The effect of rootstock on yield and quality in processing tomatoes

As the amount of arable land on earth is reduced over time, it is imperative to create technologies that permit higher yields per unit area. The practice of grafting cultivars with good fruit characteristics onto rootstock with greater vigor, or resistance to poor soil conditions is a common practice in many crops. The objective of this study is to evaluate the effect of different rootstocks on yield, quality, and phenological aspects of the leading tomato cultivars used in the Argentine market. Trials were conducted in La Consulta, INTA Experimental Station in Mendoza, Argentina during the seasons 2016-17 and 2017-18. Drip irrigation was used and daily water replenishment was done by a single surface tape according to evapotranspiration tank type “A”, adjusted by local Kc. During the two seasons different rootstocks by Japanese top-grafting method in Proplanta nursery were compared using common cultivars as scions. In season 2016-17, Magnitude (Rijk Zwaan) rootstock with 'HM 7883' (H.Moran) and 'Fokker' (Bayer) as scions were studied. In the season 2017-18, Superpro (Vilmorin) as rootstock with 'HM 1892' (H. Moran) as scion was studied in a plant density trial. Different rootstocks with 'HM 1892' as scion were tried to find rootstock influence in productivity performance. All parameters were evaluated by ANOVA using Duncan's test at α=0.05. The results obtained in the field showed significant increments on grafted plants, 29, 44.2 and 34.9%, respectively in marketable yield in different trials compared to non-grafted plants. In general, the use of suitable rootstocks lengthened the growing season about 5-7 days, compared to non-grafted plants. Significant 9% Brix reduction was found in 2017-18 trials but no differences were detected in season 2016-17. Different rootstock trials showed that total and marketable production was increased using Protector (H. Moran) and Superpro as rootstocks compared to the non-grafted treatments. Vine healthiness was improved in most of the rootstocks and significantly more vine covering was detected after 40 days of planting. Overripe, pH, blossom end index and culls were not affected by grafting. Density trials indicated that more than 18,000 plants ha(-1) probably will not be needed using grafted plants with appropriate rootstocks.