113. Growth and Seed Yield of Lentils Genotypes

CSIRO PUBLISHINGwww.publish.csiro.au/journals/ajar Australian Journal of Agricultural Research, 2005, 56, 971981

Growth and seed yield of lentil (Lens culinaris Medikus) genotypesof West Asian and South Asian origin and crossbreds between

the two under rainfed conditions in Nepal

R. ShresthaA,B,D, K. H. M. SiddiqueA, N. C. TurnerA,C, D. W. TurnerB, and J. D. BergerA

ACentre for Legumes in Mediterranean Agriculture (CLIMA), Faculty of Natural and Agricultural Sciences,The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.

BSchool of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia,35 Stirling Highway, Crawley, WA 6009, Australia.

CCSIRO, Plant Industry, Private Bag No. 5, Wembley, WA 6913, Australia.DCorresponding author. Email: renuka [email protected]

Abstract. Nineteen diverse lentil genotypes, 8 originating from South Asia, 6 from West Asia, and 5 crossbredsusing parents from South Asia and West Asia (or other Mediterranean environments), were evaluated for growth,phenology, yield, and yield components at Khumaltar in the mid-hill region of Nepal. Additionally, dry matterproduction, partitioning, root growth and water use of 8 selected genotypes from the 3 groups were measured atkey phenological stages. The seed yield of the West Asian genotypes was only 330 kg/ha, whereas the South Asiangenotypes produced amean seed yield of 1270 kg/ha. The crossbreds had a signicantly (P= 0.05) greater seed yield(1550 kg/ha) than the South Asian genotypes. The high seed yield of both the South Asian and crossbred genotypeswas associated with rapid ground cover, early owering and maturity, a long reproductive period, a greater numberof seeds and pods, high total dry matter, greater harvest index, and high water use efciency. West Asian genotypes,on the other hand, owered 43 days later, matured 15 days later, and had a shorter reproductive period (by 22 days)than the crossbred and South Asian genotypes. The 23% greater seed yield in the crossbreds compared with theSouth Asian genotypes was the result of a similar increase in seed size (weight per seed).

There were no signicant differences in total root length (mean 4.7 km/m2), root dry matter (mean 95.5 g/m2),or water use among the 3 groups during the major part of the growing period. There was a signicant differencein total water use due to the longer growing season of the West Asian genotype ILL 7983 and its ability to uselate-season rainfall. Maximum water use efciencies for seed yield of 7.0 kg/ha.mm and for above-ground drymatter of 18.9 kg/ha.mm were comparable with those reported in India and the Mediterranean environments ofsouth-western Australia and Syria.

Additional keywords: genetic variation, photoperiodic sensitivity, earliness, pilosae, residual soil water.

IntroductionLentil (Lens culinaris Medikus) is the most importantgrain legume in Nepal. Although initially only cultivatedon the plains (terai) of southern Nepal, recently lentilshave gained popularity in the hill and mountain regionsof Nepal, where it now contributes 5% of the countrysarea and production of lentil (ABPSD 2004). Lentil isgrown during the winter growing period (OctoberMarch)as a post-rainy season crop. It is usually grownin rotation with rice (Oryza sativa L.) and/or as amixed crop with wheat (Triticum aestivum L.), barley(Hordeum vulgare L.), mustard (Brassica juncea L.), linseed(Linum usitatissimum L.), grasspea (Lathyrus sativus L.), oreld pea (Pisum sativumL.). Lentil is sown into thewet paddy

before the rice is harvested (the utera or relay system) orimmediately after the rice has been harvested and the soilcultivated (the paira or post-rice system). In both croppingsystems, lentil depends predominantly on residual soil waterfrom the preceding rainy-season crop for its growth anddevelopment. Soilwater decit during crop establishment andin the post-owering period is the major constraint affectingproductivity of the crop. The large year-to-year variabilityin winter (OctoberJanuary) rainfall from 11 to 204mm hasled to highly variable seed yields of 220 to 1800 kg/ha inexperimental plots (Shrestha 1997, 1998).

The lentils currently grown in Nepal are the small-seeded pilosae type of landraces belonging to the subspeciesmicrosperma (Bahl et al. 1991) that have limited genetic

