... s:,. &. b bo III.,;... 0 t &. t zis U.i..gN Vi aq "t 'O:t; ti'l-f''c... t-... z ClI:. z, ;; '00 a:... Z.. «tj++ z«:j:j :a ilifife'eeif 8.,:.'..:.:'..: 66

4 Pak. J. Agri. sa; Vl. 30, N.1, 1993 'C :..' u 'C....5 c.2 c 8ȯ "" :; + :;. + c :5 -= ""c :s!!l... ';: l&i z..... z lli:: C'S"OlUtlU.Du,;; :;;...c tli»._. -s ;J;::j " c..,. bi) "- "_ 00 Vi ;::. Ptassium: Maximum K + cncentratin was fund in cntrl plants which was significantly superir t all the ther fertilizer treatments (Table 2). There was maximum K + cncentratin in plant grwn at EC. 1.7 ds ml and it decreased by abut 29% with increase in salt stress in the rting medium. Lw cncentratin f K + in T4 may be attributed t the grwth dilutin effect. Decrease in K + cncentratin with salinity may be related t an increase in the uptake f Na + as against K + frm the rting medium having high Na:K rati (Aslam et al., 1992). Sdium: Maximum Na" cncentratin was fund in the cntrl plants. The data (Table 3) shwed that increasing rate f N further lwered the cncentratin f Na + in plants. With salinity, the Na + cncentratin f plants increased by apprximately 40% f that ld nrmal sil. The results are ld agreement t thse reprted by Kaddah et al. (1975) and Aslam et al. (1992). Chlride: Maximum cr cncentratin was fund in cntrl plants while increasing the rate f N decreased it. The minimum cncentratin f this in was fund in the case f T 4 may be due t mre and rapid grwth resulting in less accumulatin f this in in plant tissues. Sil salinity has a psitive and highly significant relatinship with the cr cncentratin. The data n cr cncentratin fllwed the same trend as that f Na" (Table 3) i.e., the cncentratin increased with the increasing level f sil salinity while N material and its rates bad depressive effect n the cr cncentratin in plant tissues. Kaddah et al. (1975) and Aslam et al. (1992) have dcumented results. similar 67

5 Pak. J. Agri. Sci., Vl. 30, N. I, /993 REFERENCES Akbar, M., T. Yabun and S. Naka Breeding fr saline resistant varieties f rice. J. Variability fr salt tlerance amng sme rice varieties. Japan J. Breed. 22: 277-2f34. Aslam, M., A Rauf, N. Ahmed, J. Akhtar and R.H. Qureshi Nitrgen management fr rice in a salt-affected sil. Pak. J. Agri. Sci. 29: Aslam, M., R.H. Qureshi, N. Ahmad and S. Muhammed Respnse f rice t salinity shcks at varius grwth stages and types f salinity in the rting medium. Pak. J. Agri. Sci. 25: Aslam, M., RH. Qureshi, N. Ahmad and M.A Kausar Relative grwth rati and in transprt in rice under saline cnditins. Pak. J. Bt. 23: Aslam, M., R.H. Qureshi, T. Masd and R. Ahmad Yield and quality f maize fdder as influenced by nitrgen fertilizers in saline sil. Pak..I. Sil Sci. 4: 5-9. Bhardwaj, K.K.R. and J.P. Abrl Nitrgen management in alkali sils. In: Prc. Natl. Symp. Nitrgen Assimilatin and Crp Prductivity. Oct., 1976, Hissar, India. Biswas, C.R N, P and K uptake f rice n castal saline sils.irrn. 12: 42. Biswas, B.S., D.S. Yadav and S. Maheshwari Management in saltaffected and acid sils. Fert. News, 30: 2f3-33. Hamid, A and M. Ahmed Suppressin f ammnia vlatilizatin frm urea thrugh fertilizer mdificatins: J. Effect f ammnia salts. Pak. J. Agri. Sci. 24: Kaddah, M.T., W.F. Lehman, B.D. Meek and F.E. Rbinsn Salinity effects n rice after the bt stage. Agrn. J. 63: Pearsn, G.A, AD. Ayers and D.L. Ederherd, Relative salt tlerance f rice during germinatin and early seedling develpment. Sil Sci. 102: Steel, R.G.D. and J.H. Trrie Principles and Prcedures f Statistics. Me- Graw Hill Bk C. Inc., NY, USA Verma, T.S. and H.U. Neue Effect f sil salinity level and zinc applicatiun n grwth, yield and nutrient cmpsitin f rice. Plant Sil, 82: Zia, M.S Nitrgen uptake by IRRI rice as affected by salinity and varius surces f nitrgen. M.Sc. Thesis, Dept. Sil Sci., West Pak. Agri. Univ., Lyallpur (UAF). 68