Effect of paclobutrazol concentration and application methods on the spikelet number per spike, one of the main components of yield, in the apex development of spring wheat
In many countries, including Iran, wheat (Triticum aestivum L.) is a valuable crop. In the meantime, the application of plant growth regulators is proposed as a valuable strategy, especially in modern agricultural practices. The objective of the present study was the effect of priming and foliar application of Paclobutrazol (plant growth regulator) at different concentration of it on the length of initial spike and the final number of spikelet’s, in The Apex development, for study of increasing wheat production and higher yield per unit area This experiment was carried out as factorial in a Randomized Complete Block Design with 16 treatment and three replications in the research farm of Department of Agriculture, Maragheh University, in 2013-2014 years. The first factor included priming at 4 levels (Control, hydro-priming, priming with 25 and 100 mg. lit-1 PBZ); and the second factor included foliar application at 4 levels (distilled water (Control), 30, 60 and 90 mg. lit-1 PBZ). In this experiment, spike sprouts of main stem were cut to measure the length initial spike and the number of initial spikelet’s (using a calibrated microscope), The other characteristics of spike number per m2, spikelet number per spike per m2, grain number per spike per m2, 100-seed weightper m2, seed yield per m2, were measured. The obtained data were subjected to a statistical analysis using SPSS, MSTAT.C; Statistical Analysis System. The analysis of variance showed that seed priming had significant (p≤0.01) effects on number of spikelets per spike per m2, grain number per spike per m2, and was (p ≤ 0.05) significant on the spike length per m2, 100-seed weight and grain yield per m2. The means of the collected data from the different treatments during both PBZ applications were compared using Duncan’s test, with P≤ 0.05 and P≤ 0.01 as significant. As compared to other priming’s, priming the seeds with 25 mg.lit-1 PBZ. increased the length of initial spike and the final number of spikelet’s; however by increasing the concentration of PBZ solution, the length of initial spike and the final number of spikelet’s were decreased. In fact, priming the seeds with 25 mg.lit-1 PBZ solution. prolonged the period of spikelet growth during apex's vegetative stage of spring wheat which finally led to an increase in the number of spikelet’s per spike.
Key words: Apex, Foliar application, Paclobutrazol, Priming, Wheat.