B. A. ZAYED et

African Crop Science Conference Proceedings Vol. 8. pp. 53-60Printed in El-Minia, EgyptISSN 1023-070X/2007$ 4.00© 2007, African Crop Science Society

Role of potassium application on the productivity of some inbred and hybrid rice varieties under newly reclaimed saline soils

B. A. ZAYED, W. M. ELKHOBY, S.M.SHEHATA & M. H. AMMARRice Research and training center, Sakha, Kafr El- Sheikh, Field Crop Research Institute, ARC. Egypt.,

E-mail:basunyz@yahoo.com

Abstract: Two field experiments were conducted at the experimental farm of El Sirw Agriculture Research Dammiattaprefecture, Egypt during 2005 and 2006 seasons. The study aimed to investigatethe effect of various potassium rates; Zero, 24, 48 and 72 Kg K2O /ha, ongrowth, sodium, potassium leaf content and their ratio at heading, grain yieldand yield components of three hybrids: SK2034H, SK2046H and SK2058H and threevarieties; Giza 177, Giza 178 and Sakha 104. The economic values were alsoestimated. The experimental soil was clayey with salinity levels of 8.5 and8.7 dS/m in the first and second seasons, respectively. The experiments wereperformed in a split plot design with four replications. The main plots weredevoted to the tested rice varieties, while potassium rates were distributed inthe sub plots. The studied varieties varied significantly in their growthparameters, Na+ and K+ leaf content at heading as well as ratio, yieldcomponents and their economic values. SK2034H surpassed the restvarieties without any significant differences with SK2046H. SK2058Hdidn’t show advantage over Giza 178 or Sakha 104. Giza 177 was the worstunder such conditions. Increasing potassium rate significantly improved allstudied traits leading to high grain yield. Furthermore, potassium succeededto reduce Na+, lower Na+ /K+ ratio and raised K+ resulted in considerablesalinity withstanding. The hybrids of SK2034H and SK2046H as well as the saltsensitive rice variety Giza 177 were the most responsive genotypes forpotassium fertilizer up to 72 kg K2O /ha. Consequently, the economic estimatesSK2034H hadthe higher net return and the high potassium level of 72 kg k2o /ha gave the highest values of economic parametersunder the tested saline soil conditions.

Introduction

Salinity is a stress to which rice isrelatively sensitive. In Egypt,Salinity limited rice productionunder wide spectrum area, saltdamage to rice seedling as a result ofexcessive transport of those ionscausing the salinity (Commonly, butnot exclusively, sodium and chloride)to the leaves (Garcia et al., 1997).Potassium has essential functions

in osmoregulation, enzymeactivation, regulation of

clever pH, Cation- anion balance,

regulation of transpiration bystomata, and the transportof assimilates and subsequentlyraised rice tolerance forsalinity. (Lee & Senadhira (1996)and Zayed et al., 2002) found thatincreasing the K uptake abilityunder stress enable rice plant togrow healthy under salt stress.

Varietals differences in their growth, Na+, K+, Na/K

ratio, yield and yield components of rice were emphasized by El- Mowafy,(1994), Shehata (1995), Zayed (1997)Zayed (2002) and Abd El- Rahman et al., (2004). Singh,

(2002), patil et al., (2003), Gatuam, (2004), Abou-khalifa(2005) stated that hybrid ricevarieties surpassed inbred ricevarieties in their growth, yield andyield components. In addition, undersaline soil, Zayed et al., (2006). statedthat some hybrid such SK2034H wasfound to be more tolerant for saltand exceeded the Giza 178, Sakha104, Giza 177 and other hybrids intheir growth, yield and yieldcomponents Muhammed and Neue(1987), and Qadar, (1998) referredthat K+ addition to Saline culturesolution markedly improved rice yieldand yield attributes as a results ofincreasing K+ uptake and decreasingNa+ uptake. Sharma et al., (1995),Zayed. (2002), Abd El- Rahman etal., (2004) stated rice plantsignificantly responded to increasingpotassium level up to 75 or 171 kgK2o/ha. Furthermore, increasingpotassium rate

