Enhancing Adaptation and Utilization of Location-Specific Corn-Based Technologies in Major Corn Growing Areas (With six Project Components implemented in six sites)

Accomplishments

Farmer-Managed Trials

1. Variety trials for yellow, white and glutinous corn (5 to 8 farmer partners per site)
2. Integrated pest management trials (4 to 5 farmer-partners per site)
3. Tillage practices trials (Farmers’ practice vs Conservation Tillage) (5 to 6 farmer-partners using yellow corn and 2 to 3 farmer-partners using glutinous corn per site)
4. Corn-forage conservation trials (2 to 3 farmer-partner per site)
5. Corn-chicken integration (in Arakan, Cotabato, 5 farmer-partners)

Research Managed Trials

1. Biofertilizer on-farm trials (1 farmer-partner per site)
2. Conducted Farmers’ Field Day before corn harvest in each cropping season. This is being participated in by farmers, farmer-leaders, officials from the LGUs, private industries, and SCUs as a venue to showcase the technologies involved in the trials and to exchange information.
3. As a result of the Farmers’ Field Day in San Jose, Mindoro Occ. Last April 6, 2000, the mayor of San Jose provided additional funds to support the expansion in other selected barangays of the municipality and the Governor provided support, through their respective mayors and MAOs initiatives, to two other towns of Sablayan and Sta. Cruz to conduct similar FSRD&E activities.
4. Developed and produced of extension materials ready for mass printing on (1) Conservation Tillage practices in corn production after rice, (2) Corn forage conservation and utilization, (3) Corn production and management grown in paddy fields (Activities such as these are continuing)
5. Presented poster on “Conservation Tillage Technology” and “Corn-Chicken Integration” in the 4^th Asian Agriculture Congress last April 24-27, 2001 in Mandarin Hotel, Manila. The poster on “Conservation Tillage Technology” won the Best Poster Award among 186 poster entries
6. Presented oral paper in the Pest Management Council of the Philippines Scientific Conference last May 2-4, 2001, Pili, Camarines Sur (Activities such as these are continuing)
7. A multi-disciplinary team was formed and inter-institutional arrangement was made between UPLB, USM, RIARCs, RIARCs, LGU province and municipality
8. MOU were signed between governors, mayors, DA RED, RIARC Manager, President of SCUs, PAOs, and MAO of each selected site (Need to have a new one in areas where there are new elected mayors and governors)
9. Project in-house review is regularly scheduled

Breeding for Special Maize Types

 Study 1a. Sweet corn hybrid development

                                    The inbred lines available now in the breeding program will be grouped according to type of genes for sweetness i.e. shrunken, brittle or sugary. Line will be purified based on phenotype and molecular markers. The lines will be rated also for agronomic adaptation (vigor, flowering, reaction to natural occurrence of pests and diseases, prolificacy, husk cover, etc.) and quality (ear appearance, sweetness, taste). Crosses will next be made only within a genetic background. Performance trial will be made and agronomic and quality traits will also be evaluated. Promising hybrids will next be evaluated in more locations which are probable production areas. The results will then be used as the basis for commercial release.

 Study 1b. Sweet corn synthetic development

                        The outstanding lines in each genetic background would be recombined for two seasons for synthetic development. Afterwards, the outstanding entries will be subjected to preliminary (one location/one season) and advanced (two seasons/multi-location) yield trials.

 Study 2. Development of Hybrid and OPV of waxy corn

 Study 2a. Waxy corn hybrid development

                                    Only waxy gene is responsible for glutinous corn. The different inbred lines available in the breeding program will first be purified and seed increased. Crosses will then be made between genetic sources.

            A performance trial of the single cross hybrids in terms of suitability for green corn use or Cornik i.e. dried grain yield, will be seed increased for further testing in target production areas. The outstanding ones will then be released commercially.

