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CERTIFICATE This is to certify that the thesis entitled "Effect o f surface soil moisture on root growth and yield in rabi sorghum" submitted in partial fulfilment of the requirements for the degree of 'Master of Science in Agriculture' of the Andhra Pradesh Agricultural University, Hyderabad, is a record of the bonafide research work carried out by Mr. Elasha Abdel Hay Elasha Abu Elbashlr under my guidance and supervision. The subject of the thesis has been approved by the Student's Advisory Committee. No part of the thesis has been submitted for any other degree or diploma. The published part has been fully acknowledged. All assistance and help received during the course of the investigations have been duly acknowledged by the author of the thesis.

Thesis approved by the Student's Advisory Committee: Chairman:

Members:

Dr. M. Ranga Reddy Professor and Head Dept, of Agronony and Principal, College of Agr~culture Rajendranagar Hyderabad 500 030 1.

Dr. 8. Bhaskar Reddy Assoc~ateProfessor Depattment of Agronomy College of Agriculture Rajendra Nagar Hyderabad 500 030

2.

Dr. P.S. Sarma Associate Professor Dept. of Plant Physiology College of Agriculture Rajendranagar Hyderabad 500 030

CERTIFICATE

Mr. Elasha Abdel Hay Elasha Abu Elbashir has satisfactorily prosecuted the courqe of research and that the thesis entitled EFFEC'I' OF SURFACE SOIL

MOIS'I'UHE ON ROOT (;KOW'I'H AND YIELD IN KABI SOK(:HUM submitted is the result of original research work and is of sufficielitly high standard to warrant its presentation to the examination. I also certify that the thesis or part thereof h;~snot bee11 previously submitted by h ~ mfor a degree of any University.

Date:

>+'-/ 0 -73

Major Advisor:

pv L

-

Dr. M. Rmga Rerltly Professor and Head Department of Agrono~nyand Principal, Andhra Pradesh Agricultural University, Rajendranagar Hyderabad 500 030

9

CONTENTS Chapter No.

Title

1

IN'I'KODUCTION

11

REVIEW OF LITEKA'rUKE 2.1 2.2

The root system of other crops The root system of sorghu~li 2.2.1 Root. Morphology, Morphogenesis and Functinoal Characteristics

2.3 2.4

Plasticity and Co~npensatoryGrowth Root Growth 111 Relation to Shoot Growth 2.4.1 2.3.2 2.4.3 2.4.4

Root Volu~ncand Mass Root Lzilgth Root/Slloot Ratio Root Length Density

2.5.1 Cli~naticFactors 2.5.2 Solar Kudiation 2.5.3 Temperature 2.5.4 Open-pan Evaporation and Saturation Vapour-Presaure Deficit 26

Edaphic Factors 2.6.1 2.6.2 2.6.3 2.6.4

2.7 2.8

Soil Water Storage Soil Nutrient Content Soil Cracking Soil Temperature

Insects and Disease Proble~ns Management Factors 2.X.l 2.8.2 2.8.3 2.8.4

Date of Sowing Depth of Sowing Irrigation Fertilization 2.8.5 Plant Density and Row Spacing

Page No.

2.8.6 Soil Physical Conditions (Tillage and Other Cultural Practices) 2.9

Growth Regulators

111 MATERIALS AND METHODS

3.1

Experi~nenmlSite 3.1.1 Locntion 3.1.2 Climate 3.1.3 Soil

3.2

Experimental Details 3.2.1 Trenttnents 3.2.2 Experimental Deaig~land Layuut

3.3.1 Plant Cirowth Analysis 3.3.2 Sampling Procedure 3.3.3 Nodal Koot Nutnber 3.3.4 Tohi Zoot Letiytti 3.3.5 Tot;~lKoot Mass 3.3.6 Root I,e~igtli Density 3.3.7 Plant Height 3.3.8 Leaf Number 3.3.9 Leaf Area 3.3.10 Leaf Dry Weight 3.3.1 1 Stem Dry lveight 3.3.12 Shoot Dry Weight 3.3.13 Total Plant Dry Weight 3.3.14 RooVShoot Ratio 3.3.15 Stover Dry Weight 3.3. I6 Biolnass 3.3.17 Yield and Yield Colnponents 3.3.18 Harvest Index 3.4 3.5 IV

Nutrient Analysis Water Use and Water Use Efficiency

RESULTS 4.1

4.2

Climate Underground Portion

4.2.1 Nodal Roots. Total Root Length and Total Root Mass Per Plant During the Season 4.2.2 Nodal Roots. Total Root Length and Total Root Mass Per Plant During Different Growth Srages 4.2.3 Root Length Density 4.3

Aboveground Portioti 4.3.1 Stem Dry Weight, Leaf Dry Weight. Shoot Dry Weight and Total Plant Dry Weight Per Pla~lt 4.3.2 Root/Shoot Ratio 4.3.3 Green Leaf Area (ct,iz) and Leaf Number Per Plant

4.4

Yield and Yield Attr~butes 4.4.1 I'l,int Height, Panicle Lzngth. Grain Number per Panicle, 100 Seed Mas\, Yield. Stover Weiglit, Biomass and Ila~.vestIndex Functiot~of Irrigation and Cicnolypcs 4.4.2 Interactio~~ Effect

4.5 4.6

V

Water Used and Water Use Efficiency Nutrient Analysis

DISCUSSION Under Gvnw!r! Growth During N&! RQQ! Initiation a t ~ dPanicle Initiatioti Above Ground Portion at Early Growth Stages Above Ground Portion at Later Stage? Under Ground Portion at Later Stages Nutrient and Water Uptake Root Length Density Rootishoot Ratio Yield and Yield Attributes

VI

SUMMARY

LITERATURE CITED APPENDICES

LIST OF ILLUSTRATIONS Figure No.

