Soil fumigation, fruit production, and dry matter partitioning of field-grown strawberry plants

Bare-rooted 'Camarosa' strawberry runner plants were established in a fruit production field on 1 Nov, 1993 using annual hill culture and two preplant soil fumigation treatments: 1) a mixture of 2 methyl bromide : 1 chloropicrin (wt:wt, 392 kg . ha(-1)) injected into the soil before forming raised planting beds (MBC); or 2) nonfumigation (NF), At about 33-day intervals between mid-January and the end of May, 20 plants were destructively sampled from each treatment to determine leaf dry mass (LDM), crown dry mass (CDM), root dry mass (RDM), and shoot:root dry mass (SRDM) ratios, Plant mortality was <0.2% throughout the study and did not differ with soil treatment, Regardless of sampling date, LDM, CDM, and RDM were greater for MBC plants than for NF plants, although treatment differences were not always significant, During the first 143 days, NF plants allocated a greater proportion of dry matter to roots than to shoots compared to MBC plants, indicating that roots are a stronger sink for photoassimilate in nonfumigated than in fumigated soils. However, there was no difference between treatments in SRDM by the end of the study, Fruit yield and a 10-fruit weight were determined at weekly intervals from mid-January until 23 May 1994, Yield and mean fruit weight of NF plants were 72% and 90%, respectively, of that of MBC plants, For both treatments, about one-half of total fruit production occurred between 144 and 174 days after planting (late March to late April), During that same period, rates of dry matter accumulation in leaf, crown, and root tissues decreased for plants in both treatments, but greatest reductions occurred in NF plants, Chemical name used: trichloronitromethane (chloropicrin).