Water relations, gas exchange and growth of cool-season grain legumes in a Mediterranean-type environment

Transcription

1 European Journa of Agronomy 9 (1998) Water reations, gas exchange and growth of coo-season grain egumes in a Mediterranean-type environment L. Leport a,*, N.C. Turner a,b, R.J. French a,c, D. Tennant d, B.D. Thomson a, K.H.M. Siddique a,d a Centre for Legumes in Mediterranean Agricuture, University of Western Austraia, Nedands, WA 6907, Austraia b CSIRO Pant Industry, Private Bag, PO, Wembey, WA 6014, Austraia c Agricuture Western Austraia, PO Box 43, Merredin, WA 6415, Austraia d Agricuture Western Austraia, Locked Bag No. 4, Bentey, WA 6983, Austraia Received 8 May 1998; accepted 30 Juy 1998 Abstract The aim of this study was to identify the physioogica characteristics which may affect the yied of six coo-season grain egume species grown in a water-imited Mediterranean-type cimate in Western Austraia. The rate of net photosynthesis, stomata conductance and water reations were measured from fowering to compete eaf senescence in white upin, chickpea, faba bean, fied pea, grass pea and enti. In irrigated pants, the midday eaf water potentia was about 0.6 MPa in a species, whie the maximum rate of eaf photosynthesis was 30 mmo m s 1 for chickpea and white upin, and beow 0 mmo m s 1 for the other species. With the deveopment of water deficits, the eaf water potentia in rain-fed pants decreased to about 3 MPa in chickpea and enti and MPa in the other species. Photosynthesis and stomata conductance decreased markedy as the eaf water potentia decreased beow 0.9 MPa in a six species, incuding chickpea and enti, which showed a high degree of osmotic adjustment. Despite the simiarity in water use, restricted to the top 40 cm of soi, and water reations characteristics, yieds varied markedy among species. Yieds were strongy correated with eary biomass production and eary pod deveopment Esevier Science B.V. A rights reserved. Keywords: Drought; Grain egumes; Mediterranean environment; Photosynthesis; Water potentia; Water use 1. Introduction occupies more than 60% of the rain-fed area sown to grain egumes in Austraia (Siddique and Sykes, Crop and pasture egumes are important compo- 1997). However, it is poory adapted to the nents of the sustainabe egume-based agricutura 6.5 miion ha of fine-textured, neutra-to-akaine, system in the Mediterranean-cimatic region of red-brown earths and the shaow dupex sois southern Austraia (Siddique et a., 1993). present in the Mediterranean cimatic zone in Narrow-eafed upin (Lupinus angustifoius L.) south-western Austraia (Siddique et a., 1993). Therefore, other grain egumes are being sought * Corresponding author. Te.: ; for these sois (Siddique et a., 1993). Faba bean Fax: ; e-mai: eport@cyene.uwa.edu.au (Vicia faba L.) and fied pea (Pisum sativum L.) /98/$ see front matter 1998 Esevier Science B.V. A rights reserved. PII S (98)0004-

2 96 L. Leport et a. / European Journa of Agronomy 9 (1998) have been shown to be high yieding when funga prevai in chickpea (Morgan et a., 1991), itte diseases are managed, whie chickpea (Cicer arietinum osmotic adjustment was observed in narrow-eafed L.), enti (Lens cuinaris Med.) and white upin ( Turner et a., 1987). Thus, grain egume upin (Lupinus abus L.) are recognized as potentiay species appear to adopt a range of mechanisms to profitabe crops on these sois (Siddique maintain yieds under termina drought, from et a., 1993). In addition to these crops with drought escape to avoidance and toerance of immediate potentia, severa grain egumes with drought. onger-term potentia, such as grass pea (Lathyrus The present experiment was part of a two-year sativus L.), narbon bean (Vicia narbonensis L.) and study conducted at two sites in Western Austraia various Vicia species, have aso been identified as in 1993 and 1994, in which a wide range of coo- adapted to the sois and cimate (Siddique and season grain egume species were compared for Sykes, 1997). their abiity to adapt to a Mediterranean-type Mediterranean-cimatic regions are charac- environment. From the data on growth, deveopment terized by coo wet winters and hot dry summers. and yied, Thomson et a. (1997) and Rain-fed crops are sown in autumn and seed fiing Thomson and Siddique (1997) concuded