Page No.

Title

1

Temperature (Max. and Min. 'C) and rainfall ( ~ n m )during the growing season.

2a

Soil te1nper;tture ("C) st 2 ctn soil depth.

2b

Soil temperature ("C) at 5 c111?oil depth

3

Nodal root 1nu111bcrper plant at tlie end of the season as o function of irrigation treatmelits.

4

Nodal root n111nberper plant of four genotypes at the end of tlie sexon.

5

Total root lengtl~per plant as a function of irrip:ltion : ~ tthe c11d of the season. Tor;~iroot length per pl:lnt of four genotypes a t the end of tlir se;Ison.

(1

7

Total root mass per plant at the end of the as a function of irrigation treatments.

8

Total root mass per plant of four genotypes at the end of the reuson.

9

Nodal root< ?er plant for irrigation treaunent\ at four growth stages.

I0

Nodal root number per plant of four ge;iotypes at four gruwth stages.

II

Total root length at four growth stages as a function of il~igationtreatlnents.

SC;IS~II

12 Total root length per plant for four genotypes at four growth stages. 13 Total root Inass per plant (g) function of il~igation at four growth stages.

14 Total root mass per plant (g) at four growth stages for four genotypes.

15 Total plant dry weight per plant (g) at the elid of the .\eason as a function of irrigation treatlnents. 16 Total plant dry weight (g) at the end of the season function of genotypes.

17 Aboveground total dry matter production per plant in relatin11 to underground total dry matter production per plant. 1R

Stern dry weight per plant (g) during five growth htages as treatlnents. affected by il~ig;~tion

I9

S t e ~ ndry weight per plant (g) for four genotypes ;it five growth stages.

I0

Leaf dry weight per pld~it(g) during five growth a function of irrigation tle;ltlllents.

21

\IB;CS

Leaf dry weight per p1;111t(g) during five growth stages

BS

;IS

a fu~~ction of genotype\. 22

Shoot dry weight per platlt (g) tluring five growth stage.; ;IS a fu~lctio~l of irrigation trcatmeots.

23

Shoot dry weight per plant (g) during five growth stages as $1 functio~lof ge~iotypes.

24

TCtd ;l:mt

25

Total p!:xt dry weight (g) of four gellotypes at four growrh stoges.

26

Total plant dry weight as a function of irrigation x genotype interaction.

27

Roodshoot ratio as affected by ilrigtion treatments during four growth stages.

28

Roodshoot ratio of four genotypes at four growth stages.

b y weight (g) at focr growth stages fu~lclic!?C? irrigation treitlllents.

29

Yield, stover weight and biomass (Tlha) of four genotypes at harvest.

302

7c soil moisture at 0-50 cln soil depth for irrigatio~iseedling treatments at four growth stages.

30b '70 soil iiioisture at 50-100 c m soil depth for irrigation scedliiig treatments at four growth stages.

LIST OF TABLES Table No.

Title

Analysis of variance table showing degrees of freedom (DF), F-probability (F-PR) for ~iodal root numbers per plant (NRPL"), total root length per plant (TRLPL I) and total root mash per platit (TRMPL1). Mean root ie~lgtlidensity values (ctn/ctn3) for genotypes and irrigation beattnetits at 50% flowering (50LTa FL) atid liarvest (HAR). Analysis of variance table for root letigth density showitif degrees of freetlotii (DF), F-probnbility valuea (F-PK) at 50% tlowering (50% FL) illid h:irvest (HAR). Analysis of variance table for atem dry weight (STDWPL-I), leaf dry wieght (LFDWPL-I), slioot dry weight (SHDWPU') and total plilnt dry weight (TDWPL1) snowing degrees of frcedoni (DFj anti F-probability (F-PR). Mean leaf area and leaf ~illtnberas a functioti of irrigation seedling treattrierits atid getlotypes. Plant height (PLH), panicle length (PNL), grain nutnber per patiicle (GP.NPN1), 100 seed tnass I!)!! SM) yield, stover wig!!! (ETOwT), biomass (B!C?) :n:! harvest index (HI)a affected by irrigation u p s x n t ? . Plant height (PLH), panicle length (PNL), grain number per pirnicle (GRNPN1), 100 seed inass (IUI) SM), yield, stover wcight (STOWT), biomass (BIO), and harvest index (HI) of four genotypes. Irrigation x genotype interaction of plant height (PLH) and grain number per panicle (GRNPN"). Water used and water use efficiency (WUE) at different irrigation treatments.

Page No.

10 Nutrient analysis at flowering and harvest showing the per cent nitrogen and phosphorous at flowering (%NFL). (%PFL), and hawest stages (%NHAR), (%PHAR) and total nitrogen and phosphorous at both stages (TNFL), (TPFL), (TNHAR), (TPHAR), II

Nitrogen and phosphorous percentage it1 the grain ('ZNGR. %PGR) and total nitrogen and phosphorous both in the grain and the whole plant (TNGR; TPGR; TNWP; TPWP).

12

Relationship between root length density (RLD) at harvest ant1 yield.

