Response of Maize to Salicylic Acid and Mechanical Cultivation in reducing Some of Biotic and Abiotic Stresses and Their Effect on Growth Characteristics and Yield.

Abstract

A field experiment was carried out during the autumn season of 2016 in the fields of Field Crop Sciences, Baghdad University, in order to determine the effect of different concentrations of salicylic acid, mechanical cultivation and their interactions on weed control and reducing some of biotic and abiotic stress effects on growth characters and yield of maize (synthetic variety,5018). The experiment was carried out according to the randomized complete block design (RCBD) in split block arrangement in three replicates. The main plots included four mechanical cultivation [ control without cultivation), cultivation at 5 cm deep, 10 cm, and 10 cm with Triflane herbicide at [1L ha-1) 4 weeks after seeding]. While secondary plots included salicylic acid spraying with four concentrations (0, 50, 100, 200 mg L-1). The results showed that there was a significant effect of SA in reducing the biotic stresses of the weed and abiotic as the temperature rise. Salicylic acid spray increased the average vegetative growth characteristics of the plant. SA at 200 mg L -1 treatment gave the highest rate of plant height, stem diameter, leaf area, and dry weight of the vegetative system [186.16 cm. , 1.75 cm, (5965 cm2), (174.95 gm plant-1) respectively, while the control treatment gave the lowest rates in these characters (170.28cm), (1.49cm), (5018cm2), (162.37 g plant-1) respectively.. Salicylic acid treatment had no significant effect in the dry weight of the weed. Cultivation at 10 cm deep with triflan herbicides (W3) treatment recorded the highest rate of plant height, stem diameter, leaf area, which reached (191.59 cm), (1.75 cm), (5996 cm2), respectively, while the control gave the lowest rates in these characteristics, reaching (159.14 cm), (1.57 cm). Cultivation at 10 cm deep (W2) treatment showed a higher mean of dry weight (176.22 g plant-1), which did not differ to W3 (175.74 g plant-1), while (W0) treatment gave the lowest rate (158.18 g plant-1). (W2) showed the lowest dry weight of weed plants (223.7 g m-2), while the control treatment (W0) recorded the highest rate (842.7 g m-2). All of these effects have contributed to give high grain yield, for this (SA2) gave the highest rate of grain (7.37 ton ha-1), while SA0 gave the lowest rate (5.89 ton ha-1). (W2) showed a higher mean yield of grain ( 8.39 ton ha-1), while the control gave the lowest yield (3.64 ton ha-1). Here we can conclude that growth regulator (salicylic acid) has improved most of the growth characteristics and biological environment of the roots, which works to raise the plant viability in competition of weed plants and increase the efficiency of roots in the absorption and transfer the nutrients from the soil into the plant, thus increase the efficiency of photosynthesis and increase dry matter. It also showed a role of increasing most of vegetative growth and yield due encourage the plant to withstand the stresses which caused by the weed.