that high occurs in spring as termina water deficits deveop yieds were associated with high vigour and eary ( Turner, 199). The fine-textured sois to which podding. The aim of the present study was to these grain egumes such as faba bean, fied pea, determine whether other factors affected yied by chickpea and enti are adapted occur primariy identifying the physioogica differences among where the growing-season rainfa is ess than promising coo-season grain egume species which 50 mm. Therefore, the major constraint in these may hep in understanding their adaptation and regions is a short growing season and termina yied in ow-rainfa environments. The water rea- drought. Crops can adapt to drought using three tions, gas exchange and osmotic adjustment of different strategies: escape, avoidance or toerance, white upin, chickpea, faba bean, fied pea, grass as reviewed by Ludow (1989). Loss and Siddique pea and enti during termina drought were studied (1994) showed that in wheat grown in this environment, on a fine-textured, neutra-to-akaine soi at drought avoidance rather than drought to- Merredin in Western Austraia in 1994, a season erance is the major feature conferring adaptation with beow-average rainfa. to the environment. In faba bean, it has aready been reported (Siddique et a., 1993) that drought escape is a key characteristic for adaptation to. Materias and methods Mediterranean environments of Austraia, mainy through eary vigour and eary pod deveopment. White upin (Lupinus abus L. cv. Kiev mutant), In contrast to faba bean, the same authors reported chickpea (Cicer arietinum L. acc. T1587), faba that in narrow-eafed upin, fowering and pod set bean (Vicia faba L. cv. Fiord), fied pea (Pisum occurred when spring temperatures and soi moisture sativum L. cv. Dundae), grass pea (Lathyrus sati- deficits were increasing. Turner and Henson vus L. acc. 453), and enti (Lens cuinaris Med. (1989) studied narrow-eafed upin in the same cv. Digger) were grown on a red-brown earth environment as this study, but on coarse-textured ( United States Department of Agricuture soi ow-ph sois, and showed that the rate of eaf cassification: Cacic Hapoxeraf ) at Merredin, photosynthesis was high when pants were ade- Western Austraia (31 30 S, E). The tria quatey watered, but decreased much more rapidy was part of a two-year study conducted at two than wheat when soi and pant water deficits sites in Western Austraia in 1993 and The deveoped, eading to very ow rates of eaf photosynthesis fied site, experimenta design and agronomic during pod set and seed fiing in upin. detais of the tria (Merredin 1994) used for this Whie osmotic adjustment has been shown to vary with species (Turner and Jones, 1980) and to be important in maintaining yieds when water deficits study have been described previousy by Thomson et a. (1997). Briefy, the tria was of a randomized bock design with four repicates of each grain

3 L. Leport et a. / European Journa of Agronomy 9 (1998) egume species. The crops were sown on 4 May and rain-fed pants to measure the turgid 1994 in pots.16 m wide (1 rows, 18 cm apart, weight/dry weight ratio ( TW/DW ), reative water 34 cm between pots) and 40 m ong and at a content (difference between fresh weight and dry seeding rate which gave fina pant popuations, weight/difference between turgid weight and dry measured shorty after emergence, of weight) and osmotic potentia. The fresh weight 41 pants m for white upin, 45 pants m for was determined on eaves harvested around chickpea, 36 pants m for faba bean, midday, and the turgid weight on the same fuy 38 pants m for fied pea, 37 pants m for grass rehydrated eaves after inserting the petioe of the pea, and 114 pants m for enti. Target densities eaf into freshy deionised water for 4 h in a cosed, were based on experience gained from previous darkened, humidified chamber, and dry weight years, and foowed oca recommendations for after eaves were dried at 70 C for 48 h ( Turner, each species ( Thomson et a., 1997). Rainfa 1981). At the same time, equivaent eaves were during the season (May October) was recorded at samped and immediatey frozen for osmotic the site. A 5 m section at one end of each pot was potentia measurements. Osmotic potentia was drip-irrigated twice weeky, commencing at fow- measured