13

Probabilities of differences among treottnents for various measures of crop growth during nodal root itiitiatioli (NRI), panicle initiation (PI), 50% tlowreing (50LioFL) and harvcxt (HAR).

Altltorr,qlt 1 firrd i t possiblc to nrerrtiorr olily o feu), brrr I sirrcerely cippreciote eacli o ~ r cwho co~rtribrrtctlton~irrdsthe cor~rpletio~r of titis thesis. Deep crrrrl sirirere firmtitude to D r . F.K. Birlilrger. Prbrr.ilial Scie~rrisr (Pkysiolo,qyJ, Cererrls Plrysiolo,py, I ~ r r ~ ' r ~ i ~ r t iCrops o ~ r o l R ~ s ~ N111,vr;trife ~ c ~ I f h r the S ~ n r i - A r i r lTr,o/~ics(ICHISAT). Co-Clrciirnrrir~ [if my r i d ~ , i s o ~r~o~~rrrrittee, y ftir hi.! ~ ~ u l u o b,prridarrc~r. le c'o~rstr~rc~tive criticisni fh~.o~i,qhout the per i r ~ irfthis l iiri8esti,pritiorr The Iecrr.~ri~rg etparioicr iorrler iris diwctiorr cr~ior~tfirrrl~ its ro~rtrihrrtiorrrr~wordsthe ~rrrc'casfirlconi~iletiorrof'rlre rliesis, wris olso hdlJfil/ as o firtiwe ieuriiiiig e ~ ~ ~ e r i e r i c e to nie.

I

~ I I Iril.\o

lii,yiiiy tliorikfiri to D r . M . K t i ~ ~ , p/I(crirly, (i Prr~f'esso~.ctrril Hctrcl,

& / ) ~ l f t t l r l i~l f A j i l ' ( l l l ~rllld ~ i ~I /,I C Prillc~jJ(ll( f ' t h ~(:lJ//I!ge ~ f ' ~ , q l ' i r ' l l / / l l rAlldhrii e, Pro(lc.!ii Agricu/trrr.u/ lJriivt,r.\i/y (APAU), Roj~~rje,~h.ti~rcr,qor, /lie Choirrilrm of nly tit11'i~ol'j~ ' < n ~ w i i /ft it I000 ni above sea level. Tlia I:~l.gegellotypic diversity of sorghum iiiakes the crop adaptable tu tilost rrgions where ~naizeor ~iiilletcan be grown (Seethi~ralnaer oi.,19x8). Sorgl~utnoc~upiesabout 47 ~iiillionIia worldwide c ~ i;ISa le;!di~igco!?clnetit, C.'!!c\i'erl with Asi:! (!Y.h ~ i i ~ l l iIi;l)

by Afric:! (15.7 mil!io::

ha), Nolth and Central Aiiier~ca(2.7 lnillio~~ ha). Austrdlia (0.73 lnillioli ha) and USSR (O,lX million li;l) (Doggett, IOXX). Maxi~iiulnharvested yields of > 15 Tihn in the temperate and >X Tih! in tlie semi-arid tropics have been reported (Seetharamil et (11.. IYXX), but average farmers yield in the semi-wid tropics (where the lnajority of the crop is growiij are ahout 0.X Tiha, in comparison to 3.6 T h a in the high technology, temperate regions.

Agroclimatology of Sorghum

The potential yields in the semi-arid tropics are limited by the length of the growing season which is determined by the seasonal rainfall and the water-holding

4

capacity of the soils (Seetharama et (11.. 19x8).

Total rainfall, its length.

distribution, and intensity affect, plant growth such as seedling emergence, early leaf and root growth and ni~trientuptake.

The growing seas011 i11 Africa ranges froin 90 diiys in the Sahel and Sudan Savanna vegetation zones to 270 days towards the equator. The soils of Africa especially in the west are Alfivols poor in nutrients (especially phosphorouh) and c;ip~city. with low water-l~oldi~ig

In the sorplioin growing r e ~ i o n sof 111di;l.the lecigtli of tht: growing seicson ranges between 00-IXO days.

These regio~is(about 80%) fall cnostly under

Vertisols or AIfisols .Ire fertile enoi~glito sustain cnodest yieltlv except where there are acute nitrogen, phosphorouh or zinc def~cie~lcies.The distinctive feature in sorghi~~ii p r ~ d u ~ ti ir ~~Itidiil i ~ ~ is the cultivatioc~of up to 40'h of the total ?1orphu11i area 011stored moisture in the vertisols of the Deccan region (Seetharamn, IYXX).

Average solar rndintion in the semi-arid tropics (17-21 nijim2/day) is adequate during the season.

The temperature extremes are Inore criticiil in

determining crop growth and yield (Peacock and Wilson, 1984). The optilnu~n temperature for photosynthesis is about 40°C, and 30-35°C for growth (Eastin, 19x3). High temperature especially during years when rains end early, !nay result in severe terminal drought stress. High temperature during vegetative growth may be less critical than early or late stage especially if roots have access to water (Seetharama, IYXX).

5

Postrainy season sorghutn in lndia is the third tilost important Indian cereal aocou~itingfor 13 per cent of the gross cropped area in the semi-arid parts of [he country (Tarhalkar lY8h). It is grown on about I6 million ha including both the rainy (June-September) and posuainy or rirbi (September-February) seasons (Seetharama er (11.. 1990).

