ciatapr10, ciat, poster, "poster Exhibit", beans, "Tropical Forages", biodiversity, agbio, poster23

1. Photosynthate remobilization to grain in common bean contributes to
improved resistance to terminal drought stress
Jose A. Polanía, M. Rivera, M. Grajales, C. Cajiao, S. Beebe and I. M. Rao
International Center for Tropical Agriculture (CIAT), A.A. 6713, Cali, Colombia
E-mail: j.a.polania@cgiar.org; i.rao@cgiar.org
Introduction Under rainfed conditions, significant genotypic differences
were observed in canopy biomass production at mid-pod
The elite lines SER 128, SER 78, SEA 15, NCB 226, SEN
56, SEN 36, SER 119 and SER 113 yielded well under
Drought is the major abiotic constraint affecting common filling growth stage (Figure 2). Higher values of canopy rainfed conditions due to greater ability to partition
biomass could indicate greater potential for remobilization photosynthetically assimilated carbon to pods as reflected
bean (Phaseolus vulgaris L.) production. About 60% of the of photosynthates to grain during drought stress. Cowpea
bean crop is cultivated under the risk of either intermittent cv. Mouride showed markedly greater value of canopy by higher values of pod partitioning index (Figure 3). The
or terminal drought (Beebe at al., 2008; Rao, 2001; biomass than the common bean genotypes. Among the line SER 118 was outstanding in remobilization of
White and Singh, 1991). The effects of drought on genotypes of P. vulgaris tested, NCB 226, SXB 418, DOR photosynthates under terminal drought stress as indicated
common bean are dependent on the intensity, type and 390, SER 78 and SER 113 were outstanding in canopy by greater values of both pod partitioning index and pod
duration of the stress. Improving drought resistance of biomass production. harvest index but it had lower value of canopy biomass
common bean varieties is an important research for (Figure 2, 3 and 4) indicating the need for adequate
development strategy to minimize crop failure and 1600 vegetative vigor to achieve higher values of grain yield. In
improve food security in bean growing regions. Field contrast to SER 118, cowpea cv. Mouride showed lower
Rainfed grain yield (kg ha-1)
1400 SER 78
studies conducted for the past few years indicated that the SER 128 NCB 280 NCB 226 value of pod partitioning index indicating a limitation on
superior performance of common bean genotypes under 1200 SEA 15
SER 119
SEN 36
G 40001 SEN 56 Cowpea M
remobilization of photosynthates to pod development.
both terminal and intermittent drought stress was 1000
EAP 9653-16B
SEA 5 SER 118
SER 113
SER 16
associated with their ability to remobilize photosynthates Mean: 898 A 774 Results on the relationship between rainfed pod harvest
800 SXB 405
from vegetative structures to developing grain. Among the LSD0.05: 319 Tio Canela
BAT 477
DOR 390 index (PHI) and rainfed grain yield indicated that two
plant traits evaluated using a large number of both elite 600 Perola
San Cristobal
SXB 418
small seeded red lines (SER 78, SER 128) and four small
lines and recombinant inbred lines, pod harvest index was 400 A 686 seeded black lines (NCB 226, NCB 280. SEN 36 and SEN
identified as a useful trait to consider in the breeding 56) were superior in mobilizing photosynthates from pod
200
program in addition to grain yield for identifying bean G 19902 wall to seeds (Figure 4). The PHI values of the two wild
genotypes that are better adapted to both terminal and 0 G 24390
Mean: 2781
LSD0.05: 981
bean accessions (G 19902 and G 24390) were markedly
intermittent drought stress conditions. We evaluated lower than that of other bean genotypes. Results on
drought adaptation of 36 genotypes including the elite 500 1000 1500 2000 2500 3000 3500 4000 4500 agronomic water efficiency indicated that the elite lines
lines and checks from the on-going breeding program with Rainfed canopy biomass (kg ha-1) SER 78, NCB 226 and SER 128 were highly efficient in the
the main objective of defining the physiological basis for Figure 2. The relationship between rainfed grain yield and use of water applied under rainfed conditions (Figure 5).
improved drought resistance. rainfed canopy biomass.
Correlation coefficients between grain yield and other
Materials and Methods 1600 shoot attributes indicated that seed yield was positively
related to canopy biomass, pod partitioning index and
Rainfed grain yield (kg ha-1)
1400 SER 78
SER 128
A field trial was conducted at CIAT-Palmira in 2009 (July 1200
NCB 280
NCB 226
SEN 36 SEA 15 pod harvest index under rainfed conditions (Table 1).
G 40001
to October) to determine genotypic differences in Cowpea M SEN 56 SER 119
tolerance to drought stress conditions. The trial included 36 1000 SXB 415 SER 16
SER 113
SER 109 Table 1. Correlation coefficients (r) between grain yield
and other shoot attributes under irrigated and rainfed
SEA 5 SER 118
genotypes: A 686, A 774, BAT 477, Carioca, Cowpea 800
Mean: 898 SXB 405 RCB 273 A 774
Mouride, DOR 390, EAP 9503-32B, EAP 9653-16B-1, G
LSD0.05: 319
SXB 418 Tio Canela
Carioca
conditions. *, **, *** Significant at the 0.05, 0.01 and
0.001 probability levels, respectively.