on expressed sap by vapor pressure ering and ending just before maturity. The amount osmometry using Wescor ( Wescor, Logan, Utah, appied was equivaent to pan evaporation, corre- USA) C-5 sampe chambers and a Wescor sponding to 15 mm of water appied over a 50-day HR-33T dew-point microvotmeter. The osmotic period (Thomson et a., 1997). potentia at fu turgor (p ) was cacuated from: 100 The eaf water potentia (Y ) of upper expanded p =p RWC, eaves was measured around soar noon 100 (10:30 14:30 h) on cear sunny days at approxi- where RWC is the reative water content and p is matey weeky intervas between 84 and 16 days the measured osmotic potentia at that RWC. The after sowing (DAS) using the pressure chamber eve of osmotic adjustment was estimated from technique (Schoander et a., 1964) and foowing the difference in p between eaves from the rain- 100 the precautions recommended by Turner (1988). fed and irrigated pants ( Turner, 1981). Diution For the measurement of Y in chickpea and enti, of sympastic water by apopastic water is possibe the proxima four eafets were removed before the when using sap expressed from frozen and thawed eaf midrib was inserted into the pressure chamber. tissues ( Wenkert, 1980), eading to higher For fied pea, the eaf remained attached to the measured osmotic potentias than in the ces node when paced in the chamber so that the sea and possiby an underestimation of osmotic coud be camped against the soid part of the adjustment. node. The rate of decrease of Y with time Every two weeks, pants from the rain-fed por- (expressed in MPa d 1) was determined by inear tion of each pot were cut at ground eve within regression. At the same time and on simiar eaves one 0.5 m quadrat, dried at 70 C and weighed to those measured for eaf water potentia, the ( Thomson and Siddique, 1997). At maturity, rate of net photosynthesis and the stomata conductance pants in both the rain-fed and irrigated pots were were measured with a portabe, open cut at ground eve within two 0.5 m quadrats, gas-exchange system (Mode LCA3, ADC, dried at 70 C and weighed. The seeds were then Hoddesdon, UK). After measurement, the part of separated and weighed. At the same time that the eaf inserted into the cuvette was paced in a biomass sampes were taken, soi water content rapid-sea pastic bag and its area measured with was measured at 0 cm intervas from 10 to 170 cm an area meter (Deta-T Devices, Cambridge, UK) depths in the soi by the neutron scattering tech- to aow cacuation of the rate of net photosynthe- nique using a Mode 503 DR CPN moisture meter sis and the stomata conductance per unit eaf area (Caifornia Pacific Nucear, Caifornia, USA). (m). Statistica anayses were performed using SAS On 9, 105, 119 and 16 DAS, fuy expanded (SAS Institute, 1987). Means and standard errors upper eaves were aso samped from both irrigated were cacuated with the SAS MEANS procedure

4 98 L. Leport et a. / European Journa of Agronomy 9 (1998) and tests for differences among species and treat MPa d 1. Significant differences among ments were performed using a one- and a two-way treatments were observed in enti, white upin and ANOVA, respectivey (SAS genera inear mode grass pea at 9 DAS, and in a species by 105 procedure). Significant differences (P>0.05) were DAS. After 11 DAS, Y decreased beow identified with the LSD test. 1.5 MPa in a species. By this time, Y of chickpea was decreasing at a rate of 0. MPa d 1, that of enti, white upin and grass pea by 3. Resuts 0.1 MPa d 1, and that of faba bean and fied pea by ess than 0.1 MPa d 1. By the fina measurement on 16 DAS, the Y vaues of chickpea and Growing-season rainfa (May October) in 1994 was 173 mm, 54 mm ess than the ong-term enti were significanty the owest ( 3.3 MPa), average. In the irrigated crops, Y was between whereas in white upin and grass pea the vaues 0.5 and 0.9 MPa throughout the growing of Y were.1 to.3 MPa, and above season, and was not significanty different among.0 MPa in fied pea and faba bean. species at any samping time ( Fig. 1). At 84 DAS The mean photosynthetic rate of the irrigated (mid-august), Y was aso about 0.7 MPa in a pants varied from 6 to 7 mmo CO m s 1 in the rain-fed pants, but over the next four weeks chickpea and white upin, 19 mmo CO m s 1 Y decreased in a species