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Vivek, B.

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Vivek
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Vivek, B.

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  • Stress-resilient maize for climate-vulnerable ecologies in the Asian tropics
    (Southern Cross Publishing, 2020) Zaidi, P.; Nguyen, T.; Dang Ngoc Ha; Thaitad, S.; Ahmed, S.; Arshad, M.; Koirala, K.B.; Rijal, T.R.; Kuchanur, P.; Patil, A.; Mandal, S.S.; Kumar, R.; Singh, S.B.; Bhupender Kumar; Shahi, J.P.; Patel, M.B.; Gumma, M.K.; Pandey, K.; Chaurasia, R.; Haque, A.; Seetharam, K.; Das, R.R.; Vinayan, M.T.; Rashid, Z.; Nair, S.K.; Vivek, B.
    Publication
  • Genomic regions associated with root traits under drought stress in tropical maize (Zea mays L.)
    (Public Library of Science, 2016) Zaidi, P.; Seetharam, K.; Krishna, G.; Krishnamurthy, L.; Gajanan, S.; Babu, R.; Zerka, M.; Vinayan, M.T.; Vivek, B.
    An association mapping panel, named as CIMMYT Asia association mapping (CAAM) panel, involving 396 diverse tropical maize lines were phenotyped for various structural and functional traits of roots under drought and well-watered conditions. The experiment was conducted during Kharif (summer-rainy) season of 2012 and 2013 in root phenotyping facility at CIMMYT-Hyderabad, India. The CAAM panel was genotyped to generate 955, 690 SNPs through GBS v2.7 using Illumina Hi-seq 2000/2500 at Institute for Genomic Diversity, Cornell University, Ithaca, NY, USA. GWAS analysis was carried out using 331,390 SNPs filtered from the entire set of SNPs revealed a total of 50 and 67 SNPs significantly associated for root functional (transpiration efficiency, flowering period water use) and structural traits (rooting depth, root dry weight, root length, root volume, root surface area and root length density), respectively. In addition to this, 37 SNPs were identified for grain yield and shoot biomass under well-watered and drought stress. Though many SNPs were found to have significant association with the traits under study, SNPs that were common for more than one trait were discussed in detail. A total 18 SNPs were found to have common association with more than one trait, out of which 12 SNPs were found within or near the various gene functional regions. In this study we attempted to identify the trait specific maize lines based on the presence of favorable alleles for the SNPs associated with multiple traits. Two SNPs S3_128533512 and S7_151238865 were associated with transpiration efficiency, shoot biomass and grain yield under well-watered condition. Based on favorable allele for these SNPs seven inbred lines were identified. Similarly, four lines were identified for transpiration efficiency and shoot biomass under drought stress based on the presence of favorable allele for the common SNPs S1_211520521, S2_20017716, S3_57210184 and S7_130878458 and three lines were identified for flowering period water-use, transpiration efficiency, root dry weight and root volume based on the presence of favorable allele for the common SNPs S3_162065732 and S3_225760139.
    Publication
  • Annual Research Report 1999: lowland tropical - HQ maize subprogram
    (CIMMYT, 1999) Cordova, H.S.; Vergara Avila, N.; Barandiarán, M.; Vivek, B.; Avila, G.; Ramírez A.; Alvarado Beltrán, G.; Cano, O.
    Inter-population improvement using reciprocal recurrent selection (RRS) in the tropical lowland, has been enhanced focussing on selection against biotic and abiotic stresses, with the support of the Entomology, Pathology and Physiology units. In the tropical subprogram one cycle of S2 recurrent selection will be completed in two years. The formation of new experimental varieties will be speeded-up. Two new sets of populations heterotic to each other (2 white and 2 yellow) are being formed. 22 new synthetic, OPVs were formed, advanced to F2 and tested in international trials; new synthetic cultivars are more uniform and more appealing to farmers. Yield in the synthetics is similar to the normal experimental varieties. Six synthetics resistant to insects (FAW), to drought and low nitrogen, were developed, advanced to F2 and will be tested in international trials in the year 2000. New com stunt disease (CSD) resistant synthetics: P73 NICI, P73 NIC2, P73 NISAl, yielded up to 7 .2 tons per hectare, under non infested conditions with a minimal decrease in yield of 7.1, 5.3 and 7.9% respectively under heavy CSD infection. The single cross hybrid CML24 7 x CML254 suffered a yield reduction of 4 7%. All 3 synthetics were resistant to B. maydis and P. polisora. 10 lines with good GCA adapted to tropical lowland, were identified and proposed for immediate release; some lines are resistant to insects, drought, low-N, foliar diseases and ear rot. 6 new white and yellow tropical elite inbred lines 'testers' were identified and are in current use. The new testers will eventually replace the earlier tropical testers. More than 1500 tropical new hybrid combinations with adaptation to tropical lowland, in Latin America and Asia were tested in several locations in stressed and non-stressed environments in 1999. Superior hybrids outyielded the best seed industry check up to 30% and, possessed superior agronomic traits. 