THE INFLUENCE OF MECHANICAL ROOT PRUNING ON DRY MATTER PARTITIONING AND STAND ESTABLISHMENT RATE OF TOMATO (LYCOPERSICON ESCULENTUM MILL.) SEEDLINGS UNDER SALINE CONDITIONS

Graded seeds of an indeterminate tomato cultivar were sown in individual plugs filled with peat compost. The total number of seedlings was split in five equal groups. Twenty-five days after sowing (DAS), 1/3 of root system for the first group (rps 1/3-25 DAS) and 2/3 for second group (2/3-32 DAS) was removed and the plants were replanted to similar trays with the same plug size. One week later (32 DAS), the same procedures were applied respectively to the third (rps 1/3-32 DAS) and fourth group (rps 2/3-32 DAS). Rests of the plants (nps) were continuously grown in their initial plugs. Forty days after sowing, randomly selected plants of each group were transplanted into individual 150 cm3 plastic pots filled with peat substrate. Each of groups was subdivided in three equal subgroups, and periodically irrigated with equal amounts of either tap water, or saline water (50 mM and 100 mM NaCl). Several times, during nursery period and after transplanting, 10 plants per each experimental plot were randomly harvested and to each of them leaf area were measured, and roots, stems and leaf dry matter were weighted. Growth rate during the nursery stage and stand establishment rate after transplanting, defined as the root relative growths rate (RRGR), as well as root-shoot allometry coefficient (RSA), were computed for each experimental plot. Root pruning has significantly affected dry matter partitioning in young plants by primarily addressing the majority of assimilates to the reformation of new lateral roots. The most significant differences between intact and pruned seedlings were found regarding the root relative growth rate (RRGR) after transplanting. The root dry mass of pruned seedlings was increased much faster than their above ground mass. Root pruning has improved plant photosynthetic efficiency (NAR). Due to that, root pruned seedlings holds improved abilities ensures them a higher relative growth rate/stand establishment rate especially under saline conditions.