The adj. massal selection (from the French sélection massale, as used in vine growing) appears to have replaced 'mass selection' (as found, for instance, in the 1990 edition of a hard copy of the Dizionario di agricoltura I owned) in recent years, and is currently the preferred term, as you can see in the excerpts below.

'The application of massal selection of superior phenotypes is recommended, among and within populations, aimed at establishing a clonal seed orchard for commercial seed supply.'
http://www.fao.org/docrep/006/ad317e/AD317E17.htm
(scroll down to the Seed Orchard paragraph in the second document)

'Vine diversity is preserved through Domaine Laroche’s massal selection. Massal selection is the visual selection and propagation of robust vines which are believed to have a diverse genetic base. Domaine Laroche benefits from exceptional plant diversity, as the viticultural team systematically selects and keeps the best vines to produce younger plants.'
http://www.wilsondaniels.com/our-portfolio/domaine-laroche/v...

'La sélection massale
Generally speaking, every winegrower’s ideal is a robust, resistant vine producing fine, healthy grapes with exceptional taste characteristics.
Massal selection aims to achieve that ideal by selecting and propagating only those vines producing the finest grapes.'
http://www.champagne.fr/en/from-vine-to-wine/grape-varieties...

'Selection Massale is the French term for selecting the best vines in a vineyard and propagating them through cuttings. Here Emmanuel Pageot of Domaine Turner-Pageot in Gabian in Languedoc explains the technique. Emmanuel is planting "own-rooted" vines without American rootstock.'
Here is the link to the video associated with the above description
https://www.youtube.com/watch?v=OMZPp0wpnl0

--------------------------------------------------
Note added at 2 hrs (2015-03-10 11:30:04 GMT)
--------------------------------------------------

Prego, Isabelle!

--------------------------------------------------
Note added at 5 days (2015-03-16 07:18:48 GMT) Post-grading
--------------------------------------------------

Thank you, Isabelle. Buon lunedì e buona settimana a te!