During rmhi. ~iiostlyit is \owti in the Deccan plateau between 10 and 2O0N latitude coveritig :nure than the latid occupied by tn;lize and more than half of that planted to pearl ~ ~ ~ i l l Despite rt. tiiis, ~.i~bi \orglium accounts unly for less that1 30 per cent of the annual sorghu~nproduc~ion(Tandon iu~dK;~llwar,ICJX4). Average farmer's yields are about 0.5 'l'lhn. In contrast to its rainy se;tron counterpart, the I.(/!>!

sorghutn yield' !:::ve rem:iitied stagnant (Vi:!y:b!lush:t:im,

IYXT,), despi:e its

good grain ;and fodilrr quality. The possible reasons for the low productivity of

rcrhi sorghum are environtnental (clitn;ltic and edaphic) and manngelnent factors (Seethara~naer

(I/., 1990).

Nodal Kuut Systern

Since there is about 6 ~iiillio~l ha in India grown #duringthe postrainy (rohi) season in drying soi!:, it becomes important to have rapid seedling establishment for high and stable yields (Sotnan and Seetharama, 1992). The early vigour is critical if the crop is to use nutrient from the rapidly drying upper soil layers and reduce evaporation from these layers. Both seedling establishlnent and early crop vigour in the rohi sorghum environment depends largely on the rapid initiation and

6 extension of the crown or nodal roots, as the single seminal (primary) root of sorghum usually lasts for 10-30 days after sowing (Freeman. 1970). Bur er 01. (1977) found that setninal roots can retnain active for a longer period when nodal root initiation is delayed, but they can not absorb adequate nutrient and water to sustain plant growth. Blutn and Ritchie (19x4) found that when the top 0.3 111 soil layer is wet (701;/0field caliacityl, nodal root initlation and establishment proceed i ~ at maximum potentiill rate, but the develop~ncntof ;I seco~idaryroot system can be prevented or tlelsyed if ~noistureis deficient ; ~ the t crown depth (Cornish el rrl., 1984).

Sontan atid Seetllitrn~n;~ (1992) have foutitl genotypic variation in thc time of nodal roo!. i!iitiotig~! :!ti11 nodill root length, but !!c.t

it1

nutnber. They also

reported that the va~i;ltionill the growth of the root XI tntii) may aeverely affect water and nutrielit uptake from the top soil layer.

2.8.3 Irrieation

Tarlialk:~~ (19x61 estim;~tsd tliat about less than 12 per cent of the rrrhi wrghum is irrigdted, usually once or twice (Illring the season. Percentage of yield g;litis ranged from 414 per cent (Hari Krislin;~, 10x1); 133-225 pel- cent with one illid 284-41 1 pel cent with two irrtg;~tiotis:I.; cotnpared to ilryland crops (Verma, 1978). Plnut rr (11. (1969) reputted that r no st of [lie grain sorghum yield was obtained with three trrigo:ion or with two i::igations :vlieii the second -as applied hctwee~ihe;~dlngant1 11iilk \rage. They ;~lsoreportetl the mitin yield co~liponellt oft'ectetl by irrigation was 1000 gr:tin 1n;iss.

2.8.4 Fertilization

Kanwar

ct (11.

(19x4) sliowetl that water use and water use efficiency can

both be significantly iiicreased with nitrogen fenilization. The optimum nitrogen varied from 25-85 Kgiha, while the optimum phosphorous was about I I Kgha. Rego et ol. (19x2) mentioned the advantage of deep fertilizer placetnetit in receding ~noisturesituations during rcrhi.

20 Under intensive cropping, phosphorous and potassiu~nnutrition is important, phosphorous as a promoter for root growth (Venkateswaralu and Venkatasubbaiah 19x4) ant1 potassiutn for better grain growth and leaf-water relations (Beaton and Sekhotl 19x5) 2.8.5 Plant Density and Row Spacing A plant drlisity of 40.000- 135,000 pl;intsh;i :ind a row spacing of 75-00 cln is reco~nmellded(CRItIA. IYXO), but farmers use narrow rows of 30 c111 wit11 high densities to 1naximi7.e fodder yield and quality. The practice was found to subject hi sorglit~~ii to tertnilial stress a.i well as root and stalk-rots (ICRISAT, 19x3).

2.Xh Soil Physical Conditions !'!'illaee

and Other Cultura! !'racticesl

(iencrally rout growth is promoted ill a well-cultivated highly drained soil due to better root penrtration. Baligar and Nash (1978) found greater root length in coarse (2-6 mm) than in fine aggregated soil; however, slnall aggregates resulted in greater nutrient availability to roots. Baligar et.al. (10x1) found that a bulk density o i 1.85 Mg m' affected sorghum root growth adversely. Choprat and Nicou (1976) found that deep ploughing before sowing illcreased root densities. ICRlSAT (1986) showed the advantage of deep tillage in Alfisols on root growth. The author recorded yields of 3.22, 2.76. 2.52 Tiha for deep ploughing (0.25 m), mold board plowing (0.15 m). and traditional tillage (0.1 m) respectively.

Wright er (11. (1083) found no effect of gibberellic acid application on root growth, but ill pot experilnc~its~iaphthaleneacetic acid (NAA) and cycoccl (CCC)

spray illcreased root Inass.

MATERIALS AND METHODS

MATERIAL AND METHODS

3.1

EXPERIMENTAI. SITE

The experiment was cunducted at ICRISAT Center (Intlii~)during 1992 wbi SCLISOII. The site is locatetl ; ~ at n altitude of 545 In ;lbovc sea level, IX"N, 7X"E in Parancherti village, state of Andhr:i Prudesh (ICRISAT, IOXS).

