Person:
Joshi, A.K.

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Joshi
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Joshi, A.K.

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  • Introduction and exchange of improved bread wheat germplasm in the eastern gangetic plains of South Asia
    (Global Science Books, 2008) Ortiz-Ferrara, G.; Sharma, R.; Bhatta, M.R.; Gyanendra Singh; Pandit, D.B.; Joshi, A.K.; Siddique, A.B.; Duveiller, E.; Ortiz, R.
    Wheat (Triticum aestivum L.) yield must be increased in the Eastern Gangetic Plains (EGP) of South Asia to improve the livelihoods of poor farmers. The International Maize and Wheat Improvement Center (CIMMYT) and its partners in South Asia initiated a regional yield trial, the Eastern Gangetic Plains Wheat Yield Trial (EGPYT) in 2000 to identify wheat cultivars with high and stable grain yield, superior agronomic traits and disease resistance. Advanced breeding lines from CIMMYT, Mexico and wheat programs in the region were assembled each year and tested at key sites in Bangladesh, India and Nepal. A total of 168 experimental genotypes and four checks were tested over eight years (2000–2007). The wheat genotypes showed arrays of genetic variation in grain yield, days to heading, plant height, 1000-kernel weight (TKW), and spot blotch severity in the eight years. Several experimental genotypes were superior to checks in yield, TKW, spot blotch resistance in individual country and across the region. We identified two sets of superior lines across the region that could be used as parents (Parent 1 = ‘BL1804’, ‘BL1968’, ‘BL2324’, ‘G162/BL1316//NL297’, ‘NL750’, ‘NL835’ and ‘Shatabdi’; Parent 2 = ‘BL2966’, ‘Milan/Shanghai#7’, ‘NL966’, ‘PBW373’, ‘BL3122’, ‘BL3124’, ‘BL3191’ and ‘SW89.5124*2/Fasan’) to develop new improved lines with high grain yield and TKW, spot blotch resistance, early maturity and acceptable plant height. New cultivars have been developed through this effort, and many outstanding lines selected by wheat breeders in the region are being used as parents in the breeding programs of different centers. This regional effort has helped in the introduction and exchange of superior wheat genotypes, thus enriching the germplasm base in the region. The findings underline the importance of region-focused varietal testing approach in developing and disseminating high yielding wheat germplasm.
    Publication
  • Physiological and morphological aspects of bipolaris sorokiniana conidia surviving on wheat straw
    (Korean Society of Plant Pathology, 2002) Chand, R.; Singh, H.V.; Joshi, A.K.; Duveiller, E.
    Wheat samples showing typical spot blotch symptoms on stems and sheaths were collected from the field after physiological maturity, and were sealed in paper bags and stored in the laboratory at room temperature to study the survival of Bipolaris sorokiniana conidia on wheat straw. The materials were observed at monthly intervals to assess the conidia viability during storage. After 4 months, the frequency of individual conidia already present on wheat straw at the time of sampling was reduced and appeared to be progressively replaced by the formation of round structures consist-ing of conidia aggregates. After 5 months, distinct, individual conidia were no longer detected, and only 'clumps of conidia' were observed. These dark black aggregates or 'clumps of conidia’measured 157-170 μm in diameter and were grouped into boat-shaped olivacious conidia showing thick wall and measuring 50-82 × 20-30 μm. The germination was unipolar and below 0.5%, suggesting the occurrence of dormancy, In contrast, individual conidium produced on wheat during the growing season were 96-130 × 16-20 μm, slightly curved, hyaline to light pale, and euseptate with a bipolar germination reaching 98-100%. Bipolaris sorokiniana conidia produced on PDA were 55-82 × 20-27 μm, tapered at both ends, dark brown to olivacious, distoseptate, showed up to 1% germination, and were predominantly unipolar. Results of the present study suggest that B. sorokiniana conidia belonged to two different physiological categories corresponding to the pathogen's infection phase and its survival, respectively. The infection phase is characterized by a high germination percentage as opposed to the survival phase harboring apparent dormancy
    Publication