at an average rate of in enti to 1 15 mmo CO m s 1 in grass pea, fied pea and faba bean (Fig. 1). At the same time, mean stomata conductance varied from 510 mmo m s 1 in chickpea and white upin, 400 mmo m s 1 in enti to 50 mmo m s 1 in grass pea, fied pea and faba bean (Fig. 1). At 84 DAS, the rain-fed pants had rates of net photosynthesis simiar to those in the irrigated pants in a species. By 105 DAS, five days before pod set in grass pea and 5 10 days after the beginning of pod set in a the other species, photosynthesis had decreased markedy to around 10 mmo CO m s 1 in chickpea and grass pea, and beow 5 mmo CO m s 1 in the other species. The decrease in eaf photosynthesis paraeed a decrease in stomata conductance to beow 100 mmo m s 1 in chickpea and beow 35 mmo m s 1 in enti, upin and grass pea (Fig. 1). At 11 DAS, when Y began to decrease sharpy, net photosynthesis was aready beow 5 mmo m s 1 in a the rain-fed pants and remained sighty positive over the next two weeks in chickpea, white upin and grass pea (Fig. 1). At Fig. 1. Changes with time of the midday eaf net photosynthetic this time, stomata conductance was significanty rate, the midday eaf stomata conductance, and the midday ower in rain-fed crops than in irrigated crops in eaf water potentia of six irrigated (open symbos) and six a species, with vaues not significanty different rainfed (cosed symbos) grain egume species grown in the fied among species (Fig. 1). By 11 DAS, ony 30 50% at Merredin, Western Austraia, in For carity, three of the eaves were sti green in these species species are presented in A and three in B. Vertica bars denote ( Thomson and Siddique, 1997). Measurements ±one standard error of the mean of 6 1 measurements, where these are greater than the size of the symbo. Arrows indicate were terminated on 130 DAS when a the eaves the time that the first pod was observed in rainfed crops. were senescent in a species.

5 L. Leport et a. / European Journa of Agronomy 9 (1998) Fig. 3. The changes with time in the above-ground biomass in six grain egume species grown under rain-fed conditions in the fied at Merredin, Western Austraia, in For detais of Fig.. The changes with time in the cacuated eaf osmotic symbos, see Fig. 1. potentia at fu turgor (p ) in six irrigated (open symbos) and 100 rainfed (cosed symbos) grain egume species grown in the fied at Merredin, Western Austraia, in Vertica bars denote ±one standard error of the mean of four repicates, where these respectivey, but in enti and grass pea, soute oss are greater than the size of the symbo. had occurred in rain-fed pants and the osmotic adjustment had decreased to zero. The TW/DW The cacuated osmotic potentia at fu turgor ratio measured in rain-fed pants decreased sighty was about 1 MPa in the irrigated crops of a in a species as the drought deveoped. At a species at a times of samping (Fig. ) and was times of measurement, the TW/DW ratio was not significanty different in rain-fed crops unti highest in faba bean and owest in enti ( Tabe 1). 105 DAS. By 119 DAS, osmotic adjustment, measured The biomass production of the six puses as the difference between the irrigated and varied markedy. In the rain-fed pots, biomass rain-fed pants at fu turgor, was MPa in production increased rapidy in faba bean and a species. It was the greatest in enti (0.6 MPa) fied pea, obtaining maximum vaues of and east in white upin, grass pea and faba bean g m ( Fig. 3). Grain yieds of these two ( MPa). In eaves coected seven days ater species were greater than 100 g m ( Tabe ). By (16 DAS), the osmotic adjustment had increased contrast, white upin and chickpea grew sowy, in chickpea and fied pea to 0.6 and 0.4 MPa, with maximum biomass production of 160 and Tabe 1 The turgid weight/dry weight ratio at four times during pod fiing in the six rainfed grain egume species grown in the fied at Merredin, Western Austraia, in 1994 Species Turgid weight/dry weight ratio 9 DAS 105 DAS 119 DAS 16 DAS Lenti 5.05a 4.8a 3.6a 4.15a Chickpea 5.59ab 5.08b 4.56b 4.76a Fied pea 6.47c 5.50b 4.79bc 4.83a Grass pea 6.33bc 5.35b 5.40c 5.90b White upin 6.76c 6.33c 6.d 6.30bc Faba bean 7.84d 6.39c 6.91d 6.98c A separate ANOVA was performed for each date. Vaues with the same etter within a coumn are not significanty different (P>0.05).

