A data base was generated for quantifying effects of thermal time (degree-days) on the appearance of new leaves, the expansion of such leaves to maximum area, their death, the appearance of new internodes below the node associated with such leaves, and the extension of these internodes to maximum length. The data base for a list of crop (agronomic and horticultural), weed, and native Tallgrass Prairie plants has been summarized, with equations for the above events as a function of degree days, with appropriate base temperatures and maximum cut-off temperatures, in a Java applet which is available at a website with the URL <http://th190-50.agn.uiuc.edu>. Associated graphical plots such as shown in this paper are also given. Branching behavior was accounted for. These events predict the effect of thermal time on leaf age and its height in the plant canopy, both important factors needed for upscaling functions for leaf behavior to those for behavior of the plant canopy. The data base is evolving to include coefficients for other species. Coefficients are used to predict the leaf area index of the canopy, which is important for predicting evapotranspiration from the crop and the protection of the soil from erosion. and X. Pan ... [et al,].
Field experiments were conducted under rain-fed conditions to study the growth and photosynthetic efficiency of transgenic Bt cotton hybrids during 2002-03 and 2003-04 seasons. Three Bt cotton hybrids (Bollgard 1) and their non-Bt (NBt) counterparts viz. MECH 12, MECH 162, and MECH 184 were grown along with a local hybrid NHH44. Growth parameters such as plant height, main-stem nodes, biomass accumulation, and physiological processes like stomatal conductance (gs), and rates of transpiration (E) and photosynthesis (PN) did not differ significantly between Bt and NBt hybrids up to 80 DAS (d after sowing). Squaring commenced at 50 DAS both in Bt and NBt. The loss of young fruiting forms by the entomological factors was three times less in Bt than NBt. As a consequence, Bt had more early formed bolls on the lower canopy which contributed to higher biomass and seed cotton yield. On the other hand, bolls distributed intermittently in NBt. Heavy boll load altered the growth and physiological processes, and as a result Bt had higher gs, E, and PN than NBt. Since developing bolls (sink) divert the saccharides and nutrients from other organs, Bt plants with heavy boll load senesced early and stopped the production of new squares and bolls. Thus, the boll load influenced the change in growth and physiological processes of Bt from NBt. and K. B. Hebbar, N. K. Perumal, B. M. Khadi.