CSIRO 2005 10.1071/AR05050 0004-9409/05/090971

972 Australian Journal of Agricultural Research R. Shrestha et al.

variation (Erskine 1985; Erskine and Saxena 1991; Erskineet al. 1998). In Nepal, lentil improvement activity beganin 1977, but the systematic genetic improvement of lentilbegan only in 1985 with the establishment of the NationalGrain Legume Research Program (NGLRP) (Bharati andNeupane 1991). Systematic evaluation of the local landracesand introductions from neighbouring countries (India,Bangladesh, Pakistan) and the International Center forAgricultural Research in Dry Areas (ICARDA), Syria, beganin 1985. However, none of the direct introductions of large-seeded West Asian genotypes has performed well. UnderNepalese conditions these West Asian genotypes owerwhen the South Asian genotypes are maturing, suggestingthat photoperiod or vernalisation requirements limit theadaptation of germplasm from the Mediterranean region(Sinha 1977; Erskine and Hawtin 1983; Summereld et al.1984, 1985; Erskine 1997). In 1981, ICARDA initiatedan extensive crossing program of small-seeded pilosaelentils from South Asia with germplasm from other regions,particularly large-seeded germplasm from West Asia andEthiopia, to widen the genetic diversity in South Asianlentils (Erskine and Hawtin 1983; Erskine et al. 1998). Theincorporation of desirable traits, particularly early owering,from the South Asian landraces into the large-seededMediterranean germplasm through hybridisation and directintroduction from other short-day growing environments(cv. Precoz, Argentina) has provided an opportunity to selectlentil genotypes with improved seed size and higher yield(Erskine 1983).

Since the establishment of the NGLRP in Nepal, severalexotic germplasms including both small and large-seededtypes were introduced from ICARDA and tested undervarious agro-ecological zones (Bharati and Neupane 1991).It was only during the early 1990s that the introduction andeld evaluation of genotypes from ICARDA that were bredfor targetted environments of South Asia, led to identicationof a number of promising genotypes (Shrestha 1996, 1997;Shrestha and Neupane 2000). Furthermore, recent studies inNepal have also shown the superior performance of thesegenotypes in terms of seed yield and disease resistance underboth the post-rice and rice relay system (Francis and Siddique2001; CLIMA 2005). However, to date no systematic studieswith regard to phenology, drymatter production/partitioning,water use, and root growth of lentils have been conductedin Nepal, particularly with the newly developed crossbredsbetween the South Asian and West Asian (or Mediterranean)genotypes. Hence, a subset of the promising genotypesfrom the Nepal lentil improvement program, including thelarge-seeded types from ICARDA and the standard localcultivars, was selected for detailed studies under a rainfedenvironment. The main objective of the study was to evaluatethe genotypic variation in the adaptation of a range oflentil germplasms originating from South Asia, West Asia(or from Mediterranean-type environments), and crossbreds

between the 2 sources, and to identify the morphological andphenological traits associated with high dry matter and seedyield under the rainfed environment of the mid-hills regionof Nepal. We hypothesise that there will be more variation intermsof phenology, cropdevelopment and seedyield betweenlentil groups (West Asia, South Asia, and crossbreds) thanwithin groups.

Materials and methodsSite description

A eld experiment was conducted during the 200102 seasonat Khumaltar (85.20E, 27.40N; 1360m above sea level) in theKathmandu Valley, Nepal. The Kathmandu Valley is representative ofthe warm temperate mid-hill region of Nepal.

The soil in Khumaltar is a deep, silt loam to silt clay loam developedon depositional alluvial terraces (Sherchan 1997). It contains 1.9%organic matter (OM) with a pH of 4.3 and bulk density of 1.3 g/cm3

and 1.7 g/cm3 at 015 cm and 1560 cm soil depth, respectively. Thesoil texture is 16% sand, 62% silt, and 22% clay, with 0.09% nitrogen(N), 27.4mg phosphorus (P)/kg, and 85.0mg potassium (K)/kg. Soilanalyses were done by the Soil Science Division, Khumaltar, Nepal,using the hydrometer method and USDA textural classication forsoil textural classes, pH in 1 : 1 soil : water (Jackson 1958), OM bythe Walkley-Black method (Hesse 1972), total N by the Kjeldahlmethod (Hesse 1972), available P by the Olsen method (Olsen et al.1954), and exchangeable K by using an ammonium acetate extractant(ADAS 1981).

Maximum and minimum temperatures, rainfall, and Class A panevaporation at the experimental site were recorded daily at 0845 hoursand 1745 hours during the experiment. Pan evaporation data were notavailable for the period SeptemberNovember.

Genotypes and agronomic practices

Nineteen lentil genotypes, 8 locally adapted landraces from South Asia,6 from West Asia, and 5 crossbreds (where one of the parents wasfrom South Asia and the other from West Asia or from Mediterranean-type environments), were grown in a completely randomised blockdesign with 4 replicates (Table 1). Each plot was 5.5m long and4m wide (16 rows). The row spacing was 25 cm and plant-to-plantspacing within a row was 25 cm. Border rows were maintained atboth ends of each block and border strips, 0.5m on either side of theplots, were excluded from the measurements. Before sowing, the landwas ploughed, harrowed, and levelled. The previous crop was soybean(Glycine max L.).

