Tenuta literally means to retain or maintain. In the context, it probably means to retain the fruit as long as possible on the plant.

In this connection, I have found tenuta di maturazione in pianta, and it could be that the fruit is then retained on the plant in order to ripe properly, therefore, this would be ripening on the plant or that the ripe fruit is retained for as long as possible on the plant.

The slow yellow change with meridians that remain very obvious and the excellent retention of ripe fruit on the plant, combined with a high sugar content and unique aroma, make Bernini F1 an ideal solution to reduce labor costs, providing very high and distinctive quality standards

https://zw.tomahnousfarm.org/12790-in-italy-introduced-a-new...

Strawberry fruit ripened rapidly on the plant, going from first blush of color to full red in about 1.5 days.

During ripening on the plant, met hyl esters increased 3 to 5 times while ethyl esters remained unchanged.

https://www.actahort.org/books/464/464_98.htm

The massive and intense amount of illumination provided by the present invention facilitates a high degree of efficiency in the picking of the strawberries. The pickers have a large field of view and enough time to be able to determine which berries are ready to be picked and which berries need further ripening on the plant.

https://www.freepatentsonline.com/y2010/0050588.html

Ottima la tenuta in pianta, si consiglia di attendere la maturazione completa per ottenere i dati sui frutti sopra riportati.

https://www.dalmontevivai.com/prodotto/dalmored-one/

Tra le caratteristiche più interessanti delle nuove varietà ci sono: elevato quantitativo in zuccheri della polpa, elevata pezzatura dei frutti, autofertilità della pianta, rapida messa a frutto, maggiore capacità produttività in termini quantitativi, maggiore tenuta in pianta dei frutti maturi, elevata resistenza al cracking.

http://www.italiafruit.net/DettaglioNews/29300/in-evidenza/v...

Questo conferma i rilievi di pieno campo e di magazzino dove si sono distinte per l’elevata tenuta di maturazione in pianta e nei processi post-raccolta.

https://coltureprotette.edagricole.it/archivio/innovazione-v...