The c1im;lte of ICRISAT C e ~ ~ t 1s e r;I typical semi-arid tropical environment characterized by a ~ h o r period t of rainf~ll(3-4 rnonths) and a prolonged dry spell (8-9 months).

Three distinct seasons characterize this environment:

o

Khurifor monsoon season, which usually starts in June and extends into early October during which Inore than 110% of the total annual rainfall (760 ~ n m )is received. hi this season rainfed crops are raised (ICRISAT, 1989).

o

Rabi or postrainy season extending from mid- October to January. This season is relatively dry, cool with short days. Cropping is done on stored

23 soil moisture. The experitnent under study was raised during this season. o

Summer, the hottest season. It starts in February and continued till rains cornmence in June. Usunlly crops are raised under irrigation. The mean seasolual m;~ximum tenlperature is 32.5"~and the minimum is 10.O"~.The daily pan evaporation ranges from 0.6 to 7.2 11un.

The experitnenlul site uhed was ;I Vertisol (Typic Pellu~tert.Kosireddipalli series), ~ n e d i u ~deep u (1.5 m) with o pli of 8.5. EC of 0.58 m. ~nhos/cm,organic carbon of 0.4'7i and 3.2

'1

bulk density of 1.3 Ucc.

EXPERIMEN'L'AI, 1)EI'AII.S

3.2.1 Treatments

Three irrigation levels were used. Tllese were: 1)

No irrigation or control(10).

2)

20 mm irrigation level given at nodal root initiation (11).

3)

20 ~ n at ~ nnodal root initiation plus 25 lnm at panicle initiation making a total of 45 ~ n l n(12).

All irrigations were given using sprinkler system during the night time when wind velocity was at a minimum. The germination of the crop was effected by 20.4

24 lnln rainfall received ilnlnediately after sowing.

Four genotypes differing in their root characteristics were used ( Somun p and Seethara~naN 1992). Eacli genotype was repeated twice to give two sets. The genotypes were:

I)

E3h-I

2)

LAKAIII

3)

M35-1

4)

NAGA WHITE

3.2.2 Experimental Desia~inntl 1,avout The trrattncilts \$ere arranged

ill

a split plot design with nested classification

ill tlie subtle;ltments, with two repitcations.

Main plot tre;itriients were three irrigation levels and tlie Sub plot treatments were four genotypes repeated twice within each tn;~inuentmerlt giving two sets (or four total plots ) for each genotype x treatment i~iteraction. The field layout of the experiment at BL3 during mbi season I992 is as foiiows:

I1

I

Field layout of the experiment at EL3 during rabi season 1992. Main Plots (lrrigat~onlevels) I, = Control (no irrigation); I, = 20 mm at nodal root initiation; I, = 45 mm, 20 mm at nodal root initiation t 25 mm at panicle initiation Subplots (genotypes), each repeated twice to give two sets 1 = E36-1; 2 = Lakadi; 3 = M35-1; 4 = Nagawhite

C = Center plot grown by M35-1 for mooisture observation B = Border plot also grown by M35-1. Gross plot size = 9 x 3 m Net harvested area = 2.5 x 1.5 m

26 The gross plot size was 9 meter length, 4 rows width, with a row spacing of 75 cm between rows. Total experimental area was 17x2 m2 Before sowing a basal dose of 125 K@a urea a~id75 Kgha of dialnlnonium phosphate was incorporated. Sowing was carried out using a precision John Deer Planter with four units. Seedling were thinned to n final spacing of 15-20 cm between hills at 3 weeks after enlergence. Intensive weed cont~ol(~n;lnt~nl) and pl;~ntprotectioll 111cilsu1.e~ :~gai~ist pests. ~naililythc h o o t tly, werc c;lrrieil out whenever Iiecessaty.

3.3.1 PI:lnt (;row111 Analysis The platlt growth ;111;1lysiswas done for both the root 2nd the shoot systelns starting two weeks after the eliierge~lceof the crop (2 WAE). A) Underground portion

Plants were saliipled at four different growth stages. These were;

I)

First saniple at nodal root initiation 2 WAE.

2)

Second sample at panicle initiation 3 WAE.

3)

Third sample at 50% flowering of each genotype 7-9 WAE.

4)

Fourth sample at harvest stage of each genotype 14-16 WAE.

3.3.2 Sarnoline Procedure

During early growth stages (~lodalroot initiation, panicle initiation), as the pl;rnts were still young, coring for roots was not done. Illstcad pl;lt~Lswere sampled by digging directly to an approximate depth of 60 to 75 cln. The nil11 was to recover as ~lluch;Ir pohsible of their root systems. The area sa~npledwas 50 cln leilgtli of two rows (1.5 ~ n ) .At I;lrzr growth stages (50% tlowcri~lgdnd harvest) and as the root syatellls of the differe~ltgenotypes were well developed, a coring [nethod was used to estimate root gmwth. The following procedure was ~dopted:

I)

A sa~liplingarea of two rows each 50 cln Iengtli was conhidered.

Plillit~ ill thil; ; ~ r wcre ~ a clug out to :lbout 25

to

30 c ~ nto rrcover a11

the 1noi1;1l;~ndb~;lceroots ;ittnched to the shoot ( i t 110dul~lomber). 2)

'Thc top 10 clii soil (after pI;lnts were dug) was removed and all visible rernaini~lgroot5 collected. The weight of the coil removed fro111this area was recorded.