Seeds were hand-sown at a depth of 35 cm on 21 October at adensity of 200 plants/m2. Seeds were treated with Bavistin fungicide(2 g/kg seed). Rhizobium inoculum (Rhizobium leguminosarum) wasmixed with moist soil and sprinkled over the rows. At sowing,20 kgN/ha (diammonium phosphate: 18% N, urea: 46% N), 40 kg P/ha(diammonium phosphate: 20% P), and 20 kg K/ha (potassium chloride:50% K) were applied. Carbofuran 3% CG insecticide was broadcast at2 kg/ha at sowing. Seedlings began to emerge 6 days after sowing (DAS)and reached 7590% emergence at 810 DAS. Crops were harvestedfrom 25 March to 24 April. The net area for harvest was 3.0m by 2.5m(12 rows of 2.5m length).

Seedling establishment

Plant number was counted 28 DAS, and at maturity, using a 1-m lengthof row at 4 random positions, and at dry matter harvests throughout theseason, using 2 quadrats of 0.5m by 0.5m per plot.

Adaptation of diverse lentil genotypes in the mid-hills of Nepal Australian Journal of Agricultural Research 973

Table 1. Lentil genotypes used in the study, their seed weight (g/100 seeds) at sowing, origin, and pedigreeILL, International Legume Lentil; FLIP, Food Legume Improvement Program

Accession number Cultivar name Seed Group Origin Pedigreeweight

ILL 7957 (FLIP96-25L) 3.5 West Asia ICARDA ILL 5883 (Syria) ILL 6246 (Syria)ILL 7978 (FLIP96-46L) 4.3 West Asia ICARDA 91S 82379ILL 7983 (FLIP96-51L) 2.3 West Asia ICARDA 91S 88607ILL 8006A 3.9 West Asia ICARDA Not knownILL 8621 (FLIP2002-20L) 3.6 West Asia ICARDA ILL 5883 (Syria) ILL 7149 (Syria)ILL 8633 (FLIP2001-12L) 3.0 West Asia ICARDA ILL 5883 (Syria) ILL 7005 (Syria)ILL 3512 (LG 7) Simal 1.6 South Asia India LandraceILL 2573 (PL 639) Khajura 2 1.7 South Asia India L 9-12T8ILL 2580 (L 1278) Shital 1.6 South Asia India LandraceILL 7346 (LG 198) Khajura 1 2.0 South Asia India LandraceILL 7200B (FLIP92-35L) 1.7 South Asia ICARDA Not knownILL 4402 1.7 South Asia Pakistan LandraceILL 7723 2.7 South Asia Pakistan 89503, landraceILL 8010 Sindur 1.6 South Asia Nepal Landrace

ILL 6829 (FLIP89-71L) 1.9 CrossbredA ICARDA ILL 4407 (Pakistan) ILL 4605 (Argentina)ILL 7537R (FLIP93-36L) 2.2 CrossbredA ICARDA 90S 30799ILL 7979 (FLIP96-47L) 2.4 CrossbredA ICARDA 91S 87270ILL 7982 (FLIP96-50L) 2.1 CrossbredA ICARDA 91S 88526ILL 7986 (FLIP96-54L) 2.9 CrossbredA ICARDA ILL 5748 (Syria) ILL 2578 (India)ACrosses between genotypes from South Asia and West Asia (or other Mediterranean-type environments).

Phenology and growth parameters

Times from sowing to 50% owering (at least 1 fully open owerin 50% of the plants), rst pod (50% of plants with their rst podvisible), last ower (90% of the plants with no owers), 50% podding(50% of pods in a plot turned yellow), and physiological maturity(90% of plants in a plot turned golden brownwith fully lled pods) wererecorded on a whole-plot basis. Flowering and pod lling durationswere calculated as time from 50% owering to days to last owering,and time from rst podding to maturity, respectively. The reproductivegrowth period was dened as the duration from 50% owering tophysiological maturity.

At physiological maturity, 10 plants were selected at random fromthe harvest area to measure plant height and primary branch number(branches subtending from the main stem), number of pods, and seedsper plant. Plant height wasmeasured from ground level to the last visiblenode on the main stem (just below the apical bud).

Morphological characters

Assessment of leaf morphology and seed coat colour was madeaccording to the International Board for Plant Genetic Resources(IBPGR 1985). Stem pigmentation was recorded at 44 DAS, leaf colourat 44 and 116 DAS, and leaet size at 104 DAS. Leaf hair density wasestimated using a magnifying glass at 116 DAS.

Ground cover

Ground cover was recorded at the vegetative, owering, and poddingstages. The proportion of ground area (%) covered by the crop canopywas estimated visually between 1000 and 1300 hours (4 estimatesper plot).

Dry matter production and partitioning

Above-ground dry matter was measured at 58 DAS (vegetative),50% owering, 50% podding, and maturity. Plants were cut at thebase from a 0.25-m2 area (0.5m by 0.5m quadrat) at 2 positions

per plot. Plant samples were oven-dried at 70C for 48 h beforeweighing. Senescent and fallen leaveswere collected and included in thedry weight.

Five plants were sampled and separated into leaves, stems, owers,and pods. Projected green areawasmeasured using aSystronics leaf areameter (Model 211, Naroda, Ahmedabad, India). Green area included thearea of leaves, stems, and pods. Plant samples were then oven-dried at70C to a constant weight.

