Average Tc Research Articles

The synthesis of technetium(V) complexes containing sterically bulky thiolate ligands. The molecular structure of tetrabutylammonium oxotetrakis(2,4,6-trimethylbenzenethiolato)technetate(V)

The reactions between [TcOCl 4] − and the sterically bulky thiols ArSH (Ar = 2,4,6-Me 3C 6H 2, 2,4,6- Pr i 3C 6H 2 and 2,6-Ph 2C 6H 3) in methanol afford complexes of formula [TcO(SAr) 4] − which may be isolated as salts with bulky organic cations. The molecular structure of [Bu n 4N][TcO(2,4,6-Me 3C 6H 2S) 4] was determined by X-ray diffraction methods. The Tc(V) centre was found to adopt the expected square pyramidal geometry in which an oxo group occupies the apical site and the four thiolate sulphurs the basal sites. The TcO distance is 1.659(11) Å and the average TcS distance 2.38(2) Å. The average cis STcS, trans STcS and OTcS angles are respectively 82.7(6)°, 138.4(3)° and 110.8(4)°.

Transpirational Cooling as a Screening Technique for Drought Tolerance in Oil Seed Brassicas

Twenty-two genotypes of five Brassica species (oilseed rape and mustard), consisting of two different maturity groups and differing in plant morphology, were grown on sandy soil without post-sowing irrigation during 1982–83 winter season. Canopy temperature (Tc minus air temperature (Ta, stomatal conductance ($) and osmotic adjustment were studied on two different dear days corresponding to the siliqua formation stage in early duration (137–150 d) and late maturing genotypes (151–165 d) of oilseed Brassicas. The absolute mid-day values of transpirational cooling (Tc–Ta) were relatively higher in B.juncea and B. carinata than in B. tomifortii, B. napus and B. campestris. Tc-Tm showed a genetic variability ranging from 0-5 to 4 °C for early maturing genotypes, and from 0–5 to 5 °C for late maturing genotypes. Mid-day Tc–Ta showed significant positive correlation with Kh osmotic adjustment and seed yield in Brassica cultivars. Early genotypes out-yielded the late maturing ones, despite the lower values of AT, and Tc–Ta at siliqua formation in the former rather than later group of cultivars. It is suggested that average mid-day Tc–Ta as observed with an infrared thermometer, could effectively be used as a technique to screen Brassica genotypes for drought tolerance under receding soil moisture conditions.

Leaf and Canopy Temperatures of Pearl Millet Genotypes under Irrigated and Nonirrigated Conditions1

AbstractIt has been reported from previous research that leaf and canopy temperatures correlate with the level of water stress in a plant. If genotypes of a given species differ in their response to water stress, then leaf and canopy temperatures could serve as indices of their drought resistance. To test this hypothesis, 10 pearl millet (Penniserum americanum (L.) Leeke) genotypes differing in plant morphology were grown on a Eudora silt loam soil (fine silty, mixed, mesic, Pachic Haplustoll) under both irrigated and nonirrigated conditions. Leaf temperature (Tl), canopy temperature (Tc), canopy minus air temperature (Tc – Ta), leaf‐water potential (Ψl), leaf‐diffusion resistance (LDR), water use (WU), and crop yields were observed in both irrigated and nonirrigated treatments. Significant differences (P<0.05) were found in the grain yield, Tc, and Tc – Ta of genotypes, only in the irrigated treatment. Grain yield was negatively and significantly correlated with average afternoon Tc(r = −0.81) and average afternoon Tc – Ta(r = −0.78). Grain yield ratio (nonirrigated grain yield/irrigated grain yield) was positively and significantly correlated with average afternoon Tl(r = 0.64), average afternoon Tc(r = 0.64), and average afternoon Tc – Ta(r = 0.75). In the nonirrigated treatment, however, correlations of grain yield and grain yield ratio with various stress indices were nonsignificant. Average afternoon Tc and Tc – Ta was significantly correlated with average afternoon LDR only in the irrigated treatment. This study suggests that average afternoon Tc and Tc – Ta as observed in a nonstressed environment with an infrared thermometer could effectively be used as a technique to screen millet genotypes for their grain yield and grain‐yield stability (nonirrigated grain yield/irrigated grain yield).