8 QPM hybrids with tropical adaptation were released by INIFAP. The ceremony was attended by the Mexican Secretary of Agriculture, Prof. Timothy Reeves and Dr. Norman Borlaug. The best hybrids yield 10% better than the best seed industry checks and contain 60 to 100% more triptophan and lysine. It is planned to plant 500,000 ha of QPM in Mexico soon. In collaboration with RS and PRM, we released QPM hybrid HQ-61 in El Salvador. The ceremony was attended by the Vice President, Minister of Agriculture, Minister of Foreign Relations, Vice President of Nicaragua, public, private and seed industry representatives, Dr. Norman Borlaug and Dr. Shivaji Pandey and other CIMMYT Staff. The government of El Salvador presented a plan to cover 70% of the area planted with QPM maize in four years. The plan for seed production in 2000 is to produce 800 tons of seed to enable the planting of 40,000 hectares by 2001. In Guatemala we released HB-PROCTICTA with similar results as in El Salvador. In 1999 we tested 23 tropical QPM hybrids at 28 locations in Asia and Latin America. Best QPM hybrids outyielded the best seed industry checks by region and countries. Research in swine feeding conducted in September 1999 and January 2000 in El Salvador and in Guatemala is very promising and very similar to the earlier studies conducted in the 1970's and in 1994. In both cases, pigs fed with QPM gained 600 g/day while the ones fed with normal maize gained only 300 g/day. In collaboration with R5 and SAMP in Venezuela, FONAIAP tested tropical and CIMMYT Cali hybrids in seven locations in the State of Portuguesa. Results across several locations indicate that the CIMMYT hybrid CL02198 x CML274 yielded 10.5 t/ha and the best check 8.5 t/ha, while the Pioneer hybrid yielded 6.5 t/ha. QPM results in Venezuela are also very exciting. The hybrid (CML142 x CML15) x CMLl 76 topped the trial at Guarico with 6.5 t/ha, 15% more than the seed industry check. The best selected hybrid will be tested in strip tests in 2000. In Peru tropical yellow hybrids yielded up to 14 t/ha up to two tons more than the best checks. Superior hybrids identified will be evaluated in strip tests in 2000. In Colombia yellow QPM hybrid CML161 x CML165 and white endosperm (CML144 x CML159) QPM hybrids outyielded the best seed industry check G-5324 and Cargill C-343 respectively, by more than 1 t/ha with double lysine and triptophan content. QPM hybrids are being proposed for release in 2001. We have shipped 12 trials including QPM hybrids to Ecuador, Paraguay and Bolivia for the purpose of testing in multi-location trials in 2000. In Thailand G2 in collaboration with R2 and ARMP, tested six different trials at the Suwan Farm site. In each trial at least two entries outyielded the best seed industry check by 1-2 t/ha. Even allowing for heavy residual herbicide damage, CIMMYT tropical hybrids demonstrated superiority for yield potential and resistance to ear rot and P. polysora. G2 in collaboration with F4 identified 8 new white endosperm elite QPMs with good GCA for immediate release. The lines were identified from the results of advanced test crosses conducted in 10 locations during 1999/A and B cycles. New F2 pedigree breeding population using elite QPM lines and normal white and yellow elite coded inbred lines have been developed and pedigree selection will be continued in 2000. A very important alliance emerged between the CIMMYT Maize Program and Grupo Maseca-Central America Andean Region. Grupo Maseca visited the CIMMYT Maize Program in early February and expressed their desire to join forces with CIMMYT in promoting QPM hybrid maize in Central America (Guatemala, El Salvador, Honduras, Nicaragua and Costa Rica) and South America (Colombia, Venezuela) through promoting and recommending our hybrids released by National Programs in "El Club del Maiz de Maseca", using the most advanced agronomic technologies and the best QPM hybrids available. We had a meeting with the Directors also in Guatemala during the release of HBProticta. They are prepared to purchase the hybrid seed from small private companies in each country and distribute to farmers, eliminating the intermediaries. Our collaboration with SG2000 was enhanced during the meeting held at CIMMYT in November 1999. We presented a progress report on QPM development and transfer that was regarded as impressive by most of the members. An enhanced collaboration emerged from that meeting with the promise of more interaction for the promotion of our products to farmers. 1999 was very positive scenario for the relationship between CIMMYT's Maize Program and NARS in Mexico. A true partnership between INIFAP and CIMMYT was also established, with INIF AP providing 200 kg. of basic seed that was sent to Guatemala, for hybrid seed production. There also has been mutual public recognition of QPM development. Fundación Mexicana para la lnvestigaci6n Agricola also recognized our effort by granting 100,000 to CIMMYT to continue research on QPM. CIMMYT and Texas A&M have initiated a partnership by identifying areas of common interest and developing a joint proposal with emphasis on tolerance to drought and heat, aflatoxins and breeding for QPM hybrid development. In association with QPM germplasm improvement, assistance from the University of Arizona has allowed CIMMYT to produce antibodies that react with the maize elongation factor 1 a, that is highly correlated to lysine content of the endosperm. Antibodies were produced and provided to NARs with germplasm improvement programs for QPM maize. Serological tests will help in the selection process needed to develop QPM maize, using the ELISA technique.
