IMPACT OF Conocarpus erectus L. FERTILIZER, AND SOME MICRONUTRIENTS ON GROWTH AND PRODUCTION OF POTATO

This study was aimed to determine the impact of Conocarpus erectus L. compost fertilizer, and some micronutrients on growth and production of potato. This research was conducted at one of the fields of the College of Agricultural Engineering Sciences University of Baghdad. The experiment was implemented using factorial arrangement (4X3X3) within randomized complete block design with three replicates. Conocarpus fertilizer was represented the first factor with three levels (7.5, 15, 30 ton.ha -1 ), which symbolized (C2, C3, C4). Chemical fertilizer as recommended dose as a control, which symbolized (C1). The second factor was foliar spraying with three levels of iron (0, 100, 200 mg.L -1 ), which symbolized (F0, F1, F2). The third factor is foliar spraying with three levels of boron (0, 50, 100 mg.L -1 ), which symbolized (B0, B1, B2). The statistical analysis showed superiority of C3 in producing significant values of the studied traits such as, leaf area (154.77, 187.93 dcm 2 ) for fall and spring seasons respectively, plant yield (649.7 gm.) for fall season only. Also the results revealed the significant impact of F2 treatment in producing high leaf area (153.63, 177.22 dcm 2 ) for fall and spring seasons respectively. B2 treatment demonstrated significant values in producing high starch percentage (10.09%, 10.85%) for fall and spring seasons respectively, The results that obtained from triple interaction exhibited significant superiority of treatments C1F1B2 and C3F2B0 in producing the highest plant yield (811 g, 1239.2 g.) for both seasons respectively.


‫العراقية‬ ‫الزراعية‬ ‫العلوم‬ ‫مجلة‬
Potato plant (Solanum tuberosum L.) belongs to Solanaceae family considered one of the most crucial vegetable crops in worldwide. It comes after cereals in daily human consumption. Potato classified as a starchy veggies that has a large amount of starch and decent amounts of vitamins C, A, and B in addition to minerals such as potassium and phosphorus (8). Recycling pruning wastes of Conocarpus trees that planted abundantly by composting process have dual advantages. First, getting rid of their heavy biomass that affects the environment in a large scale if it gets burned. Second, having a high quality compost that serves as a fertilizer (13), and carbon sequencer (12). As a result, there are many studies focused on Conocarpus compost in Middle East region. Alkoaik et al (3) noticed significant increasing in emergence index for radish seeds when planted in composted Conocarpus media. Usman et al (22) mentioned that adding Conocarpus bioachar (8% w/w) to soil mitigated salt stress on tomato plant. Moreover, it was caused increