Studies of Flooding Tolerance, Irrigation Index and Water Management in Eustoma grandiflorum
Date Issued
2012
Date
2012
Author(s)
Tsai, Yu-Chia
Abstract
Abstract
Eustoma grandiflorum (Raf.) Shinns is one of the major flowers in Taiwan. Nowadays, the important issue is to enhance the quality of cut flowers by cultivation. Water is the important factor which affects plant growth. In this study we investigated the water status of Eustoma under water stress, and selected some flooding-tolerant cultivars and developed an irrigation index of Eustoma. In addition, compared the difference performance between Eustoma under drought and that under flooding.
Eustoma plants grown in 9 cm pot were treated with 10-day flooding followed by 2-day recovery. The results showed that the leaves of plant began to wilt from lower leaves, which also happened at upper leaves if the plant is a flooding-intolerant cultivar. Leaf water potential could instantly respond to the water status of plant, especially the relative water potential [(upper leaf water potential) / (lower leaf water potential)] may be an useful index to realize the water status of Eustoma under flooding. The results also showed that the damage of Eustoma under flooding was not significant, it probably because that Eustoma is a flooding-tolerant plant. After comprehensive assessment of eight cultivars, ‘Arena Ⅲ Champagne’, ‘Exrosa Lisa’ and ‘Rosina Ⅲ Pink’, which did not have significant variation after 10-day flooding, were flooding-tolerant cultivars; ‘Bridal Snow’, ‘Exrosa Green’ and ‘Jadegirl Blue Violet’ had slightly damage; whereas ‘Exrosa Blue Flash’ and ‘Pavane Green’, which had some of plants died after 10-day flooding, were flooding-intorlerant cultivars.
Eustoma ‘Rosina Purple’ grown in three media and stop water supply after fully irrigation. The results showed that the plants grown in clay loam soil grow better than those grown in 1-P or the mix (1-P: clay loam = 1: 1), because clay loam soil have better water-holding capacity which could help Eustoma to maintain adequate moisture. After rewatering of 11-day stopping water supply, the soil water content, Fv/Fm and leaf water potential of Eustoma had all recovered; but leaf chlorophyll meter reading (CMR), NPQ and dry weight of Eustoma had dropped. The water status of Eustoma was measured during stopping water supply period, and found that the temporary wilting range of leaf water potential in Eustoma was about -2.1 ~-2.8 MPa. The phenomenon of wilting firstly appears at lower leaf means that the lower leaf is water-sensitive and it is suitable to evaluate water deficit. Therefore, the irrigation index was recommend that when lower leaf water potential of Eustoma is about -1.6~ -2.1 MPa.
When compared the difference performance between Eustoma under drought and that under flooding. The results showed that ‘Pavane Green’ and ‘Exrosa Lisa’ had same phenomenon that the upper leaf water potential were more negative than the lower ones at the control. It indicated that water transport from bottom to top (transpiration) at normal conditions. Under drought condition, the lower leaf water potential is more negative than the upper one, which is also match the phenomenon that the lower leaves usually began to droop first when lacking water. There was no difference in 4 days flooding between two cultivars, but the lower leaf water potential was more negative than the upper one after 7 days flooding. The situation is similar to drought represented flooding could also makes the plant under physiological water deficit (root damage). The relative water potential could represent the plant water status. The value more than 1 expressed normal plant growth, whereas less than 1 may be under water stress during water deficit period. The relative water potential value of ‘Exrosa Lisa’ was more than 1, and ‘Pavane Green’ was less than 1. In conclusion, ‘Exrosa Lisa’ is more tolerant than ‘Pavane Green’ under water deficit. Both cultivars under flooding of their relative water potential was less than 1 after 7 days flooding, it showed that they were all under flooding stress.
Subjects
Eustoma
water potential
flooding
irrigation index
water management
SDGs
Type
thesis
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