 Study 2b. Waxy corn OPV development

                        Different populations of waxy corn will be rated for agronomic performance and quality. Outstanding populations will be subjected to inter-population improvement using half-sib family selection. Basis for selection will be prolificacy, yield of marketable ears, vigor, plant type, reaction to natural occurrence of pests and diseases, among others.

 Study 3. Development of Pop Corn Hybrid

                        Lines at early stage of inbreeding S2 will be extracted from different sources. Afterwards, crosses will be made between lines from different genetic background. A performance trial for yield and quality (% popping, expansion volume, tenderness, taste, etc.) of both the parents and the crosses will be made. Based on that, the outstanding entries will be seed increased for further testing in probable production sites. The outstanding hybrid/s to be identified would then be seed increased and commercially released.

                        Early generation testing is resorted to because of time limitation. This, incidentally, is alright because anyway pop corn is susceptible to inbreeding depression.

 Study 4. Development of QPM hybrid and opv

 Study 4a. QPM hybrid development

                        A yield trial of QPM hybrids from CIMMYT will be made together with some developed by the Program. This will be done in two locations. To seed increase the promising entries, the seeds of parental inbreds will be requested from CIMMYT. Those entries will the be further tested in more locations through the National  Cooperative Test which will be the basis for the commercial release.

             Study 4b. QPM opv development

                        A yield trial of different QPM populations (elite variety trial and/or experimental variety trial) will be requested from CIMMYT. The result of the trial will be the basis of selecting which population to pursue. The seeds of the concerned population/s will then be requested for subsequent intra-population improvement using half-sib selection. Appropriate checks (non-QPM) will be included in the yield test. After two cycles, the material will be subjected to the National Cooperative Test (NCT)

 Study 5. Development of hybrid or opv for high starch content

                        The presently available elite white and yellow inbred lines from the program will be characterized for starch content. Within a grain color, crosses will be made between high starch lines. If the lines would be coming from different heterotic groups, hybrids will be made. Otherwise, a synthetic will be made. The synthetics or hybrids to be generated will then be subjected to a test for grain and starch yield. Promising hybrids will be further tested in more locations through the National Cooperative Test for Corn. The selected entries will then be seed increased and commercially released.

 Activities Undertaken

In the development of waxy corn hybrid, 90 inbred lines will undergo topcrossing using four parental inbred lines (PG6, PG8, PG16 & PG18), These materials were planted early this September (Table 6).

In the development of OPV waxy corn, Cabarugis population was selected to undergo intra population improvement using S1 families selection. Seeds were prepared for performance trial on 3 locations this coming October 2002.

In order to diversify the range of germplasm for this study, further seed requests and collections from different sources/locations will be conducted.

Results obtained 3 promising hybrids that yielded significantly over the local checks. QPM hybrids namely, CZH01024 (entry #4), CZH01029 (entry #9) and CZH99058 (entry #16) (Figure.1), that we found to excel in the yield trial QHYBO2 from CIMMYT – Zimbabwe (Table 10).

These hybrids were again requested from CIMMYT-Zimbabwe. They will provide the hybrids as well as the inbreds which will be undergo location trials here in the Philippines. We expect to receive the seed shipment by third week of September.

CIMMYT also proposed to send more QPM Trials (hybrids and inbreds as well) for the program’s additional source of breeding materials.

Biochemical analysis was also conducted to evaluate lysine, tryptophan and protein content of yellow and white inbred lines produced by the program. Results will also be the basis for selecting QPM materials.

            Requested lines from CIMMYT with specially high starch content are still on the process. At present, available elite white and yellow inbred lines from the program were evaluated at the Analytical Laboratory of IPB. This was done to test and characterize the starch content and the amylose quality for the basis of selecting high starch lines, subsequently generating hybrids or synthetics.

            Results in the analysis of the first 40 yellow and special corn inbred lines (Table 7) and 40 white inbred lines (Table 8) were done..

