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View the PDF document Yield advantage, competition effects and nutrient uptake in a common bean (Phaselous vulgaris)-Chinese cabbage (Brassica pekinensis) mixture in Samoa
Author:Nauluvula, Poasa.
Institution: University of the South Pacific.
Award: M.Sc.
Date: 2004.
Call No.: pac In Process
BRN: 1023702
Copyright:Under 10% of this thesis may be copied without the authors written permission

Abstract: The assessment of yield advantage, competition and nutrition uptake in a mixture of Chinese cabbage (Brassica pekinens;s) and common bean (Phaselous vulgaris) was conducted at USP School of Agriculture, Alafua Campus, Samoa, in a series of box and field experiments. The effects of forms of competition were studied in the box experiment where one variety each of Chinese cabbage and common bean were used. The same common bean variety Contender and two Chinese cabbage varieties Pakchoi Kwang moon and Pakchoi White were factorially combined with four organic sources of nutrients and grown in mixture and in pure stands to study yield advantage, competition, sources of nutrients and variety effects, under field conditions. The three organic sources of nutrients were poultry manure, bokashi and alroc with no source of nutrient added to soil as the control. The results from the field experiment confirmed the findings of the box experiment that common bean was more competitive at earlier stages and Chinese cabbage at later stages of growth. The mixture had eryield advantage over their respective mono-crops; it also gave yield advantage since both relative yield total (RYT) and land equivalent ratio (LER) were greater than unity. Common bean was slightly more competitive than Chinese cabbage, and the two components used different amounts of nutrients N, P and K, either in space or in time. The two crops could be grown successfully in mixture. From both experiments the LER of the mixture ranged from 1.00 to 1.71. Root competition had the highest LER at 1.71 in the box experiment and in the field experiment the highest LER of 1.66 was recorded in the mixture grown in poultry manure. This indicated that pure stands of both components require 71% and 66% more land respectively to produce the given amounts of yield of the components compared with, when grown in mixture, in the respective treatments. The RYT values in both experiments ranged from 1.49 to 1.81, which indicated that there was yield advantage from the mixture. RYT values of 1.0 or less than 1.0 would indicate that the two crops compete fully for resources and there was , no advantage of growing crops in mixture, an RYT of above 1.0 indicate that components partially competed for resources. The results indicated that the component crops did not fully compete with each other for limited resources. They only partially complemented with each other in the use of resources. From both the box and field experiments common bean was slightly more competitive than Chinese cabbage irrespectiv~ of the cabbage variety common ~/ bean was mixed with. In the box experiment common bean was more aggressive (aggressivity = 0.13) in full competition whereas in the field experiment, common bean was also most aggressive (aggressivity =0.14) in the mixture of common bean and cabbage variety Pakchoi White (PW) grown in the organic source of nutrients, "alroc". The nutrients N, p, and K uptake as determined from shoot analysis of both components in both experiments indicated that cabbage used more Nand K in both experiments. There were no significant differences in uptake within the individual crops but between them, significant differences occurred and indicated that the two crop components used different amounts of N, P, and K nutrients either in space or in time. The legume would use less soil N since it fixed its own N from the air. Results from both the experiments indicated that the mixture of Common bean and Chinese cabbage variety "Pakchoi Kwang moon" grown in poultry manure , could be a good cropping package for the Sa malaga village in the Alafua watershed. Furthermore the results from the field experiment confirmed the findings and results of the box experiment, which showed that the two crop could be grown together successfully in mixture.
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