53

increased rice growth, yield and yieldattributes, K+ and lower Na+ uptake andNa+/K+ ratio. Regarding hybrid riceresponse to Potassium fertilizer,Pandy et al., (1993)Kalita et al., (1995), Zhu et al.,(1998) Singh et al., (1999), Dwivedi etal., (2000) and Samrath et al., (2002)reported that hybrid rice is highlyresponsive to Potassium applicationwhereas, increasing Potassium rate upto 150 kg/ha significantlypromoted its growth, all yieldattributing characters and grainyield as well as straw yield.Hybrid rice is highlyfertilizer responsive, particularlyfor potassium, but information onhybrid rice potassium nutrition inEgypt especially under saline soil ismeager. Therefore, adequate Potassiumfertilization at right and proper rateis essential to achieve potentialyield of hybrid rice and enhancerice salt tolerance keeping thesepoints in view, the presentinvestigation was undertaken.

Materials and MethodsTwo field experiments were

conducted at theexperimental farm of Sirw agriculturalResearch Station, Dammietta, Egyptduring the seasons of 2005 &2006. The experimental soil wasclay with pH, 8.1, 8.2, EC.,8.5, 8.7 Na+, 50 & 55, K+0.29 & 0.27meq/l, available K+ ,200 & 180 kg/ha available nitrogen;160 & 140 kg/ha and availablephosphorus; 14 & 13 kg/ha in thefirst and second seasons,respectively. The treatmentscomprisedthe response of three hybrid rice varieties, Viz, SK2034H,SK2046H & SK2058H and three inbred ricevarieties Viz; Giza 177, Giza 178 andSakha 104 to four potassium ratesnamely; 0 , 24 , 48 and 72 Kg K2O/ ha.

The experiment was laid out in a split plot design with

four replications, keeping rice varieties in the main plots

B. A. ZAYED etal.,

and the nitrogen levels in the subplots, with fourreplications. Seedlings of 30 daysof rice varieties were transplantedwith 3 seedlings/hill on May 30th,whereas the sowing was done on April30th. Nitrogen in the form of urea(163 kg N/ha) was imposed in 4 equaldoses 15 days after transplanting(DAT), mid-tillering stage,panicle initiation , and end ofbooting stages associated with eachvariety as recommended under salinesoil and hybrid rice. Potassium inthe form of potassium sulfate wasbasally applied. All plots were given50 kg P2O5 / ha.The plot area was 10 m2. At heading, ten hills from eachplot were taken to estimate the dry mater and leaf area index (LAI). The days from sowing to heading wasestimated. The leaves of five plants were collected to thelaboratory, dried, grounded

and analyzed fordetermination Na+ and K+ and Na+ /K+ratio according to Yoshida et al., (1976).At harvest, panicles of ten hills foreach plot were counted to determinethe panicle numbers/m2 and also, plant height wasmeasured. Ten main panicles fromeach subplot were packed to thelaboratory to determine paniclelength (cm), filled and unfilledgrains/ panicle, and panicle and 1000-grain weights. The plants of thesix inner rows of eachsubplot were harvested, dried,threshed and then grain and strawyieldswere determined at 14 % moisturecontent and converted into t /ha.Some Economic parameters wereestimated namely; gross return, netreturn and benefit; cost ratioaccording to the data collected undersaline soil. The cost was estimatedaccording the economic evaluation citedby RRTC teams during finalresults of 2005 and 2006 seasons,respectively. The data of eachseason were imposed to thestatistical analysis of varianceanddifferences among treatments means ofthe studied traits were judged by

LSD at P ≤0.05% level ofsignificance according to Gomez andGomez .(1984)

Results and DiscussionsA-Growth parametersA.1.Rice varieties performances:The tested rice varieties showed markedvariation in their growth parameters inboth seasons (Tables 1, 2)

The data listed in table (1) came toprove the fact that

hybrid of SK2034H and SK2046Hperformed better and surpassed theinbred ones regarding dry matterproduction and leaf area index (LAI)as well as panicle length .TheSK2058H hybrid failed to getout any observable variation overGiza 178 inbred one .In addition ,amongst the inbred ones Giza 178 wasthe best regarding LAI , and dry matterproduction .Giza 177 salt sensitivevariety was inferior to others andSakha 104 intermediated the Giza177 and Giza 178 .Couple hybrids of SK 2034H and SK2046H were at the same level ofsignificance in dry matter and LAIin the two year of study andSK2034H gave the highest values ofthem . As for plant height, Sakha104 surpassed the rest of varieties andproduced the tallest plants withoutany significant differences withthose of Giza 178, SK2034H andSK2058H in 2005 season while withSK2046H in 2006 season. The shortestplants were given by Giza177. Thelongest period from

