8342937070

Pertanika 14(2). 119-124 (1991)

Growth and Physiological Changes of NFT-Grown Tomatoes (Lycopersicon esculentum) as Influenced by Salinity, Vapour Pressure Deficit (VPD)

and Root Temperaturę.

I. MOHD RAZI¹ andS.W. BURRAGE²

^ł Department of Agronomy and Horticulture Uniuersiti Pertanian Mataysia 43400 (JPMSerdang, SelangorDarulEhsan Malaysia.

² Wye College, Ashford,

Kent TN25 5AH, England.

Key words: Lycopersicon esculentum; salinity; vapour pressure deficit; root temperaturę; growth; water relation; photosynthesis.

ABSTRAK

Kesan kepekatan larutan nutrien, deficit tekanan wap dan suhu larutan ke ataspertumbuhan danprosesfisilogi bagi tanaman tomato (Lycopersicon esculentum Mili cv. Counter)yangditanam dałam sistem teknik aircetek (NFT) telah dikaji. Tanaman telah dibeń rawatan kepekatan larutan nutńen (2.5 mS/cm 8.5 mS/cm), deficit tekanan wap (0.16kPa; 0.80kl^}a) dan suhu larutan (12° C,22° C). Pertumbuhan daun dan akardikurangkan apabila tanaman ditanam pada kepekatan larutan tinggi, deficit tekanan wap rendah dan suhu larutan rendah. Pengurangan pertumbuhan daun oleh kepekatan tinggi dan suhu yang rendah adalah dihasilkan dań kesan tegasan airyang ditunjukkan denganpenguranganpotensi airdanpengambilan airoleh tanaman. Pengurangan kadar tranpirasi menghalangpergerakan nutńen tanaman yang ditanam dałam keadaan deficit tekanan wap rendah menyebabkan pengurangan pertumbuhan daun. Konduksi stomata mengurang bila tanaman ditanam pada kepekatan larutan tinggi, deficit tekanan wap tinggi dan suhu larutan yang rendah. Walau bagaimanapun, penguranga n oleh deficit tekanan wap tinggi dan suhu rendah tidak menjejaskan kadarfotosintesis bagi seunit luas daun.

ABSTRACT

The effects of salinity, uapour pressure deficit (VPD)and root temperaturę were inuestigated on the growth and physiologicalprocesses ofNFT-grown tomatoes (Lycopersicon esculentum Milicu Counter). Theplants wereexposed totwoleuels of salinity (2.5 mS/cm; 8.5 mS/cm)_t VPD (0. lókPa; 0.80 kPa) and root temperaturę (12 °C; 22°C). Leaf and root growth xoere reduced when plants weregroum at high salinity, Iow VPD and Iow root temperaturę. The reduction >n leaf growth at high salinity and Iow root temperaturę was attńbuted to the water stress effect indicated by a reduction in leaf water potential and plant water uptake. The reduction in transpiration ratę which limits the transfer of nutrient in the plants contńbutes to the reduction in leafgrowth at Iow VPD. Stomatal conductance was reduced when plants weregroum at high salinity, high VPD and lotu root temperaturę. This reduction at Iow VPD and Iow root temperaturę howeuer, did not affect the leaf photosynthesis ratę per unit leaf area.

rNTRODUCTION

Nutrient film technique (NFT) of growing plants is described as the mostsophisticated technologyyet conceived for improvement and control of crop production in thegreenhouse (Wittwer 1980).

In NFT-grown tomatoes, salinity and root temperaturę were manipulated to improve growth andfruitdevelopment. High salinity was reported ; ^l,)producedeleteriousaswell asbeneficial effects

on tomatoes (Costaef ai 1986; Adams 1987). High salinity inereased the osmotic potential of root en-vironment. As a result, water uptake is reduced, resulting in an internal water deficit in plants creat-ing an effect similar to that of plants exposed to drought conditions.

Plant growth and development were also inereased with inereasing root temperatures (Cooper 1973; Papadopuolos andTiensen 1987). This