Yield and yield components

At maturity, plants were harvested by cutting stems at ground level.Seeds were separated from the straw by hand-threshing. The straw(leaves, stems, and podwalls)was oven-dried at 70C to constantweight.Two to four sun-dried, pre-weighed subsamples of seed, each weighingabout 100200 g, were oven-dried at 70C for 48 h to estimate the seedyield on an oven-dry basis. Five hundred seeds were counted, oven-dried at 70C for 48 h, and weighed to measure seed size (expressed as100-seed weight). Harvest index (HI) was calculated as the proportionof seed weight to the total above-ground dry matter.

Soil water content

Soil water content from 0 to 60 cm depth was measured gravimetricallyin 10-cm sections of a 50-mm-diameter soil core. Measurements weremade before sowing, at 58 DAS (vegetative stage), 50% owering, 50%podding, physiological maturity, and immediately after the nal cropharvest. One sample (1 core) per plot was taken before sowing, and thesubsequent samplings (after crop establishment) consisted of 2 cores,one centered over the cut stems of plants within a row and the otherbetween the rows at 12.5 cm from the lentil plants. All the genotypes(4 replicates) were sampled for soil water content before sowing and atharvest, and the soil sampling at different growth stages was done in7 contrasting lentil genotypes, 2 from West Asia (accessions ILL 7978,ILL 7983), 3 from South Asia (cvv. Simal, Khajura 2, and Sindur) and2 crossbreds (accessions ILL 7979, ILL 7982).


The fresh soil samples were weighed and subsequently oven-driedat 100C to constant weight. Volumetric water content was calculatedusing the measured bulk density for the corresponding soil depth. Meansoil water content was obtained from within-row and between-rowmeasurements. Bulk density was measured down to 60 cm depth, at15-cm intervals using a core size of 7.1 cm height and 7.5 cm diameter(2 samples per depth).

Crop water use is the water transpired by the plants plus waterlost via soil evaporation (evapotranspiration). Total crop water use wasdetermined by summing the change in water content in the soil between0 and 60 cm over the period considered, and the rainfall. Drainage andrun-off were assumed to be negligible, a reasonable assumption in thisseason. Water-use efciencies were calculated as the ratios of above-ground dry matter (WUEDM) or seed yield (WUEgrain) to total cropwater use from sowing to nal harvest.

Root length and dry matter

Rootswere sampled at the same time as the above-ground drymatter andsoil water contents. Root measurements were made on the same 7 lentilgenotypes as sampled for water use. Root sampling was limited to theinner 12 rows. Root samples were collected in 10-cm increments to themaximum depth below which no more roots were visible. Roots weresampled using a 50-mm-diameter tube auger. One sample consisted of2 cores, 1 core centered over the cut stems of the plants and the othercore at 12.5 cm from the lentil plants.

The soil samples with intact roots were then soaked in Calgon(sodiumhexametaphosphate/0.1% sodium tri-polyphosphate) overnightto disperse the clay, and rootswerewashed free of soil over a 1-mmsieve.Dead (black) roots were removed. Root length was estimated using themodied line intersectmethod as described byTennant (1975). The rootswere then oven-dried at 70C for 48 h and weighed. Total root lengthper unit area of land (km/m2) was calculated by totalling root lengthdensity (cm/cm3) to the measured depth.

Data analysis

Dry matter, seed yield, and yield components were analysed usingone-way ANOVA and linear mixed models [for estimating variancecomponents by the method of residual or restricted maximumlikelihood (REML)], with genotypes nested within origin or group(West Asia, South Asia, and crossbreds) in Genstat 6th edition (LawesAgricultural Trust, Rothamsted Experimental Station, Hempstead,Hert, UK). Random effect included genotypes within the group.Least signicant differences (l.s.d., P= 0.05) were calculated (Genstat2002). Morphological traits, expressed on a qualitative scale (highervalue indicating the higher intensity of the character), were analysedusing hierarchical cluster analysis in SPSS, version 11.5 (SPSSInc., Wacker Drive, Chicago, IL, USA) (SPSS 2002). Correlationcoefcients among various parameters were estimated using the Pearsoncorrelation (SPSS 2002).

Results

Weather

The mean monthly temperature in September was 23Cand reached the lowest mean temperature of 10.0C inJanuary (Fig. 1). The minimum temperature ranged from1.0 to 1.4C from the third week of December to thesecond week of January and temperatures slowly increasedfrom February onwards. Mean daily evaporation (class Apan) ranged from 1.5mm/day (January) to 3.4mm/day(April). The rainfall during the autumn months of Septemberand October was 158mm, followed by a period without rain

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from November to mid-January. Rainfall of 159mm wasrecorded from the second week of January to the rst week ofApril (86164DAS), coincidingwith increasing evaporation.The rainfall from January to April was 112% higher than thelong-term average for the same period. The 87mm of rainfallreceived after 147DASmay have been too late to benet yieldin the early-maturing genotypes.