sowing to heading was given by SK2046H, while Giza177 gave shortest period from sowingto heading in 2005 season and SK2034Hin 2006season .SK2046H gave thelongest panicles in the first seasonwhile, couple hybrids of SK2034H andSK 2046H gave the same and thehighest value of panicle length in thesecond season. The shortest panicleswere produced by Giza 177that confirmed its saltsensitivity. As, it wasdetected, SK2034H and SK2046H couldbe characterized as salt- tolerantvariety .The superiority ofnominated hybrids under salt stressmight be owing to its high seedingvigor, faster and early growth,high efficiency of theirphotosynthesis and metabolismprocesses. Furthermore, its highnutrient uptake ability and optimumcanopy index leading to producing moredry matter at pre heading. That mightbe contributing to high yieldpotentiality. The current resultsare in a good accordance withthose reported by Zayed, (2002),Singh, (2002), Patil et al.,(2003),Abdel Rahman et al. ,(2004) ,Gautam(2004), Abou Kalifa (2005) and Zayed etal., (2006)

A.2. Potassium effect:Rice growth parameters showed significant response toincrease potassium rates up to 72 K2O/ha under such circumstances in the two years of study (tables1, 2).Increasing potassium rates certainlyenlarged leaf arearesulted in reasonable LAI and pushed rice plants to grow faster during vegetative growth stage and healthyalthough stress producing more dry matter productionwith less catabolism because hazardous stress. In addition,

increasing potassiumrate significantly

encouraged cell division and elongationresulted in tallestplant and longest panicles thatwas fact with increasing potassiumrates up to 72 kg K2O /ha. Also,potassium rates up to 72 kg K2O /hasignificantly affected heading dates.It was recognized that riceplants which was receivedpotassium at any studied rate upto 72 K2O/ha were flowered earlierthan those of control plants in theterms of which didn’t receive anypotassium .As before mentionedpotassium eliminated the undesirableeffect of salt and pushed rice plantsto grow normally and faster as well ashelp plants to form flowering hormonesas soon as early resulted in earlyheading than those of control plantsZayed et al.,(2006) stated thatsalt stress delayed floweringand shortened the activegrain filling period .The effectivephysiological role of potassium suchkeeping cell turgid under saltstress, enzymatic activity andreducing Na uptake contributed toconsiderable rice growth undersuch conditions. In addition,role of potassium in relieving theions imbalance might be enable riceplants to withstand the saltstress. the role of potassiumin promoting assimilatestranslocation from leaf tostorage organs enhancedphotosynthesis and produce more drymatter as well as enlarged the leafarea index to the optimum limit. Theobtained results are in a goodconformity with those referred byMuhammad and Neue, (1987), Sharmaet al., (1995) Qadar, (1998),Zayed,. (2002) and AbdelRahman et al., (2004).

54

Traits Na+ leaf conte

K+ leaf conte

Na+ /K+rat

PanicleNo/m2

Filledgrains

Treatments 2005 2006 2005 2006 2005 2006 2005 2006 2005 2006Varieties

Giza 177 756 759 513 508 1.55 1.57 270 250 99 98Giza 178 559 564 593 589 0.94 0.94 375 355 129 128Sakha 104 642 633 530 525 1.21 1.24 363 335 127 125SK2034H 630 634 627 622 1.04 1.01 433 415 139 137SK2046H 550 552 667 663 0.83 0.84 410 380 138 137SK2058H 696 698 546 540 1.32 1.36 378 350 111 113

LS D(0.05) 24 15 13 13 0.06 0.05 33 31 13 12K level Kgk2o/ha0 729 733 504 500 1.49 1.51 318 293 107 109

24 678 681 541 537 1.27 1.30 350 328 121 12048 611 613 600 595 1.03 1.03 390 365 131 12072 530 533 672 666 0.79 0.80 428 408 137 135

L.S. D(0.05) 15 9 9 9 0.04 0.05 15 14 5.40 1.90Interaction ** ** ** ** ** ** NS NS ** **

B. A. ZAYED etal.,

Table (1): Dry matter g/m2(DM), Leaf area index (LAI), heading date, plant height and panicle length of some rice varieties as affected by potassium rates in 2005 and 2006 seasons.

