1,721,070 research outputs found
Developmental changes in xylem functionality in kiwifruit fruit: implications for fruit calcium accumulation
No full textIn kiwifruit, as in most fruits, storage quality is related to calcium concentration and many disorders are associated with low fruit calcium status. Previous studies show that after an early rise, fruit calcium concentration decreases because calcium influx ceases by the mid-growth stage whereas volume growth continues till harvest. Calcium transport to the fruit is exclusively via the xylem - calcium is not phloem mobile. We postulate that declining fruit xylem functionality is responsible for this pattern of calcium accumulation. Xylem functionality was measured from fruit setting to harvest in 'Zespri Gold(TM)' kiwifruit. The applied measurement technique consists in "transpiring" an apoplast-mobile dye into detached fruit through the stalk and recording the percentage of dyed (functional) bundles in sections cut along the length of the fruit. For the middle part of the fruit analysed, the dye method revealed high bundle functionality till about d10 (after bloom). A drastic reduction in the number of functional bundles occurred around d20 and, again, around d55 and d90. Some recovery was observed between these time steps. An almost complete permanent dysfunction was evident nearly at d120 up to harvest time. Fluctuations in bundle functionality are interpreted as being due to vessel breakage (resulting from stretching caused by fruit expansion) and temporary functional recovery resulting from early season differentiation of new vessels. The length growth rate is very high in the first 8 weeks from full bloom with a maximum value of 1.3 mm d(-1) at the 4(th) week. In this period, the fruit achieves 70% of the total length at harvest time. We conclude that patterns of xylem dysfunction in Zespri Gold(TM) provide a satisfactory explanation of the well-known patterns of fruit calcium accumulation
Variazione della conducibilità del sistema xilematico del frutto di actinidia durante il ciclo di crescita
No full text
Water and carbon economy in sustainable orchards in Mediterranean environments
No full textAgriculture is a key socio-economic sector and a driving force of sustainable development as it is involved in conservation of natural resources and in climate changes because it contributes to greenhouse gases (GHG) by sources as well as removals, through photosynthesis. To face increasing global population and food security agriculture should improve the water productivity. Improvement of orchard management practices aimed at increase soil fertility traits (e.g., soil organic carbon, microbial community, porosity) will be beneficial also for improvement of water use efficiency at farm scale through improved soil water holding capacity. This paper examines some effects of sustainable orchard management (Smng) practices (no-tillage, pruning residues and cover crop retention, compost application) in a Mediterranean environment, organic carbon and irrigation volumes. Comparisons were made against the conventional management (Cmng). Orchards under Smng increased the amount of carbon removed from atmosphere and stored as biomass and organic carbon into soil. Adoption of cover crops at the Smng orchard might remove 1.5-3.6 t C ha-1 year-1. Through a life-cycle assessment (LCA) approach, this paper reports that application of Smng practices is able to reduce by ∼20% the GHG emissions throughout the whole lifespan of orchards compared to Cmng. Adoption of the Smng practice was also beneficial for the reduction of the amount of irrigation water supplied which was approximately 20% lower than that of Cmng. Implications on the economic water productivity are also reported
Calcium accumulation in fruit of kiwifruit grown under different windspeed conditions
No full textMany physiological disorders of fruit are associated with low fruit calcium status. This is true for kiwifruit in which fruit storage quality is closely related to fruit calcium concentration. It is well known that calcium transport to a fruit is exclusively via the xylem - calcium is not phloem mobile. Therefore, a fruit's calcium status will depend on the cumulative inflow of xylem sap through the stalk; this will depend on fruit transpiration, and on the microenvironment in which the fruit develops. A plausible hypothesis says that if the windspeed around a developing fruit is increased, fruit transpiration will be increased, and likewise the accumulation of fruit calcium. To test this hypothesis, trials were conducted, on 10-year-old kiwifruit vines (Actinidia deliciosa 'Hayward') growing in Palmerston North, New Zealand. At fruit set, 12 small electric fans were mounted in the canopy to modify the wind environment of the immediately adjacent fruit. The fans were in operation continuously (24 h /day for several months) from fruit set through to harvest and the wind speed experienced by individual tagged fruit was measured periodically using a small vane anemometer. At harvest the calcium contents of ventilated and control fruits were analysed. The results show that increased windiness is associated with marked increases in fruit calcium
Effects of different irradiance levels on some antioxidant enzymes and on malondialdehyde content during rewatering in olive tree.
No full text- …