Seedling establishment and canopy development

The initial number of plants at 28 DAS (160164/m2) didnot vary among groups or genotypes within groups andthe mean emergence was 82% of total seed sown. Plantnumbers declined after podding due to death by vascularwilt (Fusarium oxysporum f. sp. lentis), particularly inthe large-seeded genotypes. Plant numbers ranged from80151 plants/m2 among lentil genotypes at harvest, witha 19% lower stand (compared with the initial stand) in theWest Asian genotypes compared with 1% in the South Asianand crossbred genotypes.

At 58 DAS (vegetative phase), the percentage groundcover differed signicantly among groups (P< 0.001), butnot within groups: South Asian and crossbred lentils had25% greater ground cover than West Asian lentils (Fig. 2).Ground cover increased to a maximum of 87% at owering(133 DAS) for West Asian genotypes, compared with 97% atpodding (154DAS) for SouthAsian and crossbred genotypes.


Days after sowing25 50 75 100 125 150 175

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Fig. 2. Percent ground cover of lentil genotypes from West Asia (),South Asia (), and crossbreds (N ), measured at differentgrowth phases. Fitted curves for genotypes from West Asia (),South Asia (. . .), and crossbreds ( ).

An erect plant type, low plant density, and fewer branchnumbers in the West Asian genotypes (except ILL 7983)contributed to the lower canopy cover than in the South Asianand crossbred genotypes (data not presented).

Morphology and phenology

Morphologically, the crossbred genotypes were similar tothe South Asian genotypes in terms of leaf and stempigmentation, testa pattern (speckled) and cotyledon colour(red), whereas the leaet size, colour, and pubescence densityof the crossbreds were intermediate between the South Asianand West Asian genotypes (data not shown).

In the Kathmandu Valley, the South Asian and crossbredlentils reached 50% owering in mid-January when thephotoperiod was 10.6 h (1200 degree days). This occurredabout 1.5months earlier than for theWest Asian genotypes inearly March, which owered when the daylength was 11.6 h(1700 degree days). The West Asian genotypes were alsoconsiderably later to pod andmature than the SouthAsian andcrossbred genotypes (Fig. 3). The nested ANOVA revealedsignicant differences between both groups and genotypeswithin groups in the time to 50% owering, 50% podding,maturity, and the reproductive growth period. However,REML demonstrated that variance components for thesetraits were 37 times higher between groups comparedwith genotypes within groups. The late owering of theWest Asian genotypes was also associated with a shortowering duration (mean 30 days) and pod lling duration(mean 33 days) compared with the mean duration of 58 days

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ILL 7986ILL 7982ILL 7979

ILL 7537RILL 6829

SindurILL 7723ILL 4402

ILL 7200BKhajura 1ILL 2580

Khajura 2Simal

ILL 8633ILL 8621

ILL 8006AILL 7983ILL 7978ILL 7957

FloweringSowing Podding Maturity

West Asia

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Fig. 3. Duration from sowing to 50% owering (solid bars), rstpod (open bars), and physiological maturity (grey bars), for 19 lentilgenotypes.

and 40 days, respectively, in the South Asian and crossbredgenotypes (data not presented). There were no signicantdifferences in phenology between the crossbreds and theSouth Asian genotypes.

Green area index (GAI), dry matter production,and partitioning

There were no differences in GAI at the vegetative phase(58 DAS) but group differences emerged throughout thegrowing season. The West Asian genotypes had the highestGAI (4.1) at 133 DAS, whereas the South Asian genotypesattained the maximum GAI (3.5) at podding (154 DAS)(Fig. 4a).

Total above-ground dry matter at maturity differedsignicantly between groups (P< 0.001) and betweengenotypes within groups (P= 0.003), with 83% of thevariance explained by the groups. At maturity the highestdry matter was recorded in the crossbreds, followed by theSouth Asian genotypes, but the West Asian genotypes hada 3540% lower dry matter at maturity than South Asiangenotypes and crossbreds (Fig. 4b). As a result, theSouth Asian and crossbred genotypes had double the averagerate of dry matter accumulation at 4.2 g/day compared withthe West Asian genotypes at 2.2 g/day.

There was signicant variation in the partitioning of drymatter (Fig. 5), particularly between groups (6494% ofvariance in dry matter components for leaf, stem, seed, andpod wall). At the vegetative stage (58 DAS), leaf dry matterwas 70% of the total, but decreased to 20% in the SouthAsian and crossbred genotypes and 27% in the West Asiangenotypes by maturity. At maturity, the pod wall accountedfor about 19% of total dry matter in the South Asian and thecrossbred genotypes, signicantly higher than theWest Asian


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Fig. 4. (a) Green area index; (b) total above-ground drymatter; (c) root-to-shoot ratiofor lentil genotypes from West Asia (circles), South Asia (squares), and crossbreds(triangles); and (d) cumulative water use (060 cm soil depth) in genotypes fromWest Asia: ILL 7983 (), crossbred: ILL 7979 (N ), and South Asia: Simal () andKhajura 2 () during the growing period. Bars indicate standard errors.

