Small cbange3 in geography and topography can result in great differences in night temperature. Indeterminate soybeans (Glycine max (L.) Merr. 'S09-90') of Maturity Group 0 were grown under field conditions in 1981 and 1982 to assess the effect of low night temperature on growth and seed yield. The soil was a Woodburn silt loam (fine-silty, mixed, mesic Aquultic Argixerolls). Mean minimum night temperature treatments were: Check (uncontrolled, ca. 10°C), 16 ± 1 oc and 24 ± l"C. Elevated night temperatures were achieved
Crop over‐fertilization has economic and environmental consequences. Sugarbeet (Beta vulgaris L.) N fertilizer requirements could be lower than expected when planted after shallow rooted onion (Allium cepa L.). Sugarbeet was planted on an Owyhee silt loam (coarse‐silty, mixed, mesic Xerollic Durorthid) for 2 yr, where the previous onion crop had received 0, 60, 120, 240, and 480 kg N ha−1. Soil nitrate and ammonium were measured in 0.3‐m increments to 1.8 m deep after harvesting onion, and before and after growing sugarbeet. Nitrogen uptake by plant parts, and beet and sucrose yields, were measured. Averaged across years, sugarbeet recovered 336, 316, 338, 400, and 505 kg N ha−1 when N fertilizer of the previous onion crop was 0, 60, 120, 240, and 480 kg ha−1, respectively. The corresponding reduction in available inorganic N from the top 1.8 m of the soil during sugarbeet growth was 27, 82, 62, 120, and 152 kg ha−1. Nitrogen recovered by sugarbeet was largely supplied by sources other than preplant available N. Recovered sucrose yield was near maximum when the N rate on the previous onion crop was 240 kg ha−1, which resulted in preplant NO3–N levels of about 70 kg ha−1 in the top 0.6 m of the soil. Sucrose yield did not improve when petiole NO3–N in late June exceeded 6 g kg−1. In conclusion, sugarbeet may not require fertilizer N when grown after onion fertilized with about 240 kg N ha−1
Dry matter allocation, and thus productivity, within soybean plants (Glycine max (L.) Merr.) is affected by night temperature. The indeterminate soybean cultivar S09‐90 of Maturity Group O was grown in the field at Oregon State University in 1981 and 1982 to assess the effect of night temperature on dry matter partitioning and seed growth through out the growing season. Mean minimum night temperature used as treatments included check (noncontrolled, ca. 10°C), 16, and 24°C. Night temperatures for 16 and 24°C treatments were raised by enclosing plots with polyethylene‐covered chambers at night and increasing chamber temperature with electric heaters. The chamber covers were removed each morning to provide natural field conditions during the daylight hours. Treatments were applied from 2 weeks after crop emergence until physiological maturity. Higher night temperatures enhanced early vegetative growth, advanced reproductive development and physiological maturity, and increased seed yield. Although higher night temperatures increased crop growth rate during the vegetative period, final vegetative dry matter, pod weight, and leaf area generally decreased as night temperature increased. Net assimilation rates were similar among the treatments. Seed growth duration (SGD) did not vary considerably among the treatments except for 24°C plants in 1982 whose SGD was 6 days longer than the check plants. Increased seed yield of the 16°C plants over the check was associated with 31 and 38% increases in seed growth rates (SGR) in 1981 and 1982, respectively. Seed growth rate of 24°C plants also was 24% higher than the check in 1981. Increased seed yield of 24°C plants in 1982 was primarily due to their longer SGD. Increased seed growth along with reduced vegetative growth and pod wall growth of plants at higher night temperatures resulted in higher harvest indices in these plants compared to the check. Harvest index was increased above the check by 27 and 33% in 1981 and 16 and 23% in 1982, for 16 and 24°C plants, respectively. These data support the conclusion that SGR of early maturing soybeans is responsive to night temperatures. Low night temperatures restrict SGR that, in turn, favors partitioning of photosynthates to vegetative organs and pod walls.
Potential growth of poplar (Populus deltoidesP. nigra.) is highly dependent on the amount of applied irrigation and soil moisture. Hybrid poplar (cultivar OP-367) was planted at 222 trees/ac in April 1997 at the Oregon State University Malheur Experiment Station near Ontario, OR. Six irrigation treatments included a combination of soil water potentials as thresholds for initiating irrigation and varying water application rates. Water was applied via micro-sprinklers installed along the tree rows. Results indicated that for optimum poplar growth, soil water potential at an 8 in. depth should average above -20 kPa (kPa = cbar) during the growing season. This was achieved by irrigating when the soil water potential reached -25 kPa and applying 21 ac-in./ac of irrigation water during the first year, 35 ac-in./ac during the second year, and 44 ac-in./ac during the third year. By the end of the third year, trees receiving optimum irrigation averaged 26 ft tall and produced 256 ft3 of wood/ac. West. J. Appl. For. 17(1):46–53.
Knowledge of phenological development in crops as a function of environmental variables can be useful in crop improvement and management. Night temperature is an environmental factor affecting soybean [Glycine max (L.) Merr.] phenology. The objective of this experiment was to determine if accumulated heat units can be used to predict stages of reproductive development (SRD) in soybean grown under different night temperatures. Field experiments were conducted at Oregon State University and the University of Minnesota in 1984, 1985, and 1986. Twenty soybean genotypes of Maturity Groups (MG) 000, 00, and 0 of different origins were grown at Corvallis, OR and St. Paul, MN, which have mean minimum night temperatures of approximately 10 and 15 °C, respectively, during the summer months. Mean maximum temperatures for the same period of the year are similar for the two locations (ca. 26 °C). Both locations are at about the same latitude (ca. 45 °N). Dates for all SRD were recorded at both locations and accumulated heat units (using base and maximum temperatures of 6 and 30 °C, respectively) were calculated from emergence to each SRD for all genotypes. Locations were significantly different for heat units requirements for phenological development of soybean within all three MG. Genotypes within each MG were also significantly different. Location by genotype interaction was not significant. However, location by SRD, and genotype by SRD (except within MG 0) interactions were significant, while location by genotype by SRD interaction was not significant. The results indicate that night temperature has a significant effect on soybean phenology, but its relative effect varies at different SRD, and is genotype dependent. The results further suggest that a degree‐day model may be adequate to predict SRD in early maturing soybeans with the same adaptation characteristics only when grown at a fixed location for which the coefficients have been developed.
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