Table (2): Na+, K+ mmol /kg and their ratio in leaf at heading, panicle numbers /m2 and filled grains of some rice varieties as affected by potassium rates in 2005 and 2006 seasons

Table (3): Unfilled grains, panicle weight, 1000 grain weight, grain and strawyields of some rice varieties as affected by potassium rates in 2005 and 2006 seasonsTreatments Unfill

edgrains/

Panicle

Weight(

1000- grainweight(g)

Grainyieldt/

Strawyieldt /Varieties 2005 2006 2005 2006 2005 2006 2005 2006 2005 2006

VarietiesGiza 177 18.40 17.60 2.90 2.79 27.30 26.99 4.58 4.42 6.96 6.80Giza 178 13.70 12.60 3.18 3.06 20.50 20.04 6.27 6.08 10.5

310.34Sakha 104 16.20 15.00 3.50 3.40 27.50 27.00 5.50 5.37 10. 9.82

SK2034H 49.40 45.00 4.17 4.03 21.60 21.28 7.26 6.97 11.17

11.00SK2046H 18.30 16.80 3.44 3.43 25.40 24.70 6.78 6.61 10.8

110.72SK2058H 74.70 70.20 3.10 3.02 24.70 24.01 5.56 5.46 10.4

310.22LS

D(0.05)5.20 4.00 0.38 0.37 0.80 0.81 0.60 0.61 0.89 0.81

K.Kgk2o/ha0 45.40 42.00 2.88 2.73 23.10 22.67 4.96 4.82 9.26 9.0624 33.30 31.40 3.20 3.11 24.50 23.87 5.64 5.50 9.82 9.6448 27.60 25.30 3.60 3.52 25.10 24.60 6.24 6.10 10.3

110.1272 20.80 19.50 3.89 3.80 25.20 24.87 7.12 6.84 10.5

110.42L.S.

D(0.05)1.90 2.00 0.08 0.07 0.50 0.28 0.22 0.21 0.25 0.22

Interaction

NS NS ** ** NS NS ** ** NS NS

Traits

Treatments

DM g/m2LAI Heading

datePlant

height (cm)Panicle

length(cm)2005 2006 2005 2006 2005 2006 2005 2006 2005 2006

VarietiesGiza 177 844 838 3.57 3.56 92.0 91.8 99.7

992.80 18.94 18.60

Giza 178 1554 1545 4.66 4.60 99.0 100.3

100.90

99.90 20.68 20.40Sakha 104 1456 1449 4.26 4.17 98.0 102.

0107.46

106.40 21.52 21.20SK 2034 H 1764 1750 5.54 5.51 101.

0100.7

104.74

103.70 24.03 23.50SK 20 46H 1762 1748 5.56 5.42 104.

0102.4

100.80

99.80 24.49 23.50SK 2058 H 1578 1564 4.65 4.54 93.0 91.0 97.4

796.50 23.10 22.10

L.S. D(0.05)

60.80 55.30 0.24 0.23 1.7 0.9 6.36 6.30 0.83 0.80K level kgk2o/ha0 1410 1398 4.26 4.17 99 100.

197.47

96.50 21.35 20.6024 1471 1458 4.53 4.45 98 98.8 100.

5099.50 21.97 21.40

48 1522 1516 4.85 4.77 98 97.4 101.61

100.60 22.38 21.8072 1567 1558 5.18 5.12 97 96.2 103.

83102.80 22.79 22.20

L.S. D (0.05) 10.29 11 0.12 0.11 0.44 0.37 0.93 0.92 0.22 0.20Interaction ** ** NS NS NS NS NS NS NS NS