6 300 L. Leport et a. / European Journa of Agronomy 9 (1998) Tabe 4. Discussion Grain yieds for the six grain egume species grown under irrigated and rainfed conditions in the fied at Merredin, Western Austraia, in 1994 When the soi water suppy was pentifu, significant differences in the rate of net photosynthesis Grain yied (g m ) and stomata conductance among the grain egume Species Irrigated Rainfed species were observed. The rate of net photosynthesis per unit eaf area was highest in white upin Faba bean 400a 135a and owest in faba bean. In contrast to the observa- Fied pea 3bc 104ab tions of Henson et a. (1990) with L. cosentinii, Lenti 76b 7bc we observed no decrease in photosynthesis with Grass pea 96d 5c Chickpea 164cd 48c eaf age in the irrigated pants. Athough there White upin 18c 33c were differences among species in eaf photosynthesis and in stomata conductance at high eaf water An ANOVA was performed for each treatment. Vaues with potentias, the decrease in eaf photosynthesis and the same etter within a coumn are not significanty different (P>0.05). conductance with the decrease in Y was remarka- by simiar in a species (Fig. 4). There was a 10 g m and grain yieds of 33 and 48 g m, marked decrease in the rate of net photosynthesis respectivey. Lenti and grass pea showed interme- and stomata conductance when Y was 0.8 to diate performance with a maximum biomass propotentia at which photosynthesis decreased mark- 0.9 MPa. This is very simiar to the eaf water duction of g m and grain yieds of 5 7 g m. In the irrigated pots, the above- edy in narrow-eafed upin (L. angustifoius) ground biomass varied from more than ( Turner and Henson, 1989) and L. cosentinii 700 g m in faba bean to around 400 g m in ( Henson et a., 1989). The rate of photosynthesis white upin, and grain yied varied from at Y above 0.8 MPa in white upin was aso 400 g m in faba bean to ess than 100 g m in simiar to that in other upin species (Turner and grass pea ( Tabe ). Despite the differences among Henson, 1989). In both narrow-eafed upin and species in biomass production and grain yied, L. cosentinii, these authors showed the rate of net tota water use, water use before podding and photosynthesis decreased markedy at Y at which water use after first pod set were not different abscisic acid increased in the eaves, suggesting among species (Tabe 3). The profie of water use that the stomata cose in response to the accumua- with depth did not show any significant differences tion of abscisic acid in the eaf ( Turner and among species (data not shown). The difference Henson, 1989). Our data support their findings. between the wettest and the driest profies showed that amost a avaiabe water was extracted from the upper 40 cm of the soi. The major differences among the species were (i) the variation in osmotic adjustment; (ii) the ower vaues of Y in enti and chickpea; and (iii) Tabe 3 Tota, pre- and post-podding water use of six grain egume species grown under rain-fed conditions in the fied at Merredin, Western Austraia, in 1994 Tota water use (mm) Pre-podding water use (mm) Post-podding water use (mm) Faba bean Fied pea Lenti Grass pea Chickpea White upin A separate ANOVA was performed for each measurement. Vaues are not significanty different within each coumn (P>0.05).