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Fig. 5. Drymatter partitioning of 3 representative lentil genotypes from (a)West Asia, (b) SouthAsia, and (c) crossbreds.Legends: leaf (no ll), stem (hatched), pod wall (grey), and seed (black).

genotypes (14%). The crossbreds had the highest dry matterin the seeds (36%) at maturity, followed by the South Asiangenotypes (30%) and then the West Asian genotypes (14%).The ratio of leaf to stem dry matter in the crossbred andSouth Asian groups was 19% higher than in the West Asiangroup; however, variation within groups was 3 times greaterthan between groups. The crossbreds had a signicantly

(P< 0.001) higher ratio of seed to pod dry matter than theWest Asian and the South Asian group, and this ratio was theleast in the West Asian group.

Root growth

Lentil groups and genotypes within groups did not differsignicantly in total root dry matter (75.7128.6 g/m2) or


total root length (3.95.6 km/m2). There was an increase intotal root dry matter up to about 130 DAS and an increasein root length to about 150 DAS, followed by a decrease tomaturity caused by root death (data not shown).

There was a signicant variation among groups in root-to-shoot ratio (5097% of variance) during the growing season,with the highest values recorded in West Asian material(Fig. 4c). There was a dramatic decrease in the root-to-shootratio in all groups over the growing season from 2.03.3 at58 DAS to 0.160.38 at maturity. At maturity there wereno signicant differences among the groups in the root-to-shoot ratio.

Root length density, measured within the row,reected the root dry matter pattern. Root lengthdensity was greater in the top 10 cm than at deepersoil depths (Fig. 6) and decreased with increasing lateraldistance from the plants (data not presented). Varianceanalysis showed that root length density only variedsignicantly among the groups of genotypes at podding,when South Asian genotypes> crossbreds>West Asiangenotypes (Fig. 6).

Water use

There were no signicant differences in water use amongthe 3 groups of lentils during the major part of the growingseason (Fig. 4d). The total seasonal water use ranged from194mm in the early South Asian genotypes to 278mmin the long-season West Asian genotypes, because theWest Asian genotypes were able to use the late-seasonrainfall (Fig. 1).

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Fig. 6. Distribution of mean root length density (cm/cm3) withdepth measured within the row for lentil genotypes from West Asia:ILL 7978 (), ILL 7983 (); South Asia: Sindur (), Simal (); andcrossbreds: ILL 7982 (N ), ILL 7979 () at podding. Standard errorswere smaller than the symbols.

Growth, yield, and yield components

Seed yield varied from 130 to 1800 kg/ha among thegenotypes, with signicantly (P< 0.001) different meanseed yields of 1550 kg/ha, 1270 kg/ha, and 330 kg/hafor crossbreds, South Asian, and West Asian genotypes,respectively (Table 2). However, the mean straw yield(average 2400 kg/ha) did not vary signicantly among the3 groups. The HI varied signicantly between genotypesand groups, ranging from 0.08 to 0.41, with mean valuesof 0.38, 0.33, and 0.14 for the crossbreds, South Asian, andWest Asian genotypes, respectively (Table 2).

The mean plant height at maturity (39 cm) was similar forthe 3 lentil groups. The South Asian and crossbred genotypesproduced 1 more primary branch/plant than the West Asiangenotypes, which had 4 branches/plant. The number oflled pods, seeds/plant, 100-seed weight, seed yield, andnal above-ground dry matter showed signicant differencesamong genotypes and groups (P< 0.001). The mean numberof pods/plant was 82, 91, and 41 in crossbreds, SouthAsian genotypes, and West Asian genotypes, respectively,and was signicantly different (P< 0.001) among groups.Genotypes from South Asia and the crossbreds had100120% more lled pods than the West Asian genotypesthat had much higher numbers of unlled pods. TheSouthAsian genotypes produced signicantly higher numberof seeds/plant (170) than the crossbreds (158), whereas theWest Asian genotypes produced the fewest seeds/plant (56).Hundred-seed weight was 1.62.2 g in crossbreds, 1.31.8 gin the South Asian genotypes, but 1.42.2 g in the WestAsian genotypes (Table 2). On average, the seed size in thecrossbredswas 22%higher (P= 0.05) than in theSouthAsiangenotypes. The mean seed size at nal harvest was 3861%smaller in the West Asian genotypes than their original seedsize at sowing, whereas the reductions were 333% and1328% in crossbreds and South Asian genotypes,respectively (Table 1). The mean seed size of West Asianand crossbred groups was signicantly (P< 0.001) greaterthan of the South Asian group; however, 64% of variation inseed size was within the group.

