Nutrition

Science programme: Optimising fruit & crop growth

Hortresearch is actively involved in work on the impact of plant nutrition on fruit quality, storage and storage disorders.

We have an analytical chemistry laboratory which has the equipment to measure the major inorganic nutrients including calcium, potassium, magnesium and phosphorous. Linda Boyd is project manager and she works on several projects for industry partners, other researchers and PhD students.

For further information on nutrition of particular crops go to http://www.hortnet.co.nz/publications/guides/fertmanual/fertind.htm.

We regularly field enquiries from industries concerned about their nutrient inputs and are often involved in field trials. These include trialling new products and comparing different methods of enhancing nutrient uptake. Dr Ian Ferguson, HortResearch's chief scientist, is a NZ representative on the International Plant Nutrition Colloquium. Nutrition may not always be the focus of the research but a nutrient imbalance can have marked effects on productivity and fruit storage so it is always a factor worth considering in explaining problems of storage and fruit quality.

Guidelines have been established for Integrated Fruit Production for apple growers, and for kiwifruit growers in the KiwiGreen programme.  Under contract we continue to look at new ways to increase the efficiency and effectiveness of fertiliser inputs for horticulture.  Some of this work is undertaken on organic orchard blocks in Te Puke (kiwifruit) and Central Otago (apples) where we are particularly interested in how to maintain production and fruit quality under organic or ‘Biogro’ standards  http://www.biogro.co.nz.

Gene maps for ‘bitter–pit’ susceptibility

The level of calcium in the fruit can strongly influence fruit storage for apples, and as part of a genetic mapping project we are studying the influence of calcium on the inheritance of bitter-pit susceptibility in apples.  This research aims to identify key genes which control the susceptibility of apples to bitter-pit and other storage disorders.

Many of the key genes involved in the physiological response to nutrient stress in apples and kiwifruit have been identified in the HortResearch genomics EST database, and with the gene technology group we are studying some of the genes that regulate nutrient uptake. Plant nutrition is relatively easy to study in small contained systems, and the discovery of genes controlling nutrient uptake could potentially lead to the use of less fertiliser, as plants are made more efficient in utilising natural sources of nutrient.

Nutrient balance and fruit quality

Many fruit are stored for a long time before reaching the consumer, and kiwifruit can be stored for several months. The storage quality of many types of fruit is related to balance of nutrients within the fruit. Chilling injury in avocados, and the development of  physiological disorders in kiwifruit and apples are some of the problems which we are studying.

Our work includes conducting large-scale surveys to identify the relationships between nutritional status and storage quality, and whether we can predict which fruit are more suited to long-term storage. We are also involved in determining which orchard management practices, including pruning systems, and fertiliser and spray applications, are most beneficial to fruit quality.