    Publication
  • Relative importance of general combining ability and specific combining ability among tropical maize (Zea mays L.) inbreds under contrasting nitrogen environments
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 2008) Regasa, M.W.; Banziger, M.; Friesen, D.; Schulte auf'm Erley; Horst, W.J.; Vivek, B.
    Low-N stress is among the major abiotic stresses causing yield reductions in maize grown in the mid-altitude tropical environments of Africa. This study estimates the relative importance of general combining ability (GCA) and specific combining ability (SCA) in CIMMYT's tropical mid-altitude inbred lines under contrasting N environments. Six hundred and thirty five lines (S2-S7) were evaluated in different crossing designs (Diallels, North Carolina Design II and Line x Tester crosses). Results of experiments conducted under low and high N at the same site in adjacent fields with the same soil type within the same year and season from 1999-2003 were compared. The contribution of GCA to total genetic variation was higher than SCA for anthesis date, ear height and plant height under both high and low N levels. However, contribution of GCA was higher for grain yield only under high-N conditions. The average relative contribution of SCA, indicative of non-additive gene effects, to total genetic variation for grain yield under low-N accounted for 51% (average across all trials) but only for 36% under high-N. Pair-wise t-test for diallels and Design IIs showed significant difference (P<0.05) between the proportion of SCA sum of squares for grain yield under high and low N conditions. This implies that breeding strategies that increase grain yield under optimal (high N) conditions will not address the needs of a resource poor farmer producing maize under low N conditions, especially in sub-Saharan Africa. Targeted strategies that increase yield under low N conditions are thus required.
    Publication
  • Farmer perceptions on maize cultivars in the marginal eastern belt of Zimbabwe and their implications for breeding
    (African Crop Science Society, 2006) Derera, J.; Tongoona, P.; Langyintuo, A.S.; Laing, M.; Vivek, B.
    Productivity of maize ( Zea mays check for this species in other resources ) is low in the small-holder sector of Zimbabwe because the crop is grown under stress-prone environments and limited resources. The objective of this study was to investigate farmer perceptions on maize cultivars and their implications for breeding. Participatory rural appraisal and household surveys were conducted in the marginal eastern-belt of Zimbabwe, during 2004 to 2005. Although farmers predominantly grew hybrids, productivity (ranging between 240 and 500 kg ha-1) was below national average of 1 t/ha; hence grain deficit was rampant. Surprisingly, farmers preferred hybrids of the 1970s to new hybrids, due to their superior tolerance to abiotic stress. Farmers also preferred a local landrace "Chitonga", because of its superior taste and flint grain. Nonetheless, farmers recognized that both "Chitonga" and hybrids lacked the drought stress recovery mechanism; which is prevalent in sorghum, thus failed to fit into short seasons. Cultivar preferences were area-specific with farmers in more productive Mutasa showing high preference for grain weevil resistance, while those in Chipinge and Mutare West preferred cultivars with drought tolerance, among other traits. Besides conventional breeding, integrated use of participatory approaches and other appropriate technologies such as molecular technology to fix novel stress tolerant genes in ultra-cultivars for deployment in marginal areas is implied.
    Publication
  • Mejoramiento de maíz con calidad de proteína (QPM): protocolos para generar variedades QPM
    (CIMMYT, 2008) Vivek, B.; Krivanek, A.F.; Palacios-Rojas, N.; Twumasi Afriyie, S.; Diallo, A.O.
    Este manual, dirigido en primer lugar a los mejoradores de maíz que desean empezar a generar variedades de maíz con calidad de proteína (QPM), constituye una recopilación de varios protocolos de mejoramiento que se han aplicado con éxito en el CIMMYT durante las más de dos décadas que lleva generando y mejorando el QPM. Asimismo, brinda un resumen breve de los antecedentes fitotécnicos y de la teoría básica de los aspectos genéticos del QPM y detalla los métodos y procedimientos que se aplican en el mejoramiento del mismo.
    Publication
  • Characterization of maize germplasm grown in Eastern and Southern Africa: results of the 2004 regional trials coordinated by CIMMYT
    (CIMMYT, 2005) Vivek, B.; Banziger, M.; Pixley, K.V.
    The Summary Tables present grain yields averaged across sites with significant differences between entries, for each of the five to six environments. Data on agronomic performance such as anthesis date, plant and ear height, ear position, root and stem lodging, husk cover, ear rot, leaf diseases, grain weevil and stem borer damage, grain texture and grain moisture were averaged across all sites that provided results with significant differences between entries. If no data are presented for these traits, no trial data demonstrating significant differences for these traits was available.
    Publication