Why some grapes are round while others oblong

Washington, Feb 18 (ANI): Although researchers are working towards developing elongated grape crops, classifying the shape of fruits comes as a big challenge for plant breeders. Thus, scientists have come up with a new method, SigmaScan, which can gauge fruit shapes just by analysing their pictures.

Before fruit arrives in local groceries, a lot of time and effort goes into creating the varieties found in the produce section.

Dr. John R. Clark is continuing the mid-1960's grape-breeding program to develop varieties with elongated shapes started by Dr. James N. Moore of the University of Arkansas.

And to make sure that the efforts are reaping results, it is required to characterize the shape variation and also work towards finding genetic markers that could help breeders produce elongated grapes without waiting years to see the actual fruit on the vine.

Visual observations can be highly subjective and ratings often variable among observers.

One of the digital methods for analysing shapes has been used for tomatoes, but it requires each fruit to be cut in half and scanned to take the measurements, making the fruit unusable for additional studies or for eating.

But the digital analysis method, called SigmaScan, which is in use at the University of Arkansas' turfgrass science program, selects colours within a given range of a photograph to analyse turf quality mechanically, eliminating human error.

The technology was borrowed by the university's fruit breeding program for a study of grape shapes led by Clark and graduate student Andrew P. Wycislo.

The study began with digital photos of grapes developed specifically for the project. The seedlings exhibited wide variation of shape-from round to very elongated.

Using a special application of the SigmaScan technology that measures the area of the grape by differentiating it from the background colour, calculations were made about the shape of each grape. They also rated every grape manually based on elongation.

"Visual inspection supported the SigmaScan analysis," said the researchers.

The grapes used for the study were frozen at the time of harvest and did not need to be thawed or cut for being photographed.

At one time, researchers photographed ten grapes, but they said that more grapes could be shot and studied in a single photo in the future to further the speed of study.

Thus, it was observed that SigmaScan improves efficiency, and because the fruit is still intact, it can also be used for additional studies or consumption.

The method has potential for future breeders by helping them to select grapes based on degree of elongation, and can also be applied to studies of other fruits.

Although none of the elongated grapes have been released for public use as yet, it is hoped that in the future these new and unique grapes will be an addition to the expanding fresh fruit profile for American consumers.

The study is published in the American Society for Horticultural Science journal HortScience. (ANI)