55

DM

A.3 .theinteractioneffect:The analysis of variance showedthat the interaction between ricevarieties and potassium rate hadsignificant effect on dry matterproduction /m2 in the two seasons ofstudy (Table 4). Regardingvariation response to potassiumfertilizer among varieties inbred/hybrid, all rice varietiessignificantly responded to potassiumrates up to 72 kg k2O/ha in bothseasons based on their dry matterproduction .The highest values of drymatter was produced by SK2046Hwhen it received the highpotassium level of 72 k2O/hafollowed by SK2034H under the samelevel .Meanwhile, Giza 177 gavethe lowest value of dry matterproduction under zero potassiumlevel (Table 4). The results ofinteraction came to confirm that thepotassium fertilizer is bad need undersaline soil particularly forsensitive varieties and hybrid ones.Similar results have been reported byZayed (2002) and Abdel- Rahman et al.,(2004).Data arranged in table 2indicated great varietalsdifferences in their Na+, K+ leafcontent and their ratio (Na+ /K+ratio ) at heading. The saltsensitive variety of Giza 177 failedto prevent more sodium accumulationwhereas, it gave the highestvalue of sodium leaf content.Sk2058H came in the firstorder regarding sodium leaf contentat heading . On contrary, SK2046Hgave the lowest value of sodiumcontent indicating its

ability to select potassium againstmore sodium uptake. So, SK2046Hexerted the minimum values of Na+

/K+ ratio in study years. On the otherside, Giza 177 gave the lesser valuesof potassium leaf content. As it wasdetected Giza 177 had lower potassiumcontent and higher sodium leaf contentleading to higher Na+ /K+ ratio.referring its salt sensitivity.SK2058H showed its sensitivity viaits higher sodium leaf content, higherNa+ /K+ ratio and lesser potassium leafcontent at heading (Table 2) .Giza178 came in the second rank regardingthe superiority of low Na+ /K+ratio. In spite of Sk2034H hadhigh sodium content, it also had highpotassium leaf content inducing ionbalance leading to reasonableNa+ /K+ ratio. Muhmmad andNeue, (1987) reported positiveand significant correlation betweenthe Na+ /K+ ratio and the salinitytolerance rather than highpotassium or low sodium leafcontent .Thereby, couplevarieties of SK2046H and Giza178 had high affinity for ionselectivity .which attributed totheir salinity tolerance. Moreover,Sk2034H might be had another mechanismfor salt tolerance such as producingsome osmolytes. From goingdiscussion, Sakha 104 could becharacterized as moderately salttolerant variety .Similar data havebeen emphasized by Lee and Senadhara(1996), Zayed. (2002), Abd El Rahamnaet al., (2004).

Table(4): Dm ,filled grains /panicle and panicle weight as affected by the interaction between rice varieties and potassium rates in 2005 and 206 seasons

Varieties K Levels Kg

Filledgrains

/panicle Panicle wt (g)K2o/ha 2005 2006 2005 2006 2005 20060 780 774 86 85 2.54 2.46

Giza177

24 823 816 94 93 2.78 2.6848 865 861 102 101 3.00 2.9172 908 902 115 114 3.28 3.130 1475 1465 118 116 2.79 2.65

Giza178

24 1528 1513 125 123 3.04 2.9148 1585 1580 135 133 3.33 3.2472 1628 1623 139 138 3.56 3.450 1343 1334 113 111 3.05 2.88

Sakha104

24 1440 1430 126 124 3.38 3.2848 1500 1501 135 132 3.69 3.5672 1540 1533 135 135 3.91 3.880 1696 1689 126 124 3.64 3.39

SK2034H 24 1749 1735 135 133 3.86 3.7848 1779 1768 145 142 4.41 4.3172 1823 1808 152 149 4.75 3.640 1677 1653 129 128 2.98 2.83

SK2046H 24 1740 1722 136 135 3.40 3.3648 1794 1786 143 140 3.63 3.5972 1844 1832 147 144 3.98 3.940 1493 1472 69 89 2.28 2.20

SK2058H 24 1548 1533 113 110 2.73 2.6548 1609 1599 127 123 3.54 3.4672 1663 1651 136 132 3.85 3.75

LSD 0.05 25 27 13 5 0.14 0.18Giza 177 failed to prevent more sodium accumulation

B. Na+, K+ and Na+ /K+ ratio: B.1. Rice varieties performance:Data arranged in table 2indicated great varietaldifferences in their Na+, K+ leafcontent and their ratio (Na+ /K+ratio) at heading. The saltsensitive variety of

whereas, it gave the highestvalue of sodium leaf content.Sk2058H came in the first orderregarding sodium leaf content atheading . On contrary, SK2046H gavethe lowest value of sodium contentindicating its ability to selectpotassium against more sodiumuptake.

