Constraint #1: Insufficient Natural Resource Management and Production Technologies

Research area: Pest and disease control through genetic and agronomic means

Activity #5: Early Generation (EG) selections/nematodes

U.S. researchers: None
HC researchers: Nchimbi-Msolla, Misangu, Ijani (TPRI)
Methodology: (EG selections are included under Constraint #4, Activity # 3). Approximately 187 F2 lines will be screened for nematode resistance at SUA and TPRI in collaboration with Dr. Ijani. Data on inheritance of resistance will be collected and lines showing resistance will be advanced for further evaluation of other traits.

Anticipated results: Additional improved varieties with pathogen resistance will be available to farmers/consumers.

Anticipated impact(s)

• There will be continuing improvement in bean production by participating farmers over the next five years.

Major Changes (Tanzania): The nematode resistant crosses were not screened for nematode resistance at TPRI. This was because our collaborator felt the number of F2 lines (187) was too large for him to handle. For this reason, we screened the lines for diseases to reduce the number by eliminating those which were susceptible to BCMV, ALS and CBB. Early generation (EG) selections were evaluated as planned.

Progress During Past Year (Tanzania): The nematode F2 resistant lines (187 lines) were screened for BCMV, CBB and ALS. Out of those lines, 19 were selected based on reaction to the above stated diseases, seed type and plant type. The 19 lines will be evaluated at SUA for other agronomic traits and for reaction to nematodes in the 2001 long rain season. Preliminary evaluations showed that lines IMC4 and IMC6A were the best performers in terms of disease reaction and seed yield. The IMC lines are the outcome of the crosses IPA 7419 x MCM 5001. Both of these lines are CIAT materials and MCM 5001 had nematode resistance and has moderate level of bruchid resistance. IPA 7419 also has resistance to nematodes according to screening previous done by Ijani. Other lines like NR22 also appeared to be promising in terms of disease resistance, especially for BCMV, rust and ALS.

Sixteen early generation (EG) lines were also evaluated in advanced yield trials in 1999 and during the long rain season 2000. Yield in 1999 ranged between 376 kg/ha to 1049 kg/ha and in 2000 yield ranged between 858 kg/ha to 1632 kg/ha (Table 5). The six best performing lines from this population have been selected and planted in the on farm trial during the short rains of 2000 in two villages – Msongozi and Maharaka. Selection of these lines was based on yield potential, plant type, seed type and disease reaction.

Current Status of Research: The on-farm evaluation of the early generation material continues. Data from on-farm trials will determine which lines will be presented to the variety release committee in 2001. Crosses have been made between the best performing EG selections and lines resistant to bruchids. One of the crosses is between EG 10 x (ROJO x RAZ), The nematode resistant lines will continue to be evaluated for yield, other agronomic traits and will be screened further for nematode resistance at different locations in the country where root-knot nematodes are a major production constraint.

Activity #6: Exchange of advanced lines between Tanzania and Malawi and other institutions

U.S. researchers: Myers, Temple
HC researchers: Nchimbi-Msolla, Misangu, Bokosi
Methodology: Advanced lines from SUA with improvement of various traits will be sent to Malawi for evaluation. This includes about 25 Early Generation (EG) selected lines and about 8 bruchid resistant lines. Similarly, lines from Bunda improved for disease resistance (CBB, BCMV and Halo blight) will be brought to Tanzania for evaluation. Tanzania will also receive a nursery for ALS screening from the Malawi National Program. Germplasm with more improved traits will be requested from other institutions like CIAT's CBB nursery and U.S. universities. Lines will be planted in observation trials at the research locations in Tanzania and Malawi and evaluated for diseases, adaptation, and agronomic traits.

Anticipated (1 year) results: Adapted bean lines with improved and acceptable traits will be selected.

Anticipated impact(s): Good performance breeding lines from other institutions will be obtained, and an expanded germplasm base for continued breeding efforts established; Improved varieties will be released to farmers and in use.

Major Changes: The Early Generation selections were not sent to Malawi because, when the breeder from Bunda College visited SUA he thought that these lines should be sent later this year (November 2000) so that they can be planted immediately after receiving them. Instead, the breeder from Malawi took Rojo, SUA 90 and Kablanketi varieties.

Progress During Past Year (Tanzania): Several breeding lines and varieties were exchanged between institutions. The bruchid resistant lines were sent to Bunda College in Malawi and they are now being evaluated. Nineteen breeding lines (B-lines) were received from Bunda College, these lines are reported to have resistance to ALS and other diseases. The seeds of these lines have been increased and will be further evaluated in the 2001 growing season. Four SMARC lines (lines with arcelin – with phaseolin and without phaseolin) important for bruchid resistance were received from Dr. Myers (Oregon State University) which originally came from University of Wisconsin. These lines included SMARC1-PN1, SMARC1-NN1, SMARC-PN1 and SMARC4-PN1. Crosses have already been made between Rojo and the SMARC lines. The F₁ seed have been planted so as to make backcrosses to Rojo.

Other germplasm received include Nuna bean varieties from Dr. Myers (Oregon State university). The seeds have been increased under irrigation. They will be evaluated in the field during the growing season to determine their potential for use in Tanzania.

Ten bean lines with some resistance to Bean Stem Maggot have been obtained from Selian Agricultural Research Institute. Crosses will be made between these lines and the SUA improved lines.

Malawi: The Malawi programme received the bruchid resistant lines (arcelin materials) from Tanzania. These materials were give to a MSc student Chipokosa for further evaluation. However, we had to retrieve the lines after he abandoned his research. They have been multiplied for evaluation in the 2000/2001 season. More germplasm will be exchanged in future and with other programmes that may need the germplasm, such as Mozambique.

