To achieve the stable supply of spinach for processing use, scheduled harvest based on growth prediction is effective. In this study, we investigated the effect of temperature and solar radiation on the dry matter production of spinach, and quantified the relationship. The leaf area index (LAI) was fitted with a logistic curve with integrated temperature as the explanatory variable. The fraction of radiation intercepted by the foliage was approximated by 1-exp(-0.69 × LAI) when LAI was below 3.26, and was constant at 0.89 in the higher LAI range. Average radiation-use efficiency was 0.98 g•MJ -1 , which was approximated by a logarithmic function with the mean temperature of the previous three days as the explanatory variable. The model constructed based on these relationships was validated using the growth data obtained in a different year. As a result, the logistic relationship between the integrated temperature and LAI was applicable for three data-sets obtained from cultivation tests with different planting dates. For a data-set in which early growth was retarded, minor adjustment of the integrated temperature improved the fit of the model. The correlation coefficient between estimated and observed dry matter production based on the modified model was 0.98.
R Re ev vi ie ew w a ar rt ti ic cl le e S Sh ho or rt t r re ep po or rt t Suzuki T, Kamada E, Ishii T 2019 Effects of ratoon harvesting on the root systems of processing spinach. Plant Root 13:23-28.
Abstract:The mechanical harvesting of processing spinach (spinach used in production of processed food) is potentially becoming a common practice in Japan. Root distribution affects water and nutrient absorption, but how the roots spread in the soil profile during the regrowth period of spinach remains unknown. In this study, we investigate the root systems of processing spinach in topsoil (5 and 15 cm deep) and deeper soil layers (25, 35, 45, and 55 cm deep) cultivated using ratoon harvesting system. The total root length densities (calculated using the average of the densities at 0 and 15 cm horizontal distance from the row for each depth) in the second harvest were more than two-fold greater than those in the first harvest. The root length percentage in the topsoil and root depth indexes indicate that root systems are in shallower soil layers at the second harvest than at first harvest.
Two field experiments were conducted using the sweet potato cultivar 'Murasakimasari' with both conventional vine planting (CVP) and tuber seedling transplanting (TST) to estimate yield properties under large ridge (LAR) cultivation with two rows in a ridge and compared with the conventional high ridge (CHR) cultivation method. The LAR shapes were LAR1 (ridge height [RH], 35 cm; ridge distance [RID], 180 cm; ridge bed width [RBW], 120 cm; ridge shoulder width [RSW], 90 cm; and furrow, 60 cm)
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