Effect of nursery regimes and establishment irrigation on root development of Lotus creticus seedlings following transplanting

Summary

The influence of irrigation and temperature regimes in the nursery on the dynamics of root development after being transplanted with minimum management conditions was investigated in Lotus creticus. In the nursery period (three months), plants were pot-grown in greenhouses, heated and unheated, located on the Southeast Mediterranean coast of Spain. Drip irrigation was used, with three irrigation treatments: T-6, plants watered 6.d a week at the water-holding capacity; T-3, plants watered 3.d a week; and T-2, plants watered twice a week. The total water applied over the whole nursery period was (in litres per plant): T-6, 7; T-3, 3.5; and T-2, 2.3. After the nursery period, plants were transplanted in a growth chamber into transparent containers (round acrylic tubes 8.cm diameter and 100.cm tall) and just one establishment irrigation was applied. Three treatments were applied, using three different amounts of water in the establishment irrigation: 10, 30 and 60.mm. The containers were kept in the growth chamber for one month, until the end of experiment. The harsher the conditions after transplanting (less water in the establishment irrigation) the more evident was the positive effect of hardening in the nursery. The regime involving least water and lowest temperature in the nursery period produced plants best adapted to stress at transplanting: a greater root length:shoot length ratio, higher percentage of brown roots and lower fresh weight:length ratio in shoots. All the plants survived transplanting. The most stressed plants in the nursery (least water and no heating) showed greater and more rapid root growth than the less stressed plants, especially when soil moisture was low.