 Utilization of Heterosis in White Corn Breeding

Study 1. Diversification of heterotic combinations

            All the available inbreds of the program were planted at IPB Tranca during 2001 dry season and CMU, Musuan, Bukidnon. Out of the 272, only 147 were successfully seed increased by selfing and sibbing (129 selfed and 18 sibbed). Those 147 represented about 40 different source populations (Table 1). In addition, 75 early generation inbreds extracted from different sources were further advanced by selfing (Table 2).

            During the 2002 wet season, 36 inbreds representing 36 different source populations and or pedigree was planted for Design II crossing (Table 3). Reciprocal crosses will be bulked to maximize F1 seed production from the 324 single crosses that will be generated (18 male x 18 female parents). Seeds from the crosses will be harvested by mid august 2002. Two sets of the inbreds lines were planted in two areas namely F6 and C3 Tranca for seed increase. The early generation inbreds were also planted for top crossing to P8 and P75.

         To further diversify the range of germplasm for this project, different sets of yield trials were requested from CIMMYT and its different regional programs viz, Mexico, Thailand, Colombia, Zimbabwe and Kenya (Table 4). Seeds from Zimbabwe and Thailand were already received (Table 5, 6 & 7). The trials from Colombia were given to Dr. Nonito Franje of CMU for acid tolerance testing. Materials from ZImbabwe were harvested last March and yield trial results are given in Table 8. IPB Var 4 ranked fourth overall besting 15 other entries from EPOPO2 (Early Maturing Experimental Population trial). Seeds from the number one entry (ZM521-FLINT F2) were requested from CIMMYT-Zimbabwe for another round of testing and a possible utilization of such material. For EIHYBO2 (Early to Intermediate Hybrid Trial), IPB 2004 (a three-way white hybrid) was used as one of the checks and ranked number one (1) based on the average yield (t/ha) data. AG5355 (another check) ranked seventh (7^th).  

Study 2.  Use of molecular markers for determination of genetic relationship among lines and seed purification.

           The germinated seedlings from IPB 2001 dry season planting were sampled for DNA analysis. Actual analysis for SSR markers was however withheld because we would want to analyze only those lines where seeds were actually generated. (DNA from the 36 inbreds used for design 2 crossing during the 2002 wet season planting were also extracted and stored at  -20°C for analysis by SSR markers).

 Study 3.  Development of inbred-based populations

           There is no activity yet in this particular study. We have to wait for the initial results of Study 1.

 Study 4.  Development of package of technology (POT) for commercial seeds and grains production

            The parents of the two potential white corn hybrids of the Institute were seed increased. These are IPB 2004 and IPB 2006. They have one common parental inbred P75 but with different female single cross parents: (P12xP22) and (P1xP8) (Table 9). Five tons each of those are expected to be available by January 2003. The protocol for their seed production is expected to be done by that time.

            Activities are on tract with study 1. Generation of data will be delayed with study 2 due to lack of equipment. Study 3 and 4 will still be undertaken in the later part of the project.  

Development of Efficient Cell and Tissue Culture Regeneration System for Genetic Transformation of Maize Towards Improved Pest Resistance

Activity 1.      Planting of different maize genotypes as source of planting

material for tissue culture.

             A total of 46 out of 51 inbred lines acquired were planted in the field and evaluated for their tissue culture response (Table 1).  From the 46 inbred lines (Batch 1 and 2) already evaluated, 11 best responding inbred lines were selected based on production of embryogenic calli and shoot regeneration. These inbred lines are continuously planted in the field for a steady source of embryos for further experimentation. The 3rd batch of the maize genotypes undergoing evaluation includes 5 local yellow inbred lines.

Activity 2.  Callus induction and plant regeneration.

2.1.    Callus induction and  somatic embryogenesis in immature embryos cultured on different published media.

                        Immature embryos cultured in different published callus induction media produced two types of calli, embryogenic and non embryogenic (Fig. 1) Non embryogenic calli consist of compact or hard calli, soft and watery calli and these type of calli are not capable of regeneration.  The embryogenic calli either compact or friable are capable of producing plants.

