No description available.

No description available.

No description available.

No description available.

Maize production in short-season environments has at least two critical problems. Firstly, maize grown in short-season areas has lower leaf area indices (LAI) than maize grown in long season areas, due to shorter plant stature and less time for development, which results in reduced leaf number and size. Secondly, in very short-season areas the seasonal thermal-time available may be insufficient to mature grain of current maize hybrids. Therefore development of maize types that accumulate leaf area and mature quickly would increase production of maize in mid- to short-season areas. The leafy (Lfy1) and reduced-stature (rd1) genes make contributions to this end. However, these two genes have not previously been combined. From 1991 to 1993, field experiments were conducted to evaluate the leafy reduced-stature (LRS) inbred lines and hybrids for yield, maturity times and morphological traits, at different planting densities and patterns in Montreal and Ottawa. LRS maize inbred lines showed the most rapid silk extrusion, optimum leaf area development, and rapid growth of the first ear, the highest yield per unit leaf area, and the closest synchronization of pollen shed and silk extrusion at high plant population densities. LRS maize hybrids had the most rapid leaf development, longest grain filling period, lowest grain moisture content at harvest, and highest harvest index. Therefore LRS hybrids should allow an extension into shorter season areas where it can not now be successfully cultivated, and may increase yields in mid- to short season areas where maize is now produced.

No description available.

Many factors are known to influence crop yields. Thus two of the basic plant growth requirements in the environment, namely, light and heat need be available to crop plants in specified quantities and/or qualities for good crop yields. In normal farm practice these two environmental factors are managed by proper cultural practices of the crops concerned. [...]

No description available.

No description available.

Two experiments were conducted between 1983 and 1985. In each case, timothy was established with or without barley, red clover, broadleaf weeds and grassy weeds. Four and six weeks after seeding, botanical composition, soil water-content, soil nutrient-content, light interception, and plant coverage data were obtained. The plots were then harvested once during establishment year and twice during subsequent years. At harvest, yield, botanical composition, and forage quality were obtained. Companion-cropping precluded forage cut during establishment and decreased forage yield during the first production year. Establishment with barley had little effect on forage quality but it favored the development of perennial broadleaf weeds. Inter-cropping with red clover decreased timothy yield but total forage production was increased and forage quality was improved. Red clover also reduced the development of perennial broadleaf weeds. The absence of broadleaf weed control increased productivity during establishment but timothy contribution was reduced and perennial broadleaf weeds development was accelerated. Perennial broadleaf weeds reduced yields during the first production year. Establishment without grassy weed control increased yield during establishment (but quality was lessened) and reduced it during the first production year. Establishment with grassy weeds had little effect on the weeds growing thereafter. In presence of both types of weeds, the grassy species were suppressed and the results reflected the situation observed in presence of broadleaf weeds. Finally, principal component analyses showed 12 factors that could be used to predict crop yield. The interpretation suggested that early measurements of weed density along with weed and crop coverage data would give good predictions of crop loss.