3)

A rubsample of 10 Kg loose soil was taken, soeked in water

overnight, sieved thoroughly to recover most roots. 4)

Six cores, each I00 cm deep were taken in the sampling area after the 10 cln top soil removed. This was carried out by a coring cylinder 5 cm in diameter. The soil from the cores was also soaked in water overnight, sieved thoroughly and roots recovered.

5)

The root weight in both loose (I0 cm top soil) and core soil (100 cm

28 deep) were measured for each sub sample.

6)

Total root weight on the top 10 cln wi~scalculated from the sub sample.

7)

Total root Irngth was also calculated to the total s a ~ n p l i ~area ~ g from the sub s ; ~ n ~ pcores. le

X)

The total root weight frum both tlie 10 c111 top soil and tlie 100 cln veil depth giive ;In estimate to the total root weight for each

genotype at each irrigi~tion!re:~t~ne~it.

For total root length, the thick root portio~iswere ~neasuredby a \tale. For the thin portions a sub ~ a ~ n pof l e 0.5 g (fresh weight) of the 10 c ~ ntop soil and of

5 g for the colr sunples were considered. Tlle lengtll of these was deter~nined wing ;I Delta T Area liicter sepamtely. Totill lc~lgtl~ from both tlie top 10 cin soil and the cures were calcu1;lted b;~setlon the total root weight for each p~~rameter.

The parameters recorded for tlie underground portion were: 3.3.3 Nodal Root Nur~iber

Nodal root\ number were deterlnined at each growth ,tiage for each sample by counting directiy.

3.3.4 Total Root Leneth

For this parmliieter the salnple was separated into two portions;

i)

The thick roots (> 0.5 111111dinlneter)

ii)

Tlle thin roots ( < 0.5 mm dia~neter)

I>uring early st;iges (nodal root i~~itiation, panicle initiation), all roots were their length was !measured directly uaing ;I Delra T Are;[ thin and ;~ccortl~ngly Meter (MK2) to give an estimate for nodal root length. D u r i ~ ~later g stages (50% flowering, Ilnrvest), root.; bec;ltne thicker. The thicker portion was measured by n scale, the thin portion by a Delta 1' Are;, Meter (MK2). The values of thicker anti thinner roc.! per!lolis g:!ve an est1111ateof total no:!

root length at !hehe growth

I roots. stages. Koot lziigtii Ine;i.;urelliznl was I,~ken~ I fresh

3.3.5 Total Koot Mass Rooe were transferred to an oven at XVC after their length was ~ n e a s u n d atid dried for 4X hours.

Koot Inass at each growth stage for each sa~iiplewas

determined.

3.3.6 Root L e n r t l ~Density Root length density is the ratio of the root length in the sa~nplingarea to the soil volu~nein that area. Root length density was calculated during 50% flowering and harvest stages where coring was used.

B)

Aboveground Portion

A sa~nplingarea of 0.75 ~ n ' ( 2 rows x 0.5

m) per plot was considered

during each sample. Sa~npleswere take11 at five growth stages, at nodal root initiation, panicle initiation, panicle develop~iient( 5 WAE), 50% flowering and at harvest stages. Plant number in the satnpling area was deter~iiined. Plants were tra~isported to the I:lb, separated into leaf blades, stems, leaf sheaths and reproductive parts. The parilmetzrs recorded for aboveground portin11 were:

Platit height of different s;~~iiples ; ~ each t growth htage was ~iicasuredfor ; ~ l l gznotypec. 'l'hc pl:!!!! !!eiglit w;~s~neasuredfro111the bdse of the p!z!it to the !ip of the filial leaf.

Total green leaf nu~ilberwas deter~iiinedat a11 growth stages except harvest t~~ne. 3.3.9 Leaf Area

From the destructive aa~nples at each growth stage, leaf blades were separated, cleaned and leaf area determined At nodal root initiation and panicle initiation leaf area was measured on the whole satnple. At panicle develop~ne~lt and 50% flowering, a subsample of 113rd total fresh leaf weight was measured. Leaf

31 area at harvest stage was not taken. Leaf area was determined using an LI- COR LI 3100 leaf area meter. 3.3.10 Leaf Drv Weiel~t

Leaf blades were transferred to an oven nt 80°C till constant weight was obtained. Leaf dry weiglits were recorded ;it each sample for different growth stages.

3.3.11 Stern I)rv Weiglrt For e;c11 s;itnple ; ~ t e;lch growtli stdge, ste~nsand leaf slieaths were tri~naferredto

; I I ~ oven

at 80°C; till constant dry weight wi~sobtained. Dry weights

for the four genotypec were recorded.

3.3.12 Shoot llrv Weicllt

The co~nbineddry weights of stems, peduncles and leaves were considered to constitute the shoot dry wciglirs for each genotype at each sample during different growth stages. 3.3.13 Total Plant 1)rv W e i c l ~ t Shoot dry weights, panicles dry weights and root dry weights were sulnmed to constitute total plant dry weight for each genotype at different sa~nplesduring different growth stages.

3.3.14 Root/shoot Ratio

The proportion of root weight to shoot weight was calculated to constitute root/shoat retio for all samples at different growth stages.