             For the four inbred lines tested, the N6C1 and N6C1SN medium developed by CIMMYT gave the best response in embryogenic calli (E-calli) production (Table 3). For N6C1 the % E-calli ranged from 40-60% while for N6C1SN, % E-calli ranged from 55-80%.  These media identified as the best were used as the standard medium in subsequent experiments. However, due to high cost of the synthetic auxin Dicamba, an alternative medium containing 2,4-D is also used together with the 2 best media in all subsequent experiments.

            2.2.    Callus induction and plant regeneration responses of locally developed inbred lines.

             Embryogenic calli formation from the 24 locally developed inbred lines ranged from 0 – 96.2% (Table 4a-b). Two types of E-calli were produced: Type I, which is compact and nodular type of calli with many scuttelum like bodies (Fig. 1a) and Type II which is friable and creamy yellow in color (Fig. 1b).

               For the yellow inbred lines, E-calli formation ranged from 0-76.7%. (Table 4a).  Inbred line Pi 33 gave the highest % E- calli induction (76.7%, with CM3 medium) followed by Pi 23 (63.3%, with N6CI medium).  In terms of types of E-calli produced, inbred line Pi 33 produced the highest percentage of Type I E-calli (53.3%), while Pi 23 produced the highest Type II E-calli formation (40%) followed by inbred line P 65 (36.7%).  For most inbred lines tested, %E-calli formation was highest with N6C1 medium than CM3 medium.

                For the white inbred lines, E-calli formation ranged from 0-96.2% (Table 4b).  Inbred line P53 gave the highest E-calli induction (96.2%, with N6CI medium) followed by Var 2 (77.5%, with N6CI medium) and Var 4 (67.0%, with N6CI medium).   In terms of types of E-calli produced, inbred line P53 produced the highest percentage of Type I E-calli (68.7%), while P 65 produced the highest Type II E-calli formation (36.7%). For most white inbred lines tested, %E-calli formation was higher with N6C1 medium than CM3 medium,  Only 5 out 12 lines tested (41.7%) initiated calli in CM3 medium, while for N6CI  7 out of 12   (58.3%) of lines tested initiated calli.

              Percent shoot regeneration from E-calli ranged from 0-100%  for both yellow and white inbred lines. However, conversion of shoots into whole plant (with roots and shoots) was higher with the white inbred lines (0-100%, Table 5b) compared to yellow inbred lines (0-40.6%, Table 5a) Shoot and whole plant regeneration was higher in E-calli initiated from the N6C1 medium. Regenerated shoots from E-calli initiated in CM3 medium failed to develop into whole plants.

               Our basis for selecting the best responding genotypes is the ability to convert regenerated shoots into whole plantlets .  Although, some genotypes produced a high percentage of shoot regeneration, for example Pi 21 with 97.4%, only 7.9% regenerated into a whole plant  (with shoots and true roots). There were also some cases wherein some genotypes produced a high %E-calli, but very few or none at all  regenerated into shoots/plantlets.  In most cases only green points and shoot like structures were formed . In maize, the capacity to regenerate plantlets was correlated with the ability to form embryogenic calli, however, not all embryos producing embryogenic calli are capable of regeneration.  The highest whole plant regeneration was produced by Var 4 (100%, white inbred line) followed by Var 2 (57.1%, white inbred line), Pi 17 and Pi 23, both yellow inbred lines with 40.6%, and 16.0% regeneration, respectively)

        2.3             Callus induction and plant regeneration responses of CIMMYT inbred lines.

               For the 25 CIMMYT lines evaluated, E-calli formation ranged from 0- 15% using CM3 medium and 0-50% using N6CI medium . Sixteen out 25 (64%) lines tested responded to the N6CI, the callus induction medium developed by CIMMYT.  Inbred lines CIMMYT 2 and CL00331 produced the highest E-calli induction (50%). Most of the CIMMYT lines produced Type I and Type II E-calli and only two lines (CIMMYT 5 and CIMMYT 14) produced type II E-calli.

                Twelve out fifteen lines (80%)