Corn Genotypic Variation Effects on Seedling Emergence and Leaf Appearance for Short-Season Areas

Identifying corn ( Zea mays L.) genotypes with faster rates of seedling emergence and leaf appearance is important in developing a corn crop with earlier canopy closure and better seasonal light interception. A greenhouse experiment was conducted twice to investigate whether corn genotypes known to vary in canopy architecture and yield potential differed in rates of seedling emergence and leaf appearance. The experiment was arranged in a randomized complete block design utilizing seven genotypes: five of the newly developed Leafy reduced-stature (LRS) types (LRS1, LRS2, LRS3, LRS4 and LRS5), one conventional type [Pioneer 3979 (P3979)], and one late-maturing big-leaf (LMBL) type. Five seeds were planted in each pot and seedling emergence was recorded every day until all seeds emerged. Leaf appearance was recorded from seedling emergence until the plants reached anthesis. There was variability among the genotypes for both seedling emergence and leaf appearance rate. Mean seedling emergence values of greater than 90 % were achieved by four of the five LRS genotypes, and the LRS types generally emerged more rapidly than the others. Leaf appearance rate showed linear increases over time; however, LRS genotypes (in particular LRS3, LRS4 and LRS5) had more rapid leaf appearance rates than the others. The LMBL hybrid ranked last for both seedling emergence (<80 %) and leaf appearance rate. Rapid seedling emergence and leaf appearance by early-maturing genotypes (LRS and P3979, especially LRS) may help these types of genotypes achieve earlier canopy closure and better use of the light available during the growing season, which is critical in a short growing season environment.     

Effects of controlled-release fertilizer on root and shoot growth of Cotoneaster divaricata Rehd. & Wils.

Semi-hardwood cuttings of Cotoneaster divaricata grown in 926 cm³-containers were top-dressed with controlled-release Osmocote (18.0 N-2.6 P-10.0 K) at levels of 0, 2, 3 or 6 g/l of container. Optimum shoot and root growth was obtained at 2 g/l. Applications of controlled-release fertilizer significantly increased foliar N and P concentration, but not foliar K. The most desirable shoot-to-root ratio occurred at 2 g/l.     

Effects of organic matter and controlled-release fertilizer on nutrient retention during intermittentmist propagation

Semi-hardwood cuttings of Ligustrum japonicum Thunb. and Juniperus conferta Parl. were propagated in sand or sand : peat (1 : 1 v/v) and top-dressed with osmocote controlled-release fertilizers at various rates. Soluble salts, NO^?₃, P and K leaching through media was greater in sand, especially with osmocote 14-14-14. Loss of P and K in both media was not as rapid as the loss of NO^?₃. The pH of leachate from sand : peat was significantly less than that from sand. The 18-6-12 osmocote provided steady nutrient release in both media.     

Copulatory vocalizations of chacma baboons (Papio ursinus), gibbons (Hylobates hoolock), and humans

The copulatory vocalizations of female baboons (Papio ursinus) are more complex than those of female gibbons (Hylobates hoolock) or human females. Adult males of all these species begin calling later than the female, but subordinate baboon males do not call. Copulatory vocalizations may serve to mutually stimulate the mating partners or to incite male competition.     

THE VISUAL ESTIMATION OF PASTURE AVAILABILITY USING STANDARD PASTURE CORES

A coring technique (6), that may be used for estimating the mean amount of herbage on closely grazed pastures, has been adapted to include visual scoring. Two methods are described, both of which use sets of pasture cores from the sward as reference standards. The observers score the herbage on view at random sites against the standards. In the first method the scores are converted to herbage yields directly by reference to the yields of the standards. In the second method a double sampling regression technique is used and the set of standards is used as a visual guide only.     

A yield-independent, 15N-isotope dilution method to estimate legume symbiotic dependence without a non-N2-fixing reference plant

The proportional contribution of atmospheric N₂ to the N nutrition of lupin (P _atm) was estimated in a field experiment following addition of NH₄Cl of KNO₃ to unconfined microplots (1.5 m²) at 2.5 g N m^-2 (10 atom% ¹⁵N). The integrated ¹⁵N enrichment, or mean pool abundance, of nitrate extracted from 0- to 15-cm samples taken under the lupin crop on eight occasion between 28 and 190 days after sowing was used as the reference criterion to estimate P _atm by the ¹⁵N-isotope dilution technique. Estimates of P _atm were similar to those obtained using canola as a non-fixing reference plant, but were higher than estimates obtained using a yield-dependent model. Use of mean pool abundance obviates the need for a non-fixing reference plant, and the frequent sampling and isotope-ratio analysis of the legume biomass required with the yield-dependent model is unnecessary. However, further work is needed to validate a sampling strategy commensurate with the growth of the legume roots.