Abstract:

To rationally use irrigation techniques in the mid-early stage of tomato production in coastal saline alkali soil, spring tomato is taken as the research object to explore the effects of different soil matric potential (-10, -15, -20, -25 kPa) on the growth and photosynthetic indexes of tomato under drip irrigation. The results showed that: the number of irrigation decreased significantly with the decrease of soil matric potential at 0.2 m depth directly below the dripper, and the growth indexes of plant height, stem diameter and leaf length decreased gradually with the decrease of soil matric potential, and there was no significant difference between the treatment of -10 and -15 kPa. The biomass decreased gradually with the decrease of basal potential. The fresh weight of tomato plants with basal potential lower than -15 kPa decreased obviously, and there was no significant difference between -10 and -15 kPa. The net photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO₂ concentration decreased with the decrease of soil matric potential, there was no significant difference between the treatment of -10 and -15kPa, but the difference reached the significant level compared with the other two treatments. The total root length, total root volume and total root surface area decreased with the decrease of the basal potential. There was no significant difference between the two treatments (-10 and -15kPa), but the number of coarse roots >4 mm was the highest under the treatment of -15 kPa basal potential, the difference reached a significant level with all the other three treatments. The comprehensive analysis showed that in the mid-early growth stage of tomato in the coastal saline-alkali area, the irrigation should be controlling the lower limit of soil matric potential at -15 kPa at 0.2 m directly below the dripper.

Key words: saline-alkali land, soil matric potential, greenhouse tomato, growth indexes, photosynthetic indexes