3.3.15 Stover 1)rv Weight

The genotypes were evaluated to their ability to prodi~cc.stover

;I[

harvest

stage. The shoot ;ind panicle dry weight? ~iiinusseed dry weight gnvr an estimate to the stover dry weight.

3.3.16 Iiitr~n;~ss The su111of the shoot, arid panicle dry weights ;at harvest g;we an estimate to total aboveground bioma~s.

3.3.17

Yieltl and Yield Cumyonents

The final sa~nplewith at1 area of 250 crn length of two rows zach 75 cm spacing (2.5 x 1.5 ~ n was ) harvested. The number of plants harvested were counted, panicles separated and oven dried at 80°C till a constant weight was obtained. The following yield parameters were ~neiisured:

1)

Panicle length

2)

Grain number per panicle

3)

Panicle weight

4)

100 seed weight

33 After oven drying, heads were threshed manually and yield determined.

3.3.18 Harvest Index (HI1

The proporlion of biological yield transferable to econoliic yield is the HI. It is worth mentio~iingthat the underground and aboveground portions were not significant with respect to tlle following parameters, and their probabilities were ~ i o tgiven in the ati;ilysis of variance table, thehe we1.e:

3.4

i)

Sets

ii)

Irrig;~tionx hers

iii)

Set I VS set 2

iv)

Ivig3tion x ket I VS set 2

V)

Genotypex xet I VS set 2

vi)

11rig;ltioll x genotype x set I VS set 2

NUTRIENT ANAI.YSIS The analysis of nutrient was carried out at two growth stages, at 50%

flowering 2nd at harvest stages. At 50% flowering, !e;lves, stetns and panicles were [nixed grounded together. At harvest, the nutrient an;llysis was carried out for both seed and the rest of the plant. The following observations were recorded at each

3.5

1)

Percent nitrogen and phosphorous.

2)

Total nitrogen and phosphorous in the plant.

WA'PEK USE AND WA'PER USE EFFICIENCY

The mount of water used to ;I deptli of 100 cln ns well ah the efficiency of using \v;lter ; ~ tri~clli11igati011l r ~ r lW;I\ ~iilcul;lted. The etll~;ltionused for the cnlculatiori WLS:

E'l' = Cliange in soil water content t Irrigation

t

-

Rainfall - 1)rainage Runoff

The dlni11;lge n11d run off wcre ;~ssu~iled to be nil tluling the rohi he;~so~i. Where El' s~alliisfor cv;~po[~anspirntion.

CHAPTER 1V

RESU1,TS

4.1 CLIMATE The ~neteorologicaltlatn durit~gthc experitnetit:tl period at ICRISA'I' Center :Ire shown as Appendix I . Tot;ll r;litlfall during the period was 100.6 tnln. The maximum was received during week 46 coilicidinp with the growth stages of panicle develop~nclitand 50% I'lowerit~g.The crop was given n o irrigation other than the trcarmetit.; under htu~ly.

The daily tiiaximu~iiand mitiimu~iiattiiuspheric te~iipcraturc.;were recorded for all the week\ of the experiii1ent;ll period (Fig. I and Appendix I). 111atltlitioti to this ttlso the air tetnper;~tore;ttid the soil tempcrutura (2 illid 5 C I I ~soil depth) was monitored duritlg the life cycle of the crop (Fig. 2 atid Appericlix 2).

4.2 UNDER(;ROUNI) PORTION

4.2.1

Nodal Roo$, Total Root Length and Total Root Mass Per Plant Ilurint: the Seoson

At the end of the growing season, the irrigation seedling treattnentc were significantly different with respect to nodal roots, total root length and total root tnass per plant (Table 1, Fig. 3,5,7).Genotypes were also significantly different for the root variables measured, but the differences atnong genotypes differed for

Standard weeks

Fig. 1. Temperature (Max, and

in.'^) and rainfall (mm)

during the growing season

Contramdepth)

20 rnm.[2c-!

Fig. 2a. Soil temperature

20 '4243

depth)

45 rnrn,(Z,c,m depth)

(k ) at 2 cm soil depth

4h 4'5 4'6 47 4'8 49 50 5;

5; i

2 3 4

Standard Weeks Control(5cmdepth)

20 rnm.[5-cy? depth)

Fig. 2b. Soil temperature

45 mrn,l5,~m,deplh)

(k) at 5 cm soil depth

6

Table I.

Analjsis of varience table i h a a i n p degrees o l lrcedonl (UP), F-l'robability (F-PK) l o r nodal rrwt number per plant (NHPl."), total root lengtl~per plant (TRI.PI:') and total root mass per plant (TRhII'I:').

Source v i V:ui:aio~~

S:~~nplcK 1nig:tlion

NRPL'

TICLPL'

TRMPL'

3

XXX

XXX

XXX

2

XX

X

X

XYX

IXX

b

ST1 VS ST2

I

Genolypc.;

3

S:1111plc x S'TI VS ST?

3

I ~ r ~ g ; i t nx ~STI n VS ST2

2

S:IIII[I~~

gcnolypc

J

lr,,g~,lIlypc

i

Irrlg.~lionST1 VS S'rL

2

ilrlg, x ticno

h

ST1 VS ST2 X i ~ . , ,: ~ srl .

rxx

(ic~~i,

vs ST? Y I;CI,O

Nu1 ? ~ ~ I I I ~ I ~ I C ~ I I I I P< I:.iXIi

1

P.l'l< a1 5111 kl..

HAI
y~,!::lll 1;1tI1e1 Ill,!!! !!c!