7 L. Leport et a. / European Journa of Agronomy 9 (1998) Fig. 4. The reationships between the rate of net photosynthesis and eaf water potentia (A) and stomata conductance and eaf water potentia (B) in the six grain egume species grown in the fied at Merredin, Western Austraia, in the abiity of chickpea to maintain positive rates of photosynthesis at vaues of Y beow 3.0 MPa. In chickpea, the maintenance of a ow but positive photosynthetic activity in the eaves is not associated with a significanty higher water use of this species. Deeper root deveopment does not appear to be a characteristic of adaptation to drought under the imited rainfa of our experiment as root growth was imited to the first 40 cm of soi, the depth of the wetting front in this dry year. Maintenance of a ow photosynthetic activity in chickpea may be reated to its abiity to adjust osmoticay in response to decreasing eaf water potentia. Osmotic adjustment has been aready reported in some chickpea and fied pea genotypes subjected to water shortage ( Morgan et a., 1991; Rodríguez-Maribona et a., 199). The ow eaf water potentia observed in enti was aso associated with a arge degree of osmotic adjustment, however, osmotic adjustment was ost by the fina samping when eaf photosynthesis had decreased to zero. Within a species, there is a negative association between the TW/DW ratio and the degree of osmotic adjustment ( Turner et a., 1987). In rain-fed pants the highest TW/DW ratio was observed in faba bean and the owest TW/DW ratio was observed in chickpea and enti, which is consistent with the greater degree of osmotic adjustment in chickpea and enti and sight osmotic adjustment in faba bean. In contrast to the views expressed by Subbarao et a. (1995), we suggest that osmotic adjustment, which occurred ate in the season, did not maintain active growth in chickpea and enti because it ony occurred once rates of photosynthesis were ow, eaf growth had ceased, and very itte soi moisture was avaiabe for crop growth. Whie osmotic adjustment appeared to have itte benefit in maintaining high rates of photosynthesis, it coud pay a roe in maintaining positive rates of photosynthesis, abeit at a ow eve, at ow eaf water potentias in chickpea. This maintenance of a ow eve of photosynthetic activity may be critica in providing the energy required to maintain transocation and the transfer of carbon and nitrogen from the eaves, stem and roots to the deveoping seed. In a species except faba bean and fied pea, pod fiing occurred when the rate of eaf photosynthesis was reduced by haf to two-thirds of that the maximum, corresponding to assimiation rates beow 15 mmo CO m s 1 in chickpea, beow 10 mmo CO m s 1 in white upin and enti, and beow 5 mmo CO m s 1 in grass pea. This suggests that in this environment, the abiity of grain egume species to store assimiates during vegetative growth and remobiize them to the seeds under drought may be important in maintaining seed yied, as has aready been demonstrated in wheat (Pata et a., 1994). Despite the simiarity in tissue water reations under we-watered conditions and the response of the six species to water deficits, the species varied consideraby in yied under both irrigated and rain-fed conditions ( Tabe ). Yieds were strongy associated with green area index ( Thomson and Siddique, 1997), biomass production ( Fig. 3) and eariness of podding (Fig. 1). Thomson et a. (1997) suggested that rapid winter growth and eary fowering and maturity are critica for high seed yieds in grain egumes for ow rainfa regions. In our study, the species with the owest rates of

