International Journal of Noni Research - Noni Family

57 Intl. J. Noni Res. 2007, 2(1-2)
D.R. Singh et al. Morinda citrifolia L. – An evergreen plant for diversification in commercial horticulture
Salinity tolerance
Noni is a highly salt tolerant tree that thrives in wet and dry conditions. There
is a membrane enclosing a gel like substance around each seed enabling
flotation, and the seed coating, being very hard and watertight, can delay
sprouting for many months. The flower is self pollinating; so only one seed needs
to sprout for a successful population to possibly emerge, these are positive traits
for sea or air dispersion and colonization in any harsh conditions, from salt flats
to lava flows. Influence of seawater inundation on vegetative growth of Morinda
sp. after one year of planting indicates that the plants reached maximum height
of 88.80 cm with 6-8 branches with first bud initiation 62 days after planting and
fruit setting on 75 days after planting. An average yield of 1.10 kg fruits per plant
was obtained. The soil pH was recorded to be varying from 6.18 to 8.28, EC from
0.18 to 14.25 and the pH of water was recorded to be varying from 6.98 to 8.32
and that of EC from 0.26 to 21.28.
Irrigation with 75% sea water revealed luxuriant growth of Morinda citrifolia
L. in respect of plant height (72.0 cm), stem girth (0.7 cm), number of leaves
(52), in which EC was 13.26 dsm –1 and pH of 7.31 followed by 100 percent
sea water which recorded plant height (70.0 cm), stem girth (0.7 cm), no. of
leaves (49) and the EC was 17.79 dsm –1 and pH of 7.63 whereas in control
(normal water irrigation) the plants reached a height of 51.5 cm, stem girth of
0.5 cm and number of leaves was 51.5 in which the EC was 2.5 dsm – 1 and
pH of 7.67. First bud initiation was recorded in 100% sea water within 361 days
from the date of planting followed by 366 days in 75% sea water and in control
was observed on 410 th days after planting.
Gas exchange parameters
Measurement of gas exchange parameters revealed that photosynthetic active
radiation (1459 µmol/sq m /s), photosynthesis rate (27.8 µmol/sq m/s), stomatal
conductance (75.54 µmol/mol), transpiration rate (2.48 million mol/sq m/s) and
internal Co2 (654.04 k Pa) were recorded from plants growing under
wasteland and plants growing under sea inundated and recorded photosynthetic
active radiation (731.6 µmol/sq m/s), photosynthesis rate (26.70 µmol/sq m/s),
transpiration rate (0.70 µmol/sq m/s), and internal CO2 (769.80 kPa).
In sodium chloride (Nacl) irrigation experiment, the results revealed that
rate of photosynthesis was maximum (7.90 µmol/sq m/s) in plants irrigated
with 19.25 g Nacl/4 litre water whereas PAR was high (115.90 µmol/sq
m/s) in plants irrigated with 26.25 Nacl / 4 litre water, rate of transpiration,
stomatal conductance and internal CO 2 were recorded to be high (1.30
µmol/sq m /s, 79.80 µmol/mol and 771.80 kPa ) in plants irrigated with
normal water (control).