Growth of Lotus creticus creticus and Cynodon dactylon under two levels of irrigation

Soils with scarce plant covering are very susceptible to water and wind erosion. Two species recommended for permanent cover of soil are Lotus creticus creticus and Cynodon dactylon. The performance of both species cultivated in pure stands and in mixture and with 2 watering regimes, high (12.64 L/bag) and low (8.36�L/bag), was analysed in polyethylene bags between March and July in greenhouse conditions. With low watering the growth of both species was lower but mortality of plants was not observed. Growth of stems in L.�creticus and stolons in C. dactylon did not stop with low watering. The growth of C. dactylon was higher than that of L. creticus at both watering regimes. Total root and green shoot biomass of each species was affected by watering. Green leaf area, root weight ratio, root hydraulic resistance, and watering efficiency (g biomass/L watering) differed with the combination of species. Green leaf area, root hydraulic resistance, and watering efficiency were higher in C. dactylon than in L. creticus. Root weight ratio was higher in L. creticus than in C. dactylon, but the specific length and area of roots were higher in C. dactylon than in L. creticus. Net photosynthesis rate of each species was only affected by watering regime. Performance of both species was not affected by the mixture and it has the potential to be a successful ground cover.

Needle-Clipping Longleaf Pine and Top-Pruning Loblolly Pine in Bareroot Nurseries

Studies have shown that clipping needles of longleaf pine before outplanting can increase average seedling survival by 13 percentage points. Under some situations, the increase in survival might be due to a reduction in transpiration. For loblolly pine, top-pruning in the nursery might increase average survival by 6 percentage points. Benefits of pruning appear greater when seedlings experience stress after planting and when nonpruned seedlings have low root weight ratios (root dry weight/total seedling dry weight). On some droughty sites, a seedling with a 0.3 root weight ratio might have an 80% chance of survival, while a seedling with a 0.2 root weight ratio might only have a 53% chance of survival. In most studies where heights were measured after 3 yr in the field, pruned seedlings were the same height as nonpruned seedlings (± 7 cm). South. J. Appl. For. 22(4):235-240.

Effect of Wind and Soil Moisture on the Growth of `Bluecrop' (Vaccinium corymbosum L.)

This study was conducted in the greenhouse by running two experiments at different temperature regimes (22°C day and 13°C night and 33°C day and 22°C night). One-year-old tissue culture propagated plants were irrigated at three different soil moisture tension levels (5, 15, and 30 cnbars) and either exposed to moving or still air. The moving air treatment was created by two 51-cm-diameter fans running at either low (5.6 mph) or medium (8.2 mph) speed. Each experiment included, forty-eight plants arranged in a randomized complete block design. Each block consisted of a greenhouse bench containing two fans, a plastic dividing wall and two plant replications for each treatment. Canopy volume measurements were taken at the beginning, middle and end of each experiment to estimate growth rate. At the end of each experiment, total leaf area and leaf, stem and root dry weight data were collected. In the moderate temperature experiment, the still air treated plants had the highest canopy volume and leaf weight ratio while the moving air treated plants had the highest stem weight ratio. The only difference for the moisture treatments was the 5-cnbar treatment had the highest canopy volume. In the high temperature experiment, the still air treated plants had the highest canopy volume, total leaf area, leaf dry weight, shoot/root ratio, leaf weight ratio and leaf area duration while the moving air treated plants had the highest root weight ratio. The 5-cnbar treatment had the highest canopy volume and biomass accumulations. The 30-cnbar treatment had the highest root weight ratio.