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  • Author or Editor: C.D. Stanley x
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Many factors contribute to final apple fruit size. Researchers have studied these factors and have developed models, some very complex. Results from many New Zealand regions over several years suggest that early season temperature along with crop load are the key factors driving final fruit size. Accumulated growing degree days from full bloom to 50 days after full bloom (DAFB), accounted for 90% of the variance in fruit weight of `Royal Gala' apples at 50 DAFB under nonlimiting low-crop-load conditions. In turn, fruit weight at 50 DAFB accounted for 90% of the variance in final fruit size at harvest under the low-crop-load conditions. We hypothesise that a potential maximum fruit size is set by 50 DAFB, determined by total fruit cell number, resulting from a temperature-responsive cell division phase. Under conditions of no limitations after the cell division phase, we suggest that all cells would expand to their optimum size to provide the maximum fruit size achievable for that cell number. Factors which affect growth partitioning among fruits, e.g., higher crop loads, would reduce final fruit size, for any given cell number, when grown in the same environment. In Oct. 1999, four different crop loads were established at full bloom on `Royal Gala' trees (M9 rootstock) in four climatically different regions. In Hawkes Bay, similar crop loads were established at 50 DAFB on additional trees. Hourly temperatures were recorded over the season. Fruit size was measured at 50 DAFB and fruit will be harvested in Feb. 2000. These data should provide fresh insight and discussion into the respective roles of temperature and competition during the cell division fruit growth phase on apple fruit size.

Free access
Authors: and

The use of the recently developed fully-enclosed seepage subirrigation system for fresh market tomato production has demonstrated an improved ability to maintain a water table at a desired level (when compared to conventional ditch-conveyed seepage subirrigation) by means of more precisely controlled application and a greater uniformity throughout the field. This is achieved through use of microirrigation tubing rather than open ditches to convey water to raise the water table to desired levels. When manually controlled, the system has shown to save 30-40% in irrigation amounts primarily due to almost total elimination of surface runoff. An automated control system was designed and evaluated with respect to practicality, durability, and performance of various designs of level-sensing switches. The advantages and limitations of the designs in relation to water table control for tomato production will be presented.

Free access

Abstract

An easy method to estimate water requirements for poinsettia (Euphorbia pulcherrima Willd. ex Kl.) production with practical applications to commercial operations was developed to promote water conservation. A water-requirement prediction equation (P ≥ 0.01, R 2 = 0.78) that used pan evaporation along with plant-canopy height and width as input variables was generated. Equation verification was carried out by comparing plant quality of crops irrigated according to the generated water-requirement prediction equation to crops irrigated “on-demand” or with capillary-mat irrigation. Plants irrigated with the prediction equation were smaller than plants grown with capillary mat, but plant quality ratings for ‘Annette Hegg Diva’ and ‘Dark Red Annette Hegg’ were not significantly different. ‘Gutbier V-10 Amy’ plants grown with irrigation on-demand were of higher quality than plants grown using either the capillary mat or the prediction equation. Applied water was significantly lower for plants irrigated with the prediction equation than would normally be applied in a commercial operation using a conservative fixed daily irrigation rate.

Open Access

Abstract

Daily water use for potted Chrysanthemum ×morifolium Ramat. ‘Spirit’ was estimated from pan evaporation and plant height data collected over 2 seasons using 3 different growing environments (glass greenhouse, saranhouse, and outside—no structure). Regression equations derived using pan evaporation and plant height were not significantly improved with the inclusion of plant width as an additional variable to estimate water use.

Open Access

Abstract

Glyphosate at rates found adequate (3.36 kg/ha) for orchard weed control is phytotoxic and possibly fatal to young apple trees if it is intercepted by the tree’s foliage in sufficient quantities. Its use appears safe, however, if precautions are used to avoid this contact. Following foliage absorption, the glyphosate is translocated to active growing points resulting in leaf attenuation and cupping and necrosis to leaves, terminals, and trunks.

Open Access

Abstract

Leaf water potential (LWP) data for cut-flower chrysanthemums (Crysanthemum morifolium Ramat.) collected from 5 different irrigation rate treatments throughout the growing season were compared to the final plant characteristics and yield in order to evaluate the usefulness of LWP for estimating water stress effects on ultimate yield. Significant treatment differences for LWP response measured during high evaporative demand periods were similar to treatment differences for yields and final plant characteristics. Treatment differences for LWP response measured during low evaporative demand periods were not significant and did not reflect the significant treatment differences for yields and final plant characteristics. Results indicate that LWP measurements vary with changes in atmospheric conditions, such as cloud cover, and are difficult to interpret relative to water stress effects on final plant characteristics. Plant growth parameters, such as height or growth rate, when monitored during the season, were found to be more adequate indicators of stress effects on final yield.

Open Access

Abstract

The numbers of twospotted spider mites (Tetranychus urticae Koch) per unit of leaf area on ‘Manatee Yellow Iceberg’ chrysanthemum (Chrysanthemum X morifolium Ramat.) grown with 13.6, 20.3, 27.1, 33.9, or 40.7 cm of water during the crop cycle were inversely related to amounts of water provided on both of 2 sampling dates. The numbers of mites per leaf were inversely related to amounts of water provided on the first of the 2 sampling dates. There was no significant response of leafmine densities with various amounts of water provided.

Open Access

Abstract

The minimum water requirement to produce the greatest number of marketa- bie cut flowers of Chrysanthemum × morifolium Ramat. ‘Manatee Yellow Iceberg’ was 35 cm with trickle irrigation, a 91% reduction in water uses as compared to overhead irrigation systems. Linear responses for fresh weight, dry weight, leaf area, leaf number, and flower number between 13.6 and 40.7 cm of water supplied during production indicated that an additional 6 cm of water would improve marketable stem's quality.

Open Access

Abstract

Damage by leafminer [Liriomyza trifolii (Burgess)], increased linearly as leaf nitrogen increased from 2.2% to 4.0% in spring and fall plantings of Chrysanthemum x morifolium Ramat. ‘Manatee Yellow Iceberg’. The number of marketable stems was related quadratically to leaf nitrogen with maximum yields estimated to occur at 3.6% at harvest.

Open Access