1C)llt

\~~>:cll1,

L,e.tf arra (c~it') ;atid leiit 111111iberpel plant

~ I ~ C I C ; I \ C ~rapidly

during tlic

\ca\on reaching tl~ei!irinxi~lium~nagtiitudebetween panicle ilcvelopment ;!ltd 50% flowering \!dyes.

A t 50% tlowerilig ataye, leaf area and l e ; ~ ftiumber per plant

decreased due to selicsceltce (Table 5 ) . (itnotypes were \ignificantly different ;it ~ i o d a root l initii~tionfor leaf area and leaf ~tulnber,and at panicle develuptneilt for leaf number only. The irrigation heedling treatments were only significant at 50% flowering for leaf area (Table 5 ) .

Tdble 5,

hlenn let11area and Ie;~fn u n ~ b r as r a funrlion a1 irrii(.~lion \cedlinl: 1re;llmesfs and eena~~pec.

NRI

L 1:L L , ~i,xc:1 LN: Lc;~fn11111hci

I'I

PND

il'll.

Nil1

1'1

I'ND

illtL~l'I

111

il?

111

0114

'I?

711

7.7

1.6

JS

hX

l1l.l

'Ill 00

i(5

71)

1115

1X

,

Ill1

'JI

i11

7 li

XX

I;III~ t liei~ht,pi1111cIcIcII:~II, II~;IS\~

I00 e t ~ 1 1

yiclci, \to\,ct w c ~ g l ~I~~oIII,I~\, t, ;III~ II,II~VC>~III(ICX (Talll~,71. 111 II~II~JC~~,

\1?5-1 wit11 ;I t i ~ , ~ ~ i ~ ryirlcl n i i n 1 1 i 3.25 T l l i ; ~wlicrc c ~ f1.56 T/ll,i (1.1~. 20). ll index (HI1 of f ~ ~ u~csoljpcr. r

PLli

I'NL.

(~111)

(~$11)

E3h.l

I56

!I!

L;I:ldi

I54

X.Ll

hlli-l

212

N1g.1 ~lllll:

14s

Gcnil.

'

Ill

liN1 Shl (p)

Y~rl~l (T~I;I)

S'IO\YI'

RIO

('I'~I,I)

(rn~.~!

IOYh

l.hIl

I

J.4tl

742

ll.dll

l I I4

iJ1X

?.AX

.$.I)?

7 30

0.14

18.5

I IX?

3 6')

125

5

X.XII

1) I 7

22.2

IiIX

245

I.ih

1.75

,311

1147

CiRNPN

PLH

(iHNI'N1

(~111)

I

(ilINI1N

iillll

I'LH ICIlll

(;Iletit.;. The per c c ~ i t\ntl moi\ture for irtigiitioli tre;1tliienrs : ~ t0-50 nil 50-100 cln \oil deplli uel.e \ i g l i i f ~ c , ~ ;a~t i ~t ; r r I y91:lgcl; (Fig. 30).

M o \ t ot tlic ~lullielrtII.I!:I!K!~~\ w r l e ]lot \iplrific;~~lt!ytliffcrc~!! t: 50'7~ ilnfic111ig or

;I!

Iia~?c\t ~IU\\III \tCigrl; (''1t)Ic

I 0 ;r]i(i I I), 'Sli~s~ i i ~ 111ipIy ry tliitt ~ l i c

irtigotio~iIevelh had 11o r i g ~ i i f i c d ~ilnp;ict it r ~ tliutrlellt i absorpric~t!:I!!!! !lie dilfcrc~iceh between getlotype5 wcrc due ~ i i ; ~ i ~toi l ydiffercncc.; betwee11tlie irrig;rtin~i scetllilig trent~ne~lts ;!lid liot l o differelices ill ~ i i ~ t r i e t;~v;~ilability lt tn ~ h cgeliolypes.

\

24

SE(*)

-.g ??

2.3

X"',"

22

3 +d 0 .-

20

E .-

18

SEjt)

SE(*)

0 75

2.4 ............... I,..,

0 48

.x - - - - - - - - - -

:...

0

('(. i i c l ll '~; ~ pi gc.r ~ ) s e ~(~I i~i ~i ti ~ di p the \yiii))~i\iiitiiti11L~I~.II\, I~itcr~i;itio~i;il I'l~itit l1liysioIogy ('o~~grtsL;,1:cL~. 15. 20, IOXX. N e w [lellii, l ~ i t c r t ~ i ~ r ('ii~ph i o ~ i ~ ~Rchra~cli l 11iht1111te for tlie S e ~ i i i A i i i i 'l'rci]iic~, l ' s i t ; ~ ~ i c l i ei111dli1:i r ~ ~ , l'r,t[ie\li S(l2 324 II~~I;I,

S ~ c t / i ; ~ ~ iN~ iittirl i i ~ iS i i ~ g l iS ( O ~ ~ l ) i i l i l i \ l i c ~I('I. . ..

..

- - ~ ~ - -- - - - - . . - - - - - - . . - - -

-

10.3

.!'i .I, .; i , 1,

.: ' .

i

.,, . !I

.'.. R ! I ,

(2

: . t j

..I 't,,

i '

'C. 1

3.0

41.,3

!

0.0 0.9

40.:

! :

1.)

*1'4.2 5!.': 14.;

3 1

2.')

2q.2

.

1 " H I ' 1 '

I

!

I n .

, ,

1 ,i: 3

! I r '

'I 2

I