56

So, SK2046H exerted the minimumvalues of Na+ /K+ ratio in studyyears. On the other side, Giza 177gave the lesser values of potassiumleaf content. As it was detected Giza177 had lower potassium content andhigher sodium leaf content leading tohigher Na+ /K+ ratio .referring itssalt sensitivity .SK2058H showed itssensitivity via its higher sodiumleaf content, higher Na+ /K+ratio and lesser potassium leafcontent at heading (Table2). Giza178came in the second rank regarding thesuperiority of low Na+ /K+ ratio. Inspite of Sk2034H had high sodiumcontent, it also had high potassiumleaf content inducing ion balanceleading to reasonable Na+

/K+ ratio. Muhmmad and Neue,(1987) reported positive andsignificant correlation between theNa+ /K+ ratio and the salinitytolerance rather than highpotassium or low sodium leafcontent .Thereby, couplevarieties of SK2046H and Giza178 had high affinity for ionselectivity .which attributed totheir salinity tolerance. Moreover,Sk2034H might be had another mechanismfor salt tolerance such as producingsome osmolytes. From goingdiscussion, Sakha 104 could becharacterized as moderately salttolerant variety .Similar data havebeen emphasized by Lee andSenadhara. (1996), Zayed. (2002),Abdel Rahaman et al., (2004).B. 2. Potassiumeffect:Potassium levels pronounced affectedsodium, potassium and their ratio inthe first and second seasons,respectively(Table 2). Each increment unit ofpotassium fertilizer upto 72 kg k2o /ha significantly reducedsodium leaf content and Na/ K ratio ,while increased potassium leaf contentat heading(Table2)The responsive ofrice plants topotassium up higherlevel might be mainly due to

potassium deficiency as it wasindicating in the materials, andmethods and sodium interference withit under salt stress. It isbecame fact that increasingpotassium availability in soilsolution around the root growth zoneis more effective in reducing Na+influx into rice plant. Therefore,potassium fertilizer enable riceplants to avoid the hazardous effectof salt such as destroyed the cellmembrane and restricted the growth andother metabolism processes. Potassiumfertilizer confirmed its effective todiminish the Na+/K+ ratio resulted inmore salt tolerance. The higherpotassium level of 72 K20 /harecorded the minimum values of Nacontent and Na+/K+ ratio and themaximum values of K+ leaf content.Meanwhile, zero level of potassiumgave the highest values of Na+ andNa+/K+ ratio and the lowestvalues of potassium leaf content atheading .Muhmmad and Neue, (1987),Qadar (1998), Zayed ,(2002) , andAbdel Rahman et al., (2004) statedsimilar results .

B.3. Theinteraction effect:The data in table5 showsignificant effects by theinteraction between rice varieties andpotassium rates on Na+, K+ and Na+ /K+ratio in leaf at heading in couple ofseasons. Increasing potassium rates upto 72 K2O/ha was found to be effectiveto prevent more Na+ influx into planttissues of sensitive ones suchas Giza 177 and SK2058H .Inthe first season, sodium leafcontent of Sakha 104 didn’t respondto potassium increasing beyond thelevel of 24 K2O/ha .Generally,increasing potassium rate succeededto reduce sodium uptake andincreased potassium uptake andsubsequently lowered Na+ /K+ ratio.That was fact with all testedcultivars, particularly the sensitiveones. Zayed, (2002) showed similarfindings.

Table (5): Na, K leaf content and their ratio at heading as influenced by the interaction between rice various and potassium rates in 2005 and 2006 seasons.

Na+ mmol/kg K+ mmol/kg Na+ /K+ ratio

Varieties K. Levels Kg K2o/ha 2005 2006 2005 2006 2005 20060 886 889 410 406 2.18 2.2124 799 804 444 439 1.80 1.83

Giza177 48 736 734 581 577 1.26 1.2772 601 68 616 611 .097 0.990 626 631 545 541 1.15 1.1624 579 583 579 575 0.95 0.97

Giza178 48 538 543 606 601 0.88 0.9072 495 500 642 638 0.77 0.780 679 684 456 451 1.49 1.5624 622 666 503 498 1.31 1.39

Sakha104 48 613 616 536 531 1.14 1.1172 565 568 626 620 0.90 0.900 730 735 553 548 1.31 1.2924 684 689 591 588 1.15 1.13

