RA 00048.pdf - OAR@ICRISAT

sources of P. Plants grown with calcium phosphate compounds produced as much or more dry matter as plants
grown with KH 2 PO 4 in nutrient solutions, but less when grown in soils. Plants grown with ferric, ferrous, and aluminum
phosphates produced the least dry matter in both nutrient solutions and in soils. Widest differences among
genotypes for dry matter yields were noted for plants grown with ethylammonium phosphate, calcium tribasic
phosphate, glycerylphosphate,and KH 2 PO 4 . Plants grown with KH 2 PO 4 and calcium tribasic phosphate had nearly
6-fold higher dry matter produced per unit P than plants grown with ethylammonium phosphate. Genotypes showed
few differences in P distribution between roots and tops, but differed extensively in P distribution among lower,
middle, and upper leaves. Of the genotypes studied, BB-9040 was the most tolerant to low P and SC-33-9-8-E-4 was
the least tolerant.
Acetylene Reduction Activity of Several Sorghum and N 2 -Fixing
Bacterial Associations
S. C. Schank, Rax L. Smith, and J. R. Milam
Abstract
Fifty-one Sorghum vulgare (L.) Moench lines were tested in replicated field plots for acetylene reduction (AR). Range
of AR activity was from 0 to 1934 nanomoles per gram of dry root per hour. In order to further study these highly
variable field responses, an in vitro screening technique has been developed to evaluate plant responses, root bacteria
associations, and acetylene reduction of specific grass bacteria combinations. Axenic systems using diverse sorghum
germplasm were established by inoculating sorghum plants with Azospirillum or other N 2 -fixing bacteria. The
seedlings were grown in test tubes for 10 days on a Fahraeus, nitrogen and carbon free medium. In addition, bacterial
populations of Azospirillum were studied at the end of the growth period using fluorescent antibody labeling. Roots
were scored for root-bacteria associations. Photos of the root-bacteria associations will be displayed.
Embryo and Endosperm Formation in Cross-Sterile Facultatively
Aposporous Apomicts
M. Bharati, U. R. Murty, and N. G. P. Rao
Abstract
Twenty-one cross-sterile cultures were isolated in advanced generation progenies of crosses involving the facultative
apomict R-473, and a sexual line, White Seed. Four of these cross-sterile lines were examined at various time
intervals up to 4 days. A considerable number of embryo sacs remained unfertilized at various time intervals. Lack of
fertilization was concluded from the presence of intact synergids, unfused polar nuclei of the central cell and the
undivided egg. The frequency of such embryo sacs approached 20%. The unfertilized egg was seen to give rise to an
embryo starting from the 2nd day after pollination. Endosperm also formed simultaneously, but the endosperm nuclei
presented an appearance different from that of sexually formed endosperm. The antipodal nuclei were seen to have
contributed to such endosperm at least in some cases. Pollen tubes were found to continue growth in nuceli that were
more than 3 days old. Thes6 observations were taken to indicate that pollen tubes cannot penetrate aposporous
embryo sacs and that embryo and endosperm in such embryo sacs occurred autonomously a few days after anthesis.
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