Abstract
A field experiment was conducted at the experimental fields in the collage of Agricultural Engineering Sciences, University of Baghdad, Iraq during the period from mid. March 2019 to to end of July 2020. The main objective was to find out the effect of humic acid (HA) concentration (0, 1, 2 and 3 cm3.L-1) and three stages of foliar application (vegetative, growth, flowers buds emergence and 50% flowering) on seeds yield and its components of alfalfa local variety. Layout of the experiment was R.C.B.D arranged in split-plot, with three replications. Foliar application stages were used as main-plots, while humic acid concentrations were used as sub-plots. Results showed that spraying of HA at conc. 3 cm3.L-1 resulted in a significant increment in number of florets per raceme and number of pods per raceme, in contrast, % of florets abortion in and 1000 seeds weight were not significantly influenced by HA conc. and spraying stages. Highest number of the stems.m-2, number of racemes per stem, seed set and seeds yield (441.0) Kg.ha-1 were obtained from plants sprayed with HA at conc. 3 cm3.L-1. Plants sprayed at vegetative growth produce highest number of stems.m-2 number of raceme per stem, number of seeds per pod and seeds yield (423.6) Kg.ha-1. There was high positive correlation between seeds yield and each of, number of stems.m-2, number of pods per raceme and number of raceme per stem (+0.88**, +0.70** and +0.82**) respectively. There was a significant interaction between HA concentration and spraying stages on seeds yield. The higher seeds yield (485.) Kg.ha-1 was obtained when alfalfa plants were sprayed with HA at the conc. of 2 cm3.L-1 in vegetative growth.
Highlights
Alfalfa (Midicago satia) is one of the most perennial forage legumes in Iraq
The increases of alfalfa pasture throughout the world has increased the need for seeds. especially in Iraq, one of the major problems facing alfalfa cultivation for seed crop is the absence of the suitable guide lines for management during the critical period of seed crop
Utilization of organic fertilizer in agriculture has increased in recent years, after the efforts payed by researchers to replace the uses of organic substances instead of minerals fertilizers which became well known with their harmful effect on human health and environment pollution (Shehtm 2001)
Summary
Alfalfa (Midicago satia) is one of the most perennial forage legumes in Iraq. It is important in farming systems for at least two reasons, the first reason is their ability to restore fertility by fixation of atmospheric nitrogen, secondly, it has advantage over grasses and other legumes in terms of provide high quality forage for livestock [19]. There was no study conducted in Iraq on the effect of application of humic acid on seed yield and its components of alfalfa in order to increase the availability of alfalfa seeds to meet future fodder requirements. Three foliar application stages [ vegetative growth (two weeks after last cutting), flowers bud emergence and 50% flowering] were used as main plot, while four concentrations of humic acid (HA) (0, 1, 2 and 3 cm.L-1) were used as sub-plots. May 2020 and the crop left for seed set and following seed yield component were because this time lead the plants to reach flowering on the best time for insect's pollinators Table 2. 5- Seeds yield were estimated from middle lines, drying was made at the field and carried out according to the growth stages, threshing was made by hand. Fourty stems were chosen at random equation: Number of florets − number of pods
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