Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is directly related to potassium (K)-mediated phloem transport of sucrose into the fruit. However, during fruit growth and maturation, soil fertilization alone is often inadequate (due to poor root uptake and competitive uptake inhibition from calcium and magnesium) to satisfy the numerous K-dependent processes, such as photosynthesis, phloem transport, and fruit growth. Experiments were conducted during Spring 2003 and 2004 to determine if supplemental foliar K applications during the fruit growth and maturation period would alleviate this apparent inadequate K availability in orange-flesh muskmelon `Cruiser'. Plants were grown in a greenhouse and fertilized throughout the study with a soil-applied N-P-K fertilizer. Flowers were hand pollinated and only one fruit per plant was allowed to develop. Starting at 3 to 5 days after fruit set, and up to 3 to 5 days prior to fruit maturity (full slip), entire plants, including the fruit, were sprayed with a glycine amino acid-complexed potassium (potassium metalosate, 24% K) solution, diluted to 4.0 mL·L-1. Three sets of plants were sprayed either weekly (once per week), biweekly (once every 2 weeks) or not sprayed (control). Fruit from plants receiving supplemental foliar K matured on average 2 days earlier than those from control plants. In general, there were no differences in fruit maturity or quality aspects between the weekly and biweekly treatments except for fruit sugar and beta-carotene concentrations, which were significantly higher in the weekly compared to the biweekly or control treatments. Supplemental foliar K applications also resulted in significantly firmer fruit with higher K, soluble solids, total sugars, ascorbic acid (vitamin C) and beta-carotene concentrations than fruit from control plants. These results demonstrate that carefully timed foliar K nutrition can alleviate the developmentally induced K deficiency effects on fruit quality and marketability.

We report on the relationship between growth, partitioning of shoot biomass and hydraulic development of Eucalyptus tereticornis Sm. grown in glasshouses for six months. Close coordination of stem vascular capacity and shoot architecture is vital for survival of eucalypts, especially as developing trees are increasingly subjected to spasmodic droughts and rising atmospheric CO2 levels. Trees were exposed to constant soil moisture deficits in 45 L pots (30–50% below field capacity), while atmospheric CO2 was raised to 700 μL CO2 L–1 in matched glasshouses using a hierarchical, multi-factorial design. Enrichment with CO2 stimulated shoot growth rates for 12–15 weeks in well-watered trees but after six months of CO2 enrichment, shoot biomasses were not significantly heavier (30% stimulation) in ambient conditions. By contrast, constant drought arrested shoot growth after 20 weeks under ambient conditions, whereas elevated CO2 sustained growth in drought and ultimately doubled the shoot biomass relative to ambient conditions. These growth responses were achieved through an enhancement of lateral branching up to 8-fold due to CO2 enrichment. In spite of larger transpiring canopies, CO2 enrichment also improved the daytime water status of leaves of droughted trees. Stem xylem development was highly regulated, with vessels per unit area and cross sectional area of xylem vessels in stems correlated inversely across all treatments. Furthermore, vessel numbers related to the numbers of leaves on lateral branches, broadly supporting predictions arising from Pipe Model Theory that the area of conducting tissue should correlate with leaf area. Diminished water use of trees in drought coincided with a population of narrower xylem vessels, constraining hydraulic capacity of stems. Commensurate with the positive effects of elevated CO2 on growth, development and leaf water relations of droughted trees, the capacity for long-distance water transport also increased.

Some Perspectives on Rocket as a Vegetable Crop: A Review Baby leaf rocket is consumed worldwide as a salad vegetable. It is usually mixed with other baby leaf crops, such as spinach and lettuce, to form a mesclun-type salad. Rocket crops have become popular due to their distinct taste and textural appearance in mixed salads. There are two common forms of rocket that are commercially cultivated, a perennial species (Diplotaxis tenuifolia (L.) DC.) known as perennial wall rocket and an annual species (Eruca sativa Mill.) known as annual garden rocket. The popularity of baby leaf crops has increased in recent years due to consumer demand for a convenient, nutritious and easily accessible product. The baby leaf salad sector is now a significant part of the leafy vegetable market, with growth in this sector estimated to continue. The leaves of cultivars of perennial wall rocket and annual garden rocket have been bred to look similar, allowing for a year-round supply of produce. Despite this, there are many differences between the species that affect their responses to abiotic factors during growth and storage. This paper aims to provide some perspectives on the historical importance, botanical classification and cultivation techniques of these economically important plants.

Various source–sink perturbations were employed to alter partitioning to orange flesh melon (Cucumis melo L. reticulatus group) and thus to influence fruit biomass and soluble sugar content (indexed as total soluble solids of fruit juice, % TSS), with attention given to the timing of treatment application. A strong relationship existed between harvest index and fruit mass (r2 = 0.88) in control plants, whereas the correlation with fruit TSS was poor (r2 = 0.11). Augmentation of assimilate supply to fruit early in fruit development (before approx. 21 days before harvest, DBH) resulted in more fruit set and increased fruit biomass, whereas augmentation after 21 DBH resulted in increased fruit TSS. Thus, fruit biomass was increased (1644 cf. 1442 g FW per fruit for control, P = 0.02), but not TSS, on plants in which fruit set was delayed (source biomass increased, harvest index decreased from 59% for control to 38%). Treatment of plants with a cytokinin-based vegetative growth inhibitor at 14 DBH produced fruit with higher TSS (11.3 cf. 10.7% for control). Thinning fruit to leave 1 fruit per plant 1 week before harvest increased the proportion of fruit in a population that exceeded a quality control standard of 10% TSS from 20 to 80%. Variations in plant response with timing of treatment application are interpreted in terms of fruit development (cell division, cell expansion, and sugar accumulation phases). Although a detriment to yield (15 cf. 31 t/ha for control), the fruit thinning treatment was recommended for commercial use and a simple model was developed to calculate the required farm-gate price of fruit to make thinning economically viable.