Effects of water stress and potassium fertilisation on growth, development and fruit flavour of tomato (Lycopersicon esculentnm Mill.)

Abstract

The effects of water stress and potassium fertilisation on growth, development and fruit flavour of tomato (Lycopersicon esculentum Kill.) were examined. A series of experiments were carried out in the United Kingdom (Wye) and Greece (Patras) during 1984, 1985 and 1986 in pots , the field and in door protection. The effects of water stress on tomato were examined during both the propagation and post planting stages under favourable light conditions (spring plantings). Duringthe propagation stage two (1984) or three (1985) watering regimes were established to induce different degrees of water stress, namely "wet", "moderate " and " dry". Leaf Relative Water Content (RWC) was used as an indicator of internal water stress . Water stress applied after the initiation of the first in florescence did not induce flower abortion or alter the flowering capacity of the transplants. In contrast, there was evidence that abundant water supply enhanced flower development and resulted in larger transplants which produced early fruit yield. In the border soil, two water regimes were tested, namely "wet" and "dry". In the wet treatment less than 35% of AWC, while in the dry one, more than 90% AWC was depleted before irrigating the soil. Thecorresponding soil water tensions were above 0.1 3 MPa and below 1 .4 MPa for the wet and dry treatment respectively. The drought imposed on the plants significantly reduced vegetative growth and also total fruit yield due to are duction in fruitsize. Total soluble solids, titratable acidity and fruit dry matter were significantly increased. The amounts of potassium fertiliser applied up to 1550 kg ha ^ ^ no^ affect plant growth, fruit yield or titratable acidity. Soil and leaf analyses were carried out. The possible causes of the lack of response to potassium are discussed. There was evidence that Nitrogen increased titratable acidity. High fruit yield was produced in outdoor staked culture (123.5 tha " 1 ) and under protection (131.6 tha’ 1 ) for 30 - 40 days in Patras. Requirements for asuccessful out door crop under British conditions are discussed. The cherry type c v . S-100 was more vigorous and matured earlier than the beef steak cv . Dombito and was also superior in flavour.