Person: Ahmed, S.
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Ahmed
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Ahmed, S.
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- Heat-tolerant maize for rainfed hot, dry environments in the lowland tropics: from breeding to improved seed delivery(Institute of Crop Sciences, 2023) Zaidi, P.; Vinayan, M.T.; Nair, S.K.; Kuchanur, P.; Kumar, R.; Singh, S.B.; Tripathi, M.P.; Patil, A.; Ahmed, S.; Hussain, A.; Kulkarni, A.P.; Wangmo, P.; Tuinstra, M.R.; Prasanna, B.M.
Publication - Genetic trends in CIMMYT’s tropical maize breeding pipelines(Nature Publishing Group, 2022) Prasanna, B.M.; Burgueño, J.; Beyene, Y.; Makumbi, D.; Asea, G.; Woyengo, V.; Tarekegne, A.T.; Magorokosho, C.; Dagne Wegary Gissa; Ndhlela, T.; Zaman-Allah, M.; Matova, P.M.; Mwansa, K.; Mashingaidze, K.; Fato, P.; Chere, A.T.; Vivek, B.; Zaidi, P.; Vinayan, M.T.; Nagesh, P.; Rakshit, S.; Kumar, R.; Jat, S.L.; Singh, S.B.; Kuchanur, P.; Lohithaswa, H.C.; Singh, N.K.; Koirala, K.B.; Ahmed, S.; San Vicente Garcia, F.M.; Dhliwayo, T.; Cairns, J.E.
Publication - 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 - Genotype-by-environment interaction effects under heat stress in tropical maize(MDPI, 2020) Vinayan, M.T.; Zaidi, P.; Seetharam, K.; Das, R.R.; Viswanadh, S.; Ahmed, S.; Miah, M.A.; Koirala, K.B.; Tripathi, M.P.; Arshad, M.; Pandey, K.; Chaurasia, R.; Kuchanur, P.; Patil, A.; Mandal, S.S.
Publication - Environmental variables contributing to differential performance of tropical maize hybrids across heat stress environments in South Asia(Southern Cross Publishing Group, 2019) Vinayan, M.T.; Zaidi, P.; Seetharam, K.; Md. Ashraful Alam; Ahmed, S.; Koirala, K.B.; Arshad, M.; Kuchanur, P.; Patil, A.; Mandal, S.S.Heat stress resilience in maize hybrids is emerging as an important trait in germplasm targeted for cultivation in the post-rainy season spring in South Asia. One of the major challenges in targeted breeding for these agro-ecologies is the differential response of maize genotypes to heat stress across locations during the spring season. This study is targeted at identifying the major environmental variables that contributed to the genotype × environmental (GEI) yield variations observed among genotypes grown in response to heat stress. The trial dataset used for this study constitutes 46 trials × location combinations spread over a period of three years (2013- 2015). Partial least square (PLS) regression analysis was implemented to decipher the important environmental variables contributing to the observed yield variation among maize trials planted during spring across locations of South Asia. The first two factors from the PLS study explained the 30 per cent yield variation across trials. The largest contributor of this variation was relative humidity (RH) and vapor pressure deficit (VPD) during flowering stage of the crop across the years.
Publication - Effects of temperature stresses on the resistance of chickpea genotypes and aggressiveness of Didymella rabiei isolates(Frontiers, 2017) Ahmed, S.; Sanae Krimi Bencheqroun; Hamwieh, A.; Imtiaz, M.Chickpea (Cicer arietinum L.) is an important food and rotation crop in many parts of the world. Cold (freezing and chilling temperatures) and Ascochyta blight (Didymella rabiei) are the major constraints in chickpea production. The effects of temperature stresses on chickpea susceptibility and pathogen aggressiveness are not well documented in the Cicer-Didymella pathosystem. Two experiments were conducted under controlled conditions using chickpea genotypes and pathogen isolates in 2011 and 2012. In Experiment 1, four isolates of D. rabiei (AR-01, AR-02, AR-03 and AR-04), six chickpea genotypes (Ghab-1, Ghab-2, Ghab-3, Ghab-4, Ghab-5 and ICC-12004) and four temperature regimes (10, 15, 20, and 25°C) were studied using 10 day-old seedlings. In Experiment 2, three chickpea genotypes (Ghab-1, Ghab-2, and ICC-12004) were exposed to 5 and 10 days of chilling temperature exposure at 5°C and non-exposed seedlings were used as controls. Seedlings of the three chickpea genotypes were inoculated with the four pathogen isolates used in Experiment 1. Three disease parameters (incubation period, latent period and disease severity) were measured to evaluate treatment effects. In Experiment 1, highly significant interactions between genotypes and isolates; genotypes and temperature; and isolate and temperature were observed for incubation and latent periods. Genotype x isolate and temperature x isolate interactions also significantly affected disease severity. The resistant genotype ICC-12004 showed long incubation and latent periods and low disease severity at all temperatures. The highly aggressive isolate AR-04 caused symptoms, produced pycnidia in short duration as well as high disease severity across temperature regimes, which indicated it is adapted to a wide range of temperatures. Short incubation and latent periods and high disease severity were observed on genotypes exposed to chilling temperature. Our findings showed that the significant interactions of genotypes and isolates with temperature did not cause changes in the rank orders of the resistance of chickpea genotypes and aggressiveness of pathogen isolates. Moreover, chilling temperature predisposed chickpea genotypes to D. rabiei infection; developing multiple stress resistance is thus a pre-requisite for the expansion of winter-sown chickpea in West Asia and North Africa.
Publication - Results of the 1st International Heat Stress Genotype Experiment(CIMMYT, 1992) Reynolds, M.P.; Acevedo, E.; Ageeb, O.A.A.; Ahmed, S.; Balota, M.; Carvalho, L.J.B.; Fischer, R.A.; Ghanem, E.; Hanchinal, R.R.; Mann, C.E.; Okuyama, L.; Olugbemi, L.B.; Ortiz-Ferrara, G.; Razzaque, M.A.; Tanndon, J.P.Fischer (1989) summarized the detrimental effects of high temperature on wheat growth as follows: Yield reduction can occur at temperatures above a mean as low as 150C, with the spike and grain growth phases being especially sensitive; and With very hot conditions during stand establishment, lack of full ground cover will further contribute to yield loss. Mechanistically, it seems that high temperatures affect a number of physiological processes, apart from rate of development (see Discussion), although causal links between these processes and yield loss in the field environment have not previously been well established. The interaction between these mechanisms and genotype form the basis of our investigations. Probably the greatest challenge in understanding the physiological problems associated with high temperature stress is to encompass the diversity of hot environments that exist. These can be put into four broad categories: Hot dry, Hot humid, Very hot dry, and Very hot humid. Hot and very hot are climates where the mean temperature for the coolest month of the cycle is greater than 17.5 and 22.50 C, respectively. Dry and humid are climates where the mean vapor pressure deficits are above and below 10 mb, respectively for the crop cycle (Fischer and Byerlee 1991). Since the experiments described in this special report have been conducted on a multilocational basis as a collaboration between CIMMYT and national programs in warm wheat growing environments (Table 1), we anticipate that our results will be representative of the range of warm climates that exist. The International Heat Stress Genotype Experiment (IHSGE) is designed to look closely at a small number of traits which, in preliminary studies at CIMMYT and in consultation with CIMMYT outreach staff and other researchers in hot environments, seem to have potential value as predictors of yield at high temperatures.
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