Using all 19 genotypes, seed yield was negativelycorrelated with time to owering (r=0.85**), time tomaturity (r=0.64**), and the number of unlled pods(r=0.66**), but positively correlated with the number oflledpods (r= 0.57**) and seeds (r= 0.61**), above-grounddry matter (r= 0.87**), and HI (r= 0.91**). Also, there wasa signicant positive correlation between number of pods andthe number of primary branches (r= 0.58**).

Water use efciency (WUE)

The mean WUE of 18.3 kg dry matter (DM)/ha.mmand 6.3 kg grain/ha.mm for selected genotypes fromSouth Asia and the crossbreds were signicantly higherthan the 9.6 kgDM/kg.mm and 1.9 grain/ha.mm for selected


Table 2. Seed yield, yield components, and water use efciencies (WUE) for dry matter (DM) and grain at maturity of lentilgenotypes grown at Khumaltar

Genotypes Pods/plant Seeds/plant 100-seed Seed yield Total dry HI WUEDM WUEgrainweight (kg/ha) matter (kg/ha.mm)(g) (kg/ha)

West AsiaILL 7957 37 40 1.95 242 2847 0.08 ILL 7978 58 84 2.21 435 1789 0.24 8.2 2.0ILL 7983 53 91 1.37 507 3057 0.16 11.0 1.8ILL 8006A 27 28 1.51 129 1659 0.08 ILL 8621 38 47 2.03 340 2673 0.12 ILL 8633 33 47 1.85 337 2631 0.13

South AsiaSimal 90 166 1.53 1440 4173 0.35 18.2 6.3Khajura 2 88 175 1.41 1220 3585 0.34 18.7 6.3ILL 2580 91 169 1.52 1351 3909 0.34 Khajura 1 96 175 1.35 1094 3452 0.32 ILL 7200B 112 220 1.43 1152 3612 0.31 ILL 4402 105 195 1.42 1346 4062 0.33 ILL 7723 68 129 1.82 1125 3762 0.30 Sindur 73 134 1.55 1392 4082 0.35 18.9 5.9

CrossbredsILL 6829 96 179 1.65 1715 4245 0.40 ILL 7537R 84 168 1.72 1795 4520 0.40 ILL 7979 86 163 1.72 1374 4270 0.32 18.5 5.9ILL 7982 88 186 1.82 1477 3640 0.41 17.2 7.0ILL 7986 54 95 2.24 1398 4036 0.35

P value


0

500

1000

1500

2000

2500

0

1500

3000

4500

6000(a) (b)

0 400300200100 0 400300200100Total water use (mm)

TDM

(kg/h

a)

Seed

yie

ld (k

g/ha)

Fig. 7. Relationship between (a) seed yield, and (b) above-ground dry matter and cumulative water usefor selected lentil genotypes fromWest Asia (), South Asia (), and crossbreds (N ). Lines are based onan intercept of 115mm and water use efciencies for (a) 15 ( ), 10 ( ), and 5 () kg grain/ha.mm,and (b) 40 kg/ha.mm total above-ground dry matter. Data also plotted from other studies in India ()(Yusuf et al. 1979; Sharma and Prasad 1984); Tel Hadya, Syria () (Zhang et al. 2000); Breda,Syria () (Silim et al. 1987, 1993); Jordon () (Badarneh and Ghawi 1994); andWestern Australia () (Siddique et al. 1998, 2001).

springearly summer, resulting in few lled pods, a largenumber of unlled pods, poor dry matter accumulation, andhence low HI and very poor seed yields. The implicationof this poor adaptation is that the limited genetic diversity inSouthAsian lentils will not be overcome by farmers passivelyadoptingWestAsian germplasmbecause there is no incentivefor them to do so. At present, only the early maturing, large-seeded cultivar Precoz (ILL 4605) is being used in the lentilbreeding programs in Nepal. Active steps are required in thelentil breeding program to widen the genetic base of releasedcultivars. These include a crossing programbased on articiallong-day conditions, or applying vernalisation so that a widerange of West Asian parental germplasm can be exploitedby breeders.

Indeed, our results conrm the importance of earlyphenology in breaking the South Asian bottleneck bycrossing with West Asian material (Erskine 1997). Wedemonstrate a yield advantage in the crossbred materialover local landraces and cultivars, which is associated withrapid growth, early owering, and early maturity from theSouth Asian parents, and seed size traits from theWest Asianparents. Moreover, the increase in seed size in crossbredmaterial makes it a more marketable proposition thanSouthAsian landraces and cultivars (Sharma et al. 1991), andthe fact that straw yield was not compromised is importantin regions such as Nepal where straw is a highly valued stockfeed. The total dry matter for the South Asian genotypesin this study was very similar to that under farmers elds(Maskey et al. 2001).