SK2034H 48 594 597 653 649 0.91 0.9272 514 516 714 702 0.72 0.730 637 642 603 598 1.05 1.0324 577 577 641 638 0.88 0.91

SK2046H 48 532 533 686 681 0.77 0.7872 456 458 739 735 0.61 0.620 814 817 459 456 1.77 1.81

SK2058H 24 768 770 489 485 1.54 1.5948 656 658 540 530 1.22 1.2472 546 548 698 691 0.78 0.79

LSD0.05 37 21 22 21 0.1

0.1157

B. A. ZAYED etal.,

C. Yield and yield components: C.1. Rice varieties performance:

Data in table3 show that all tested rice varieties

significantly varied in their strawyield, grain yield and all yieldcomponents. Couple hybrids ofSK2034H and SK2046H surpassed allinbred varieties involving the bestone (Giza 178) in panicle numbers/m2, filled grains, panicle weight,grain yield and straw yield inboth seasons. Furthermore, the twohybrids of SK2034H and SK2046 were

comparable in the most ofaforementioned traits except,panicle weight whereas, SK2034H gavethe heaviest panicle, maximum valuesof panicle numbers, filled grains,grain yield and straw yield .Thenominated two hybrids were at a parwith Giza178 in filed grains .SK2058Hdidn’t show any advantage over thebest inbred or Sakha 104. Giza 177 wasinferior whereas, it gave the lowestvalues of yields and yieldcomponents except, 1000-grainweight. Sakha 104 produced theheaviest 1000 grain weight withoutany significant differences withthose produced by Giza177.SK2058H had the maximum values ofunfilled grains followed by SK2034H.It seems that SK2034H didn’tshow it higher yield potentialityowing to the higher rateof sterility. So, improving grainfilling through using goodintegrated crop nutrient managementprogram has todevelop for getting out itshigher yield potentiality.Interestingly, good growth atpreheating, relieving salt stressand high photosynthetic rate atpost – headingcontributed to the higher grain yieldof elite hybrids andinbreeds under such conditions. Thepresent finding are in a goodaccordance with those reported byZayed et al.,(2002), patil et al., (2003),Gautam. (2004), AbdelRahman et al., (2004), Abou Khalifa.,(2005) and Zayed

seasons ,respectively .Regarding theeffect of interaction on filledgrains/panicle ,it was found that bothvarieties of SK2034H and Giza 177significantly responded topotassium fertilizer up to high levelof 72 kg k2o /ha .The rest of inbredand hybrid varieties significantlyresponded to potassium level of 48 kgk2o/ ha regarding filled grains/panicle (Table 5). On the otherhand, panicle weight of allinvestigated varietiessignificantly responded topotassium fertilizer up to 72 kgk2o /ha .Sk2034H produced theheaviest panicle weight at highpotassium rate of 72 kg k2o /ha,while the lightest panicle weightwas obtained by Giza 177 under Zeropotassium level (Table ). Withrespect to grain yield, Giza 177(salt sensitive variety) and the threerice varieties; SK2034H, Sk2046H andSk2058H highly significantly respondedto increasing potassium rates up to 72kg k2o /ha in the two years of study( figs 1&2) . However, Giza 178(salt tolerant variety) and Sakha 104significantly responded to potassiumlevel up to 48 kg k2o /ha.Generally, the maximum values ofgrain yield was produced bySK2034H at high level of potassium of72 kg k2o /ha, while Gaiz 177 gavethe minimum value of grain yield atzero potassium level aforementionedresults indicated the need of hybridrice varieties and sensitiveones to increasing potassiumfertilizer particularly under saltstress and potassium deficiency as itwas indicated in the materials.Samarath et al., (2002) and Zayed.(2002) stated similar results.

Response of some indred and hybrid rice varieties to potassium fertilizer under saline soil conditions season 2006

10

et al., (2006).

