Relationships between wheat yield, yield components and physico-chemical properties of soil under rain-fed conditions

Document Type : Research Paper


1 Irrigation Department, Shiraz University, Shiraz, I.R. of Iran

2 Irrigation Department, Shiraz University, Shiraz, I.R. of Iran.


This research was conducted to study and classify the physico-chemical
properties of soil, yield components of wheat and to determine the significance of
these parameters on the grain yield formation. In this research, seven statistical
methods consisting of simple correlation analysis (SCA), multiple linear regression
(MLR), stepwise regression (SR), factor analysis (FA), principal component
analysis (PCA), cluster analysis (CA) and path analysis (PA) have been
investigated. The physico-chemical properties of soil, different morphological traits
and wheat yield have been obtained from a field with 250×300 meter dimension
located in Bajgah (with silty clay loam soil) that consisted of 30 samples. Among
statistical analysis performed, MLR has provided more acceptable results. In this
method, among the examined characteristics, five traits i.e., the number of stems
without spikes per plant, biological yield, harvest index, soil soluble potassium and
soil available phosphorus, examined 98.3% of the variations of the yield (P<0.05).
Lack of soil nitrogen effect on yield is due to drought stress conditions in which the
plant growth is less sensitive to nitrogen. Furthermore, the negative effect of
phosphorus on the yield of plant may be due to the inverse relationship between the
soil phosphorus and micronutrient elements on the plant growth. Generally, among
the yield components, biological yield is the most important and effective trait on
grain yield, that has presented a significant contribution in different statistical
methods. For some of the used statistical methods, the measured traits, like length
of spike, the number of spikes per square meter, the number of grains per spike
and harvest index showed positive effects on the grain yield and other traits like

1000-grains weight, the weight of grain per spike and the number of tillers without
spikes per plant showed negative effects on the grain yield with the highest
correlation. Among different soil nutrition, soluble potassium, phosphorus, sulfate
and available potassium with positive effects and the clay content with negative
effects showed the most correlation with the grain yield.