8 30 L. Leport et a. / European Journa of Agronomy 9 (1998) net photosynthesis under adequate soi moisture, to drought escape wi be required if the crop is to i.e. faba bean and fied pea, had the most rapid be grown in coo, short-season Mediterranean- eaf area deveopment and ground cover ( Thomson type environments. and Siddique, 1997) and the highest yied under rain-fed conditions, and in the case of faba bean aso had the highest yied when irrigated (Tabe ). 5. Concusion In contrast to perceptions of faba bean as a drought-susceptibe crop suitabe ony for ong- Our resuts demonstrate remarkaby simiar season Mediterranean environments, it is capabe physioogica responses among the six grain egume of avoiding drought and producing very high yieds species of different growth habit and phenoogy in short-season Mediterranean-type environments when subjected to water deficits. We observed provided it is sown eary in autumn (Loss and simiar decreases of photosynthesis and stomata Siddique, 1997; Mwanamwenge et a., 1998). conductance with decrease in eaf water potentia Indeed, with this abiity to escape drought, faba in a six species. There was aso surprisingy itte bean represents an important winter crop in correation between tota water use or pre- or post- Mediterranean cimates. The species with the high- podding water use and yied. Indeed whie we est rate of net photosynthesis per unit eaf area reported significant variations in grain yied among under irrigated conditions, i.e. white upin, had a the species, no significant difference was found for ow yied under irrigated conditions, and the owest tota, pre- and post-podding water use or in depth yied ( Tabe ), owest biomass accumuation of water extraction. Likewise, there was itte correation ( Fig. 3) and sowest eaf area deveopment under between the net photosynthetic rate per unit rain-fed conditions ( Thomson and Siddique, eaf area or the water reations characteristics and 1997). their abiity to maintain a specific eve of yied Surprisingy, yieds in the rain-fed pots were under drought. Yied under drought conditions not correated with tota water use, or with either was, however, strongy correated with eary bio- pre-podding or post-podding water use. With fre- mass production and eary fowering and pod set, quent sma rainfa events during the vegetative as demonstrated by Siddique et a. (1993), Thomson phase, water not used in transpiration was ikey and Siddique (1997) and Thomson et a. (1997). to be ost by soi evaporation (Gregory and This ceary identifies drought escape as a major Eastham, 1996) and conservation of pre-podding contributor to drought resistance in this shortseason water use for the post-podding phase ceary had Mediterranean-type environment. However, itte benefit in this environment, as suggested from the maintenance of yied through drought escape is studies with cereas ( Turner, 1997). currenty not possibe in species such as chickpea The resuts of this study strongy suggest that which fai to set pods because of coo winter spring photosynthetic activity and its maintenance as temperatures. In chickpea, we suggest that charac- termina drought deveops is not as critica for teristics of drought toerance wi have to be identified yied of grain egumes as eary growth and eary if this species is to be better adapted to these pod deveopment in this short-season, water-im- short-season Mediterranean environments. ited environment ( Thomson et a., 1997). Eary growth and matching phenoogica deveopment to water avaiabiity have been shown to be impor- Acknowedgment tant in cereas (Loss and Siddique, 1994; Turner and Whan, 1995) and appear to be equay impor- We thank B. Waington, R. Eiers, M.D. Barr, tant in grain egumes. However, where eary podding J.M. Aurisch, L. Maioo and D.G. Abbott for is impossibe due to poor seed fertiization assistance with the measurements at the fied site, and pod initiation at coo temperatures, as occurs and L. Young for the day-to-day running of the in current genotypes of chickpea (Siddique et a., experiment. We are gratefu to B. Deboer and Dr. 1994), aternative drought resistance mechanisms R.J.N. Emery for hep with statistica anaysis. We

9 L. Leport et a. / European Journa of Agronomy 9 (1998) acknowedge M. Reader, and Drs. M. Dracup, potentia of eaves in mangroves and some other pants. Proc. Nat. Acad. Sci. USA 5, J. Pata and S.P. Loss for their usefu comments Siddique, K.H.M., Sykes, J., Puse production in on the manuscript. This research was supported Austraia, past, present and future. Aust. J. Exp. Agric. 37, by the Cooperative Research Centre for Legumes in Mediterranean Agricuture. Siddique, K.H.M., Waton, G.H., Seymour, M., A com- parison of seed yieds of winter grain egumes in Western Austraia. Aust. J. Exp. Agric. 33, Siddique, K.H.M., Sedgey, R.H., Davies, C.L., Punyavirocha, S., Genotypic differences in chickpea for pod set at ow References temperature during fowering. In: Internationa Symposium on Puses Research, Apri 1994, New Dehi, India. Indian Society of Puses Research and Deveopment Pubishing, Gregory, P.J., Eastham, J., Growth of shoots and roots, Kanpur, p. 85. and interception of radiation by wheat and upin crops on a Subbarao, G.B., Johansen, C., Sinkard, A.E., Rao, R.C.N., shaow, dupex soi in response to time of sowing. Aust. Saxena, N.P., Chauhan, Y.S., Strategies for improving J. Agric. Res. 47, drought resistance in grain egumes. Crit. Rev. Pant Sci. Henson, I.E., Jensen, C.R., Turner, N.C., Leaf gas 14, exchange and water reations of upins and wheat. I. Shoot Thomson, B.D., Siddique, K.H.M., Grain egume species responses to soi water deficits. Aust. J. Pant Physio. 16, in ow rainfa Mediterranean-type environments. II. Canopy deveopment, radiation interception and dry matter pro- Henson, I.E., Jensen, C.R., Turner, N.C., Infuence of duction. Fied Crops Res. 54, eaf age and ight environment on the gas exchange of upins Thomson, B.D., Siddique, K.H.M., Barr, M.D., Wison, J.M., and wheat I. Physio. Pant 79, Grain egume species in ow rainfa Mediterranean- Loss, S.P., Siddique, K.H.M., Morphoogica and physio- type environments. I Phenoogy and seed yied. Fied Crops ogica traits associated with wheat yied increases in Res. 54, Mediterranean environments. Adv. Agron. 5, Turner, N.C., Techniques and experimenta approaches Loss, S.P., Siddique, K.H.M., Adaptation of faba bean for the measurement of pant water status. Pant Soi 58, (Vicia faba L.) to dryand Mediterranean-type environments I. Seed yied and yied components. Fied Crops Res. 5, Turner, N.C., Measurement of pant water status by the pressure chamber technique. Irrig. Sci. 9, Ludow, M.M., Strategies of response to water stress. In: Turner, N.C., 199. Crop production on dupex sois, an intro- Kreeb, K.H., Ritcher, H., Hinckey, T.M. (Eds.), Structura duction. Aust. J. Exp. Agric. 3, and Functiona Responses to Environmenta Stresses. SPB Turner, N.C., Further progress in crop water reations. Academic Pubishing, Gravenhage, pp Adv. Agron. 58, Turner, N.C., Henson, I.E., Comparative water reations Morgan, J.M., Rodriguez-Maribona, B., Knights, E.J., and gas exchange of wheat and upins in the fied. In: Kreeb, Adaptation to water-deficit in chickpea breeding ines by K.H., Ritcher, H., Hinckey, T.M. (Eds.), Structura and osmoreguation, reationship to grain-yieds in the fied. Fied Functiona Responses to Environmenta Stresses. SPB Crops Res. 7, Academic Pubishing, The Hague, pp Mwanamwenge, J., Loss, S.P., Siddique, K.H.M., Cocks, P.S., Turner, N.C., Jones, M.M., Turgor maintenance by Growth, seed yied and water use of faba bean (Vicia osmotic adjustment, a review and evauation. In: Turner, faba L.) in a short season Mediterranean-type environment. N.C., Kramer, P.J. (Eds.), Adaptation of pants to water and Aust. J. Exp. Agric. 38, high temperature stress. Wiey, New York, pp Pata, J.A., Kobata, T., Turner, N.C., Fiery, I.R., Turner, N.C., Whan, B.R., Strategies for increasing pro- Remobiization of carbon and nitrogen in wheat as infuenced ductivity from water-imited areas through genetic means. In: by postanthesis water deficits. Crop Sci. 34, Sharma, B., Kushreshta, V.P., Gupta, N., Mishra, S.K. Rodríguez-Maribona, B., Tenorio, J.L., Conde, J.R., Ayerbe, (Eds.), Genetic Research and Education, Current Trends and L., 199. Correation between yied and osmotic adjustment the Next Fifty Years. Indian Society of Genetics and Pant of peas (Pisum sativum L.) under drought stress. Fied Crop Breeding, New Dehi, pp Res. 9, 15. Turner, N.C., Stern, W.R., Evans, P., Water reations and SAS Institute, SAS User s Guide, Statistica Version, 6th osmotic adjustment of eaves and roots of upins in response ed. SAS Institute Pubishing, Cary. to water deficits. Crop Sci. 7, Schoander, P.F., Hamme, H.T., Hemmingsen, E.A., Wenkert, W., Measurement of tissue osmotic pressure. Bradstreet, E.D., Hydrostatic pressure and osmotic Pant Physio. 65,