Search Results
Abstract
We studied the horizontal and vertical root distribution of 3-year-old ‘Climax’ rabbiteye blueberry (Vaccinium ashei Reade) in a sandy loam soil. Root density decreased logarithmically in the horizontal direction from the crown and linearly with depth. Ninety percent of the roots were within 0 to 0.38 m from the crown and 0 to 0.45 m depth. Roots spread more within the rows than across rows. Sawdust mulch increased the radial spread of roots, but did not promote rooting in the top 0.15 m of soil. Compared to one or two drip emitters per plants, low-volume spray emitters increased radial spread of roots, but only in combination with mulching. Greatest vertical rooting occurred with a single emitter at the base of the plant without mulch. Emitters placed 0.46 m from the crown of the plant did not help the spread of roots towards these emitters.
Current methods of making crop cover estimates are time-consuming and tend to be highly variable. A low-cost, digital, red/near-infrared band ratioing camera (Dycam Inc., Chatsworth, Calif.) and accompanying software (S. Heinold, Woodland Hills, Calif.) were evaluated for estimating crop cover. The camera was tested using a set of images having leaf areas of known sizes with different crop, soil, and lighting conditions. In the field, camera-based crop cover estimates were compared to light bar measured estimates. Results indicate that the camera and image analysis software are capable of estimating percent crop cover over a range of soil, crop, and lighting environments. Camera-based crop cover estimates were highly correlated with light bar estimates (tomato r 2 = 0.96, cotton r 2 = 0.98). Under the conditions tested, the camera appears to be a useful tool for monitoring crop growth in the field.
Abstract
‘Tifblue’ and ‘Delite’ rabbiteye blueberry (Vaccinium ashei Reade) plants were grown for 4 years with or without mulch, with cultivated or sodded row middles, and under various irrigation treatments [one drip emitter at the base of the plant, two drip emitters 46 cm on either side of the plant, or a 40° or 360° low-volume spray emitter (LVSE) placed midway between plants]. Plant establishment and growth were optimal with 360° LVSE. Differences between irrigation treatments were minimized with mulch. Mulch increased growth of drip-irrigated but not of LVSE-irrigated plants and increased the yield of two-emitter and 360° LVSE-irrigated plants but not of one-emitter or 40° LVSE-irrigated plants. Treatment effects on growth were more apparent in the early establishment phase than in the 4th year of growth and with ‘Tifblue’ than ‘Delite’. Frost damage on ‘Delite’ was reduced by mulch. Vegetative bud development in the spring and fruit maturity were usually delayed on plants grown between sodded alleys or with mulch. Leaf drop in the fall was also delayed by mulch.
Abstract
The response of rabbiteye blueberry plants (Vaccinium ashei Reade) to rates and modifications of deep well water (pH 8.7) containing 0.695 dS·m-1 electrical conductivity (EC), a sodium adsorption ratio (SAR) of 29.7, and a bicarbonate concentration of 7.89 meq·liter-1 was compared to plants irrigated with rain and surface waters applied to 3 soils in a glasshouse-container study. Fresh weight increase and root fresh and dry weight were greater on plants irrigated with rainwater or pond water compared to plants irrigated with different rates of deep well water, or deep well water modified by the addition of gypsum or acidified with H2S04. Fresh weight increase, root fresh and dry weight, leaf fresh weight, and top:root ratios were higher on a loamy sand soil than on sandy loam or clay loam soils. Plant weight gain was positively correated with the percentage of sand, and negatively correlated with the percentage of clay and saturation-extract SAR. An increase in soil pH resulted from irrigation with deep well water which, along with its modifications, resulted in increased leaf Na and decreased leaf Ca and Mn, compared to rain or surface-water irrigations, which slightly lowered soil pH.