See also discussion under activity #7 for an update on materials exchanged with LAC.

Current Status of Research: Some of the germplasm received have been used in crosses, some are being increased and others are being evaluated to determine their performance under field conditions.

Activity #7: Drought breeding materials

U.S. researchers: None
HC researchers: Mkandawire, Rweyemamu, Bokosi, Nchimbi-Msolla
Methodology: This activity continues collaboration via exchange of germplasm with the LAC Regional Project in the area of drought stress. Thirty-six materials that were obtained from México, CIAT, Cali, Honduras and Tanzania were evaluated at one location in Malawi and the study indicated that some materials were able to produce substantially under moderate stress. The materials were also given to South Africa and Tanzania Bean Programs. The evaluation has continued at one location in Malawi and in the two countries during FY 99. During FY 00 the materials will also be given to Zimbabwe, from whom we have received a request for these materials. During FY 00 the nursery will be narrowed down to two promising genotypes, viz.: G 4523 and PT 91082. These will be included in the bean-breeding scheme for yield and on-farm evaluation. Anticipated results of activity: It is hoped that the two materials will perform well under moisture stress and this will provide an alternative to ensure more bean production in the drought hotspot areas.

Anticipated impact(s): Yields of beans will be increased in drought prone areas; Socioeconomic status of farmers will improve with important alleviation of poverty and improvement in nutritional status of people in these areas.

Major Changes: None

Progress During Past Year (Tanzania): The 36 drought resistant materials obtained from Malawi were evaluated in Tanzania for two seasons in 1999 and in 2000 under moderate moisture stress. Most of these lines out yielded SUA 90. Seed yield in 2000 season ranged from 545 kg/ha – 1475 kg/ha (Table 6). Bean line DN 34 performed well in both years and it appeared to be resistant to the four diseases recorded (BCMV, ALS, CBB and Rust). The other line which performed well in terms of seed yield and diseases was HHL 30-75. Line DN 34 has a type II plant type and HHL 30-75 is type I. Both are red, but small seeded. Crosses have been made between these lines and an improved bruchid resistant line (ROJO x RAZ) with the aim of incorporating Zabrotes resistance and increasing seed size. Bean lines G4523 and PT91082 (originally supplied by the LAC – Mexico program) which performed well in Malawi did not performed well in Tanzania (in lowland areas of Morogoro). The LAC lines continue to be tested in Tanzania and Malawi.

A pot experiment was conducted at SUA, where eight of the most promising lines from the drought nursery were water stressed at different stages. DN 34 performed well in terms of yield component characteristics and seed yield in water stress conditions. The reason for its good performance under water stress appears to be its deep root system compared to other seven lines evaluated.

In another experiment, thirty six bean lines were tested for drought tolerance during the June – September 2000 period. Data analysis is still being done and detailed results will be completed by end of October 2000. Preliminary observations, however, indicate that differences in most variables may not be significant because of the unusual rainfall which fell during the months of July, August and September. The experiment will need to be repeated.

Malawi: The regional drought nursery was grown at Bunda during the 1999 cropping season. It was comprised of 36 materials from CIAT Cali (core collection with one evaluation at Chitedze, contributed by Dr. Chirwa, National Program Coordinator, Lilongwe), Honduras (LAC Regional Drought Nursery contributed by Dr. Juan Carlos Rosas), and Tanzania (given by Dr. Madata, National Program Coordinator, Mbeya) apart from a Malawi check. The nursery was grown as a RCB with three replications; each plot consisting of four 5m rows. The Bunda area typically has moisture stress towards end of January through to mid to late February each year. During this period in 1999, beans were flowering and podfilling so that the crop was under moderate stress for about three weeks. Seed yields at the end of the season were significantly different and ranged from 198 to 1430 kg/ha, with a mean yield of 696 kg/ha. One of the earlier promising lines (G4523) with 1430 kg/ha again produced significantly higher yields than the other materials under the natural moisture stress conditions.

Two materials that produced the lowest yields during the rainy season were removed from NBYT and replaced by G4523, PT91082, MD 23-24, and MD 30-75 from the regional drought nursery (RDN) (Table 7). A split plot design (irrigated during flowering and podding vs. none) was used. Planting was done in July and harvesting was completed in October 2000. As expected we experienced no rainfall during this period. Mean seed yields were 1343 kg/ha. Seed yields produced under drought stress were significantly lower (1127 kg/ha) than those under no stress (1560 kg/ha), an almost 30% yield depression. This provided the confidence that the level of stress was adequate. Under well-watered conditions 2-10, a Malawi landrace, and MD 23-24 produced highest yields. G4523 and MD 30-75 (from RDN) had lowest yields under well watered conditions, but maintained yields under drought-stress. A similar response was observed for LRK 34 and DOR 715, both from CIAT through the National Program. These materials could be said to be drought tolerant but lower yielding under good conditions. Other materials, including MD 23-24, had significantly depressed yields under drought stress. The materials from our RDN do not necessarily have angular leafspot (ALS) resistance, preventing them from being used directly, but rather, will be used as parents in crosses between drought and disease resistant lines.

Current Status of Research: This research started in 1999. This work need to continue for three more years, so that the crosses can be evaluated and the best lines selected for evaluation in the on-farm trials for release. The experiment will be repeated during the dry period of December 2000 to February 2001. Initial evaluation of the materials supplied from the LAC by Mexico indicates that lines are generally adapted to Malawi, but not Tanzania. This is not unexpected given the relative latitudes of the three countries.