Large-seeded genotypes, particularly of West Asianorigin, were not adapted in Nepal because of theirphotoperiod sensitivity, and also greater susceptibility to

boron deciency in traditional plain areas (Bharati andNeupane 1991; Erskine et al. 1998; Srivastava et al. 2000).The crossbred ILL 7986 was the rst large-seeded genotypeto produce more than 1 t/ha under the mid-hill rainfedenvironments of the Kathmandu Valley of Nepal due toits reduced photoperiod sensitivity (owered in 83 days)trait derived from the large-seeded parent ILL 4605 fromArgentina (Mediterranean-type environment) (Khanna-Chopra and Sinha 1987), its long reproductive growth periodof 82 days, and its early maturity of 165 days comparedwith the late owering (132 days) and maturity (178 days)in the large-seeded West Asian genotypes. Moreover, thelarge leaets, lack of pubescence, and large white owersof ILL 7986 make it clearly distinguishable from the locallandraces or cultivars in farmers elds, thereby preventingthe sale of its seed under a false name. Thus, the large-seeded trait of the Mediterranean types can be transferredto South Asian genotypes without detrimentally affectingthe adaptation of the South Asian genotypes. Also, the largevariance between rather than within groups suggests thegreater benet of crossing between the groups, rather thanwithin the groups.

In contrast to the phenological and morphological traitsdiscussed above, the crop water use (evapotranspiration)and root length density did not vary among the groups. Thehigh seasonal crop water use (278mm) in the West Asiangenotype ILL 7983 was largely associated with a longerperiod of growth and ability of this late West Asiangenotype to use the late-season rainfall in the year of study.Nevertheless, the West Asian genotypes were not able totake advantage of this late rainfall, still producing very lowyields. The measured seasonal crop water use (194278mm)


was similar to that reported in Syria (213326mm, Silimet al. 1987); India (115228mm under a range of watersupplies, Saraf and Baitha 1985), and Western Australia(174273mm, Siddique et al. 2001), giving us condencethat the measured crop water use captured most of the cropwater use and was not confounded by losses through deepdrainage or run-off. Recognising that the soil evaporationin this study in the post-rainy season may be less than in aMediterranean environment, it is interesting to note that theWUEDM values estimated for the South Asian and crossbredgenotypes (8.218.9 kg/ha.mm) were comparable withthose reported by Zhang et al. (2000) (9.218.1 kg/ha.mm),Silim et al. (1993) (7.913.8 kg/ha.mm) and Siddique et al.(2001) (8.516.7 kg/ha.mm), and the WUEgrain for thehigh-yielding genotypes (5.97.0 kg/ha.mm) was similar toor slightly lower than those reported by Silim et al. (1993)(6.3 kg/ha.mm), Silim et al. (1987) (9.05 kg/ha.mm), andYusuf et al. (1979) (8.2 kg/ha.mm) under adequate watersupply, Siddique et al. (2001) (2.47.2 kg/ha.mm) underrainfed Mediterranean-type environments. West Asianlentils, on the other hand, had markedly lower water useefciencies even for dry matter production in the mid-hillenvironment of Nepal compared with the South Asian andcrossbred genotypes.

Conclusions

This study has shown the superior adaptation of the crossbredand South Asian lentil genotypes compared with theWest Asian genotypes to the rainfed mid-hill environmentsof the Kathmandu Valley of Nepal. The small numberof pods and seeds per plant and poor seed yield in theWest Asian genotypes are attributed to late owering andmaturity under the short days of the Kathmandu Valley.Morphologically, the crossbred genotypes are closer toSouth Asian genotypes than the West Asian genotypes.The crossbreds had signicantly higher yields than theSouth Asian genotypes. They inherited the rapid groundcover, high dry matter, and early owering traits from theSouth Asian parents while retaining the larger seed sizeof the parental genotypes from West Asia. The importanceof phenological adaptation coupled with greater seed size,provides an explanation for the superior performance ofthe crossbreds under the mid-hill environment of Nepal.Although this paper reports a single years results, the fact thatthe poor yield of theWest Asian lentils was a consequence oftheir inappropriate phenology, and not other adaptive traits,suggests that the results will apply generally and not varywith season. Future targetted crossing of superior parentalgenotypes between South and West Asian germplasms andearly generation selection and evaluation under a range ofenvironments in Nepal could lead to further improvementsin the adaptation and seed yield of this important grainlegume crop.

Acknowledgments

Ms R. Shrestha gratefully acknowledges the support ofa John Allwright Fellowship from the Australian Centrefor International Agricultural Research (ACIAR). We thankDr D. Tennant for valuable guidance on soil water and rootlength measurements, and Dr S. Asseng and Dr H. Zhangfor their advice on root growth and water use data.Ms R. Shrestha records her gratitude to Prof. C. M. Francisof CLIMA, The University of Western Australia, for hisencouragement and support, ICARDA (Syria) for providingthe large-seeded and crossbred lentil accessions, and theNepal Agricultural Research Council (NARC) for theexperimental facilities.

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Manuscript received 11 February 2005, accepted 23 June 2005

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113. Growth and Seed Yield of Lentils Genotypes