Abstract
Genotype-envirenment interaction of some agrenomical characters
including yield of eight inbred lines and seme segregating generations
of rice (Oryza sativa L.) was studied. The inbred lines censisted of
three local and five exotic varieties such as Naizersail, Badshabhog,
Kataribhog, Chinese, IR-8, IR-532, IR-20 and IR-5 and F₂ generations
of five crosses made between tall and dwarf varieties were Chinese x
Kataribhog, IR-8 X Chinese, IR-20 X Kataribhog, Chinese X Naizersail
and IR-8 X Kataribhog.
The inbred lines under different eight were growm eight
nutritional treatments of presence and absence of N, P and K fertilizersin pots during 1977 for season I and during 1978 for season II. Each
experiment had three replications consisting two pots per variety and
per dose of nutritional treatment under each replication and they were
randomly arranged under direct sunlight. Five F₂ families and their
five parents were also grown in 1978 under the same eight nutritional
treatments having six replications for each treatment.
Due to the unavailability of data on yield and yield components
for the three local varieties during season II, the data were grouped
into the following four categories for analysis.
A. Yield and yield components of eight parental lines for
season I.
B. Yield and yield components and some morphological and
developmental characters of five parental lines for
seasons 1 and II. C. Morphological and developmental characters of eight
parental lines for seasons I and II.
D. Yield and yield components of five F₂s and their five
parents.
The data were collected on length of panicle, primary branches/
panicle, spikelet number/panicle, kernel number/panicle, 100 kernel
weight, yield/plant, tiller number, fresh shoot weight, dry shoot
weight, fresh roof weight, dry roof weight and plant height. The data
were then analysed following the techniques equivalent to those
developed by Yates and Cochran (1938), Mather and Jones (1958),
Finlay and Wilkinson (1963), Eberhart and Russell (1966), Bucio
Alanis (1966), Bucio Alanis and Hill (1966), Perkins and Jinks(1968a),
Bucio Alanis et. al. (1969) and Breese (1969).
Genotype-environment interactions were found to operate in
both parental lines and F₂ families. Greater portion of G X E interactioeffects was accounted by the linear function of the environmental mean,
although a significant part of the G X E effects was non-linear in
nature. Both the linear and non-linear components of 0 X E effects
were under the. control of different gene systens. A great genetic
diversity was observed in genotypes investigated.
As regards the effects of individual nutrition, N had the
largest single effect on most of the characters. N, P and NP
significantly increased the yield performances for all the varieties
and the F₂s. Amont the F₂8 IR-8 X Kataribhog gave the highest yield
performances. K had no effect on yield. High and low genotypic as well
as environmental variations were found in the characters investigated The genotypes had varied responses to different environments.
F₂ families were more responsive to the environments than those of
their parental lines. The standard error of the responses were
heterogenous indicating varied stability among the genotypes. 2
families differed from their parents with respect to the stability
within an environment but the stability values varied in different
characters and crosses. Association of mean (✗), responses (b) and
stability (2) was present in some characters and absent in others.
When they ( bi as well as ) were examined between characters,
they were found to be associated in some combinations while in other
combinations no association was noted.
Significant dominant and additive effects were indicated in
controlling the mean expression of these characters studied. Both
dominant and additive components of varistion interacted with the
environment but they were of different function of the environmental
means and were under different gene systems. Potence ratios were high
in poor environments and low in good environments in some characters
and in others the reverse was true.