What usually happens when you cut up a piece of fruit to eat or to put in a salad? If it is an apple, a pear, a peach or a plum, you probably cut out the seeds and put them in the compost bin. But it’s different with a kiwifruit. Most kiwifruit have about 1,000 tiny seeds, and they give the fruit an interesting, crunchy texture so we leave them in. Growers want their kiwifruit to have lots of seeds because it means the fruit will be bigger.
To get seeds in a kiwifruit, a female flower must be pollinated – the more pollen it gets, the more seeds it produces. Kiwifruit flowers are pollinated by insects, but the flowers are a bit unusual. The male and female reproductive parts are in separate flowers, which grow on separate plants. Insects need to collect pollen from male flowers and take it to female flowers. Fruit only grows from the female flowers, so growers put a few male plants amongst many female ones.
Kiwifruit growers often use artificial pollination to make sure their plants get all the pollination they need. People collect pollen by hand from male flowers and spread it onto female flowers. Scientists are trying to find the best way to do this, including when to pollinate kiwifruit flowers and how much pollen to use.
Dr Mark Goodwin and Dr Paul Martinson at Plant & Food Research are developing a machine called a RoboBee that can sense which flowers are female and spray pollen directly on to them. Normally, pollen is sprayed over the whole vine so a lot is wasted when it lands on leaves. Collecting and processing male pollen is very expensive, so the RoboBee will save a lot of pollen wastage.
Nature of science
The RoboBee is an item of technology that aims to mimic the natural process of kiwifruit pollination, which has become unreliable due to problems with honey bees. The science of pollination needs to be understood so that the RoboBee can carry out the same function in a different way.
In November 2010, the bacterium Pseudomonas syringae pv. Actinidiae (Psa) was discovered in a Te Puke kiwifruit orchard. Things looked grim for the kiwifruit industry. Find out how Plant & Food Research and industry partners fought the disease and returned New Zealand's kiwifruit production to full strength in the article Kiwifruit - learning to live with Psa. The article includes an interactive timeline of events, including links to the nature of science.