| A representative sample (Table 1) of the wild
and primitive wheat collection at the University of California at Riverside
was obtained through the kind courtesy of Dr. B .L. JOHNSON. The accessions
were grown at Gurdaspur in Rabi 1980-81 for screening against yellow
and brown rusts. The plot consisted of single one metre row. A row of infector
line containing a mixture of Agra Local and Kalayansona varieties was provided
all around the field. A majority of the collections were found to be very poorly adapted probably because of their higher vernalization and longer photoperiod requirements. None of the T. urartu lines flowered at Gurdaspur. Most of the T. boeoticum, T. monococcum and T. araraticum collections flowered very late in the season in the middle of April. There was either a very poor seed set or the grains shrivelled in the early stages of development. All T. dicoccoides and a few T. araraticum and T. monococcum collections flowered timely Artificial vernalization at 4C for 6-8 weeks and longer photoperiod (12-16 h) might help the wild wheats to flower timely for good seed set and for crossing them with spring and durum wheats. Well spread rains and suitable temperature in the season at Gurdaspur favoured maximum development of yellow and brown rusts of wheat. The rust data was recorded at the time of maximum appearance of each rust. The accessions with immune to traces of rust reactions were designated as resistant (R) while with reactions from traces to 100S were marked as susceptible (S). Stem or black rust appeared only in traces, and hence the data was not recorded. Yellow rust A majority of the accessions of wild diploid wheats T. boeoticum from Turkey. Iraq and Iran were resistant to yellow rust (Table 1). Out of 18 accessions of T. urartu from Lebanon 14 were resistant. Cultivated diploid wheat, T. monococcum from Turkey, USSR and various other countries showed excellent resistance. Accessions of wild tetraploid wheat T. araraticum from Iraq were also free from yellow rust. T. dicoccoides from Turkey, Iraq and Israel were highly susceptible and succumbed to yellow rust before the boot stage. Only a few accessions of , T. dicoccoides from Lebanon and Israel were found to be resistant. The only accessions of T. timopheevi and T. zhukovskyi were free from rust. Brown rust Only a few accessions of T. boeoticum from Turkey, Iraq and Iran were susceptible to grown rust while others were resistant.(Table 2). Among T. urartu collections from Lebanon, about 50% were resistant to brown rust. Again T. monococcum lines from Turkey and other countries were immune to brown rust. Triticum araraticum collections were both resistant and susceptible. Out of 72 collections of T. dicoccoides from Turkey, Iraq, Iran, Lebanon, Israel and other countries, 66 were susceptible while only two were resistant. T. timopheevii and T. Zhukovskyi were again resistant. Primitive wheats accessions of G 524 and G 1569 (T. aestivum spp. spetla) and G 532 (T. aestivum spp. macha.) were also susceptible to brown rust. Leaf Pubescence It is generally believed that leaf pubescence provides protection to the plants against insect-pest attack but its role in protection against rusts is not reported anywhere. Collections of T. boeoticum, T. araraticum, and T. dicoccoides had pubescent as well as glabrous leaves and leaf sheaths while T. monococcum and T. urartu had only glabrous leaves and sheaths. Accessions with and without pubescence were equally susceptible to both rusts indicating that pubescence afforded little or no protection against rusts. |
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