C. 2. Potassium effect:Potassium fertilizer had

significant effect on grainyield ,straw yield andyield components in the two years of study

(Table3).Each increment

H1H2H5

H1H2H5

G r ai

n y ie

ldGr

ain

yiel

dunit of potassium up to72 kg K2O/ha significantly raised allyield components and grain yield as well as straw yield .Interestingly, the

LSD = 0.538

6

4

2

00 24 48 72

K levelKg/ha

Giza177G178Sakha104SK2034H

SK2046H

SK2058H

unfilled grains significantlywent down with each incrementunit of potassium. The highest valuesof grain yield and yield componentswere produced when riceplants received the high potassiumlevel of 72 kg k2O/ha. Meanwhile thelowest values of them were recordedwhen rice plants didn’t receive anypotassium supporting the benefit roleof potassium under saline soils.The low

Fig.1: Grain of rice as affected by the interactionsbetween rice varieties and Potassium rates in 2005

Response of some indred and hybrid ricevarieties to potassium fertilizer under

saline soil conditions season 200510

LSD = 0.54

sterility under potassium fertilizerproved its useful role in improvinggrain filling under salt stress.Improving growth, promotingphotosynthetic rate at pre- headingand post-heading, increasingassimilates translocation tograins and raising salinitywithstanding with potassium fertilizermight mainly be contributed to highgrain yield under salt stress. Thecurrent finding are in similarity withthose reported by Muhmmad and Neue,(1987), Sharma et al., (1995), Qadar,(1998), Singh et al., (1999) Dwivedi et

8

6

4

2

00 24 48 72

K levelKg/ha

Giza177G178Sakha104SK2034H

SK2046H

SK2058H

al., (2000), Sarmath., (2002), Zayed, (2002), and AbdelRahman et al.,(2004).

C.3.Interaction effect:The interaction between rice varieties and potassium rateshad significant effect on filled grains/panicle ,panicle weight and grain yield in the first and second

58

Fig. 2: Grain of rice as affected by the interactions between rice varieties and Potassium rates in 2006

D. Economic evaluation:Data in table 6 show that the rice varieties differed in their economic parameters. Sk2034H gave the highest values

0 3996 3840 696 540 0.211 0.15924 5016 5040 1616 1540 0.475 0.44048 5856 5748 2356 2148 0.673 0.59772 7140 6816 3540 3116 0.980 0.8420 5863 5753 2563 2353 0.777 0.69224 6523 6303 3123 2803 0.918 0.80048 7513 7315 4013 3715 1.146 1.03272 7700 7381 4100 3681 1.139 0.9950 5904 5652 2604 2252 0.789 0.66224 6060 5988 2660 2488 0.782 0.71148 7020 6828 3520 3288 1.006 0.89772 7416 7308 3816 3608 1.060 0.9750 6490 6314 3190 2914 0.967 0.85724 7458 7337 4158 3837 1.223 1.09648 7953 7744 4453 4144 1.272 1.15172 10032 9295 6432 5595 1.787 1.5110 6028 5865 2728 2463 0.827 0.72424 7128 6875 3728 3375 1.096 0.96448 7568 7458 4068 3858 1.162 1.07272 9141 8800 5541 5100 1.539 1.3780 5313 5192 2013 1792 0.610 0.52724 5995 5775 2595 2275 0.763 0.65048 6380 5907 2880 2307 0.823 0.64072 6765 6655 3165 2955 0.879 0.799

of gross return LE /ha, net returnand benefit /cost ratio followed bySK2046H and then Giza 178 .Sk2058hdidn’t show any advantage in theeconomic parameters over Sakha 104or Giza 178. Giza 177 gave the lowestvalues of estimated economicparameters; gross return, net returnand benefit /cost ratio. Increasingpotassium rate up to 72 kg k20 /hamarkedly improved the economicparameters; gross return, netreturns and benefit /cost ratio.All cultivar responded to potassiumfertilizer up the higher potassiumlevel whereas it gave the highestvalues of studied economic parameters.Giza 177 gave the lowest

economic parameters under Zeropotassium fertilizer while , thecombination of Sk2034H and highpotassium level of 72 kg k2o /hagave the highest value of net return.

Finally, it could berecommended that potassiumapplication at the rate of 72 kg k2o/ha was found to be effective inminimizing the hazardous effect ofsalt, increasing rice growth,improving grain filling process andultimately promoted yield of allvarieties especially, sensitive onesand hybrids.

Table (6): Gross return LE/ha , net return LE/ha and cost/benefit ratio as affected by rice varieties and potassium rates in 2005 and 2006 seasons

Varieties K. LevelsKg

Gross return

Net return

Cost/benefit

K2o/ha LE/ha LE/ha rati o

Giza177

Giza178

Sakha104

SK2034H

SK2046H

SK2058H

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