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INFLUENCE OF NIGHT TEMPERATURE ON MICROSPOROGENESIS AND MEGASPOROGENESIS IN SORGHUM BICOLOR (L.) MOENCH
Abstract
A greenhouse-growth chamber experiment was conducted in 1982 to investigate causes of seed-set reduction in RS 671 grain sorghum due to cooler (17 C) and elevated (29 C) night temperatures imposed for a week at floret differentiation (FD) and FD + 7 days compared to near optimum 23 C. Anatomical changes during microsporogenesis and megasporogenesis were studied. A significant reduction occurred in seed number/plant (68%) and grain yield/plant (64%) at 29 C when the treatment was imposed at FD. These parameters were significantly reduced at the cooler temperature only when treatments were imposed at FD + 7 days. Meiosis was normal in both the stresses during microsporogenesis and megasporogenesis. When cool temperature stress was applied at the FD stage events observed were premature cell vacuolation, microspore dissociation, heavy vacuolation in the tapetum at the late tetrad stage, callose ring formation aroung the tapetum, shrinkage in another cavity (14%) and 46% pollen sterility. Elevated temperature effects were similar but did not lead to callose ring formation around the tapetum. Shrinkage of the anther cavity was increased by 21% and the pollen sterility was much higher (60%). Treatment of FD + 7 days caused greater dissociation of nonvacuolate pollen, anther emptiness, hypertrophy and dilation of the tapetum, a 25% shrinkage increase in the anther cavity, and disorderly development of anthers (no anthers in 15%, 10% had 2 anthers, and 5% had 1 anther). Ovule abortion was evident in the cooler temperature (30%) and in the elevated temperature (33%) treatment at FD + 7 days. This was associated with separation of integuments at the micropylar end and the degeneration of nucellus at the chalazal end. An increase in poorly developed pistils and shrivelled stigmas by 34 and 20% was noticed in cooler and elevated temperatures, respectively. Formation of callose plugs (28%) in pollen tubes and callose deposition in pollen grains (68%) blocked fertilization in the higher temperature. A field experiment showed a significant increase in sterility at elevated temperature (Ambient + 12 C).
Subject Area
Anatomy & physiology
Recommended Citation
DHOPTE, ARVIND M, "INFLUENCE OF NIGHT TEMPERATURE ON MICROSPOROGENESIS AND MEGASPOROGENESIS IN SORGHUM BICOLOR (L.) MOENCH" (1984). ETD collection for University of Nebraska-Lincoln. AAI8423776.
https://digitalcommons.unl.edu/dissertations/AAI8423776