| || || Fa'amatuāinu, Walter|
| || || Dry matter accumulation and partitioning of two improved taro (Colocasia Esculenta (L.) Schott) cultivars under varying nitrogen fertilization rates in Samoa|
Institution: University of the South Pacific.
Subject: Taro -- Fertilizers -- Samoa, Taro -- Samoa -- Growth
Call No.: pac SB 211 .T2 F33 2016
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: The accumulation and partitioning of dry matter in two improved taro cultivars (Samoa 1 and Samoa 2) were determined to characterise their growth and development patterns. A split- split-plots experiment in a RCBD design with three replications was setup to determine the dry matter accumulation and partitioning of the two cultivars. Each replicate contain two main plots (cultivars) which were split to accommodate three nitrogen rates (0, 100, 200 kg ha-1). These were further split to accommodate five sampling (harvest) dates (35, 70, 105, 140, 175 DAP). During six months, all the data collected from the experiment were analysed using the GenStat statistical software. The two cultivars varied in dry matter accumulation to the leaf blades, petioles, roots, corms and suckers. Also, the dry matter partitioned to the different organs of the taro cultivars differed with respect to the rate of nitrogen used. The analysis of dry matter for the cultivars was carried out 35 days after planting (DAP) and continued until the final harvest six months after planting. During the early growth and development stages of the two cultivars, the leaves and petioles received greater portions of dry matter, however later on during the growth period, the corm and suckers dominated. Even though, the growth and development patterns of Samoa 1 and Samoa 2 were similar, the total dry matter of Samoa 2 was higher than Samoa 1. The two cultivars response to the amount of nitrogen applied was different depending on the taro part involved. The influence of the applied nitrogen was more profound in the aboveground biomass portions of taro plants during the early stages of growth which were clearly demonstrated in the pot experiment. In the field experiment it was observed that increasing the rate of nitrogen enhanced the leaf blades dry matter (LDM) and petioles dry matter (PDM) of Samoa 2 in contrast to Samoa 1. Furthermore, the differences between leaf blades, petioles, corm, roots suckers and total dry matter of Samoa 1 and Samoa 2 as result of the five sampling or harvest (DAP) were highly significant (P<0.001). Additionally, the leaf area index (LAI), plant height, number of leaves and suckers of Samoa 1 and Samoa 2 all increased early in the growth stages until 105 or 140 DAP before declining at 175 DAP. The difference in plant height, LAI, number of leaves vi and suckers were highly significant (P<0.001) between the two cultivars during the five harvest dates (DAP). The difference in plant height between the two cultivars were significant (P = 0.04) as result of the nitrogen added and the difference in LAI between the two cultivars was also significant (P = 0.003). The pot experiment which was carried out before the field experiment was vital in determining the responses of the different taro parts against the selected rates nitrogen (0, 50, 100, 150 and 200 kg ha-1). The statistical analysis showed that the application of nitrogen caused the LDM, PDM, CDM, RDM, SDM and TDM of Samoa 1 and Samoa 2 to be significantly different (P < 0.001) from each other. Moreover, the difference between the physiological characteristics of the two cultivars such as the LAI, height and number of leaves for the two cultivars were also statistically significant (P < 0.001) All in all, as revealed from both the pot and field experiments there were significant differences between the two cultivars (Samoa 1 and Samoa 2) in terms of their dry matter accumulations and partitioning as well as other physiological characteristics such as the LAI and plant height which in turn affected their growth and development.