DOR 390 BAT 477
19902, G 24390, G 40001, NCB 226, NCB 280, Perola, 600 Perola
RCB 273, San Cristóbal 83, SEA 15, SEA 5, SEN 36, SEN 400
San Cristobal A 686
Plant traits Irrigated Rainfed
56, SER 109, SER 113, SER 118, SER 119, SER 125, SER
128, SER 16, SER 48, SER 78, SER 90, SXB 405, SXB 409, 200 Canopy biomass (kg ha-1) -0.01 0.59***
SXB 412, SXB 415, SXB 418 and Tio Canela 75. A 6 x 6 0 G 19902
Pod partitioning index (%) 0.49** 0.79***
G 24390
partially balanced lattice design with 3 replicates was Mean: 63
Pod harvest index (%) 0.64*** 0.61***
used. Two levels of water supply (irrigated and rainfed) 0 20 40 60 80 100
were applied. Experimental units consisted of 4 rows of
3.72 m long by 0.6 m wide. Canopy dry weight per area
was measured at mid-pod filling under rainfed and
Rainfed pod partitioning index (%)
Figure 3. The relationship between rainfed grain yield and
Conclusions
irrigated conditions in order to determine genotypic Field evaluation of elite lines at Palmira under terminal
rainfed pod partitioning index.
variation in drought resistance. At the time of harvest, drought stress resulted in identification of six small seeded
grain yield and yield components were determined. Pod
1600 common bean lines (NCB 226, NCB 280, SEN 56, SER 113,
partitioning index (dry wt of pods at harvest/dry wt of SER 78 and SER 128) that were outstanding in their
Rainfed grain yield (kg ha-1)
1400 SER 78
canopy biomass at mid-podfill x 100), pod harvest index 1200
SER 128 NCB 226
SEA 15 NCB 280 adaptation to terminal drought stress conditions. The
(dry wt of seed at harvest/dry wt of pod at harvest x SEN 36 G 40001
SEN 56 superior performance of these lines under drought stress
100), were also determined (Figure 1). 1000 SXB 415
SEA 5
SER 16 Cowpea M
SER 109
was associated with higher values of canopy biomass, pod
A 774 SER 118
800
Mean: 898
LSD0.05: 319
SXB 405 Carioca RCB 273
Tio Canela
partitioning index and pod harvest index reflecting the
BAT 477
600
SXB 418
DOR 390
Perola
contribution of remobilization of photosynthates to grain.
San Cristobal A 686 Further work is in progress to evaluate these lines for their
400 deep rooting ability under drought stress conditions.
200
0 G 19902
G 24390
Mean: 72
LSD0.05: 8
References
30 40 50 60 70 80 90 Beebe, S., I. M. Rao, C. Cajiao and M. Grajales. 2008.
Rainfed pod harvest index (%) Selection for drought resistance in common bean also
Figure 4. The relationship between rainfed grain yield and improves yield in phosphorus limited and favorable
environments. Crop Science 48: 582-592.
1 rainfed pod harvest index.
Rao, I. M. 2001. Role of physiology in improving crop
2 14 adaptation to abiotic stresses in the tropics: The case of
Irrig a te d
common bean and tropical forages. In: M. Pessarakli (ed).
Agronomic water efficiency
12 R a in fe d
Figure 1. Photosynthate remobilization pathway. 1 Handbook of Plant and Crop Physiology. Marcel Dekker,
(kg ha-1 mm-1)
Mobilization of photosynthates from leaves and stems to
10
Inc., New York, USA pp. 583-613.
pods (pod partitioning index). 2 Mobilization of 8 White, J. W., and S. P. Singh. 1991. Breeding for
photosynthates from pod wall to seed (pod harvest index) adaptation to drought. p. 501-506. In A. van Schoonhoven
Results and Discussion
6
and O. Voyset (ed.) Common beans: Research fro crop
4 improvement. CAB International. Wallingford, UK & CIAT,
2
Cali, Colombia.
During the crop-growing season, maximum and minimum
air temperatures were 32.6 oC and 19.4 oC. The total
rainfall during the active crop growth was 59 mm. The
0
Acknowledgements
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potential pan evaporation was of 482 mm. These data on
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This work is partially supported from the funds from BMZ-
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total rainfall and pan evaporation together with decrease
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in soil moisture across soil depth (-24 KPa in irrigated vs. - G e n o typ e s GTZ), Generation Challenge Program of CGIAR (Tropical
108 KPa ia rainfed at 60 days after planting at 40-60 cm Figure 5. Agronomic water efficiency (grain yield (kg/ Legumes I Project) and Bill and Melinda Gates Foundation
soil depth) indicated that the crop suffered severe terminal ha)/unit water applied (mm) of 12 genotypes grown under (Tropical Legumes I and II projects).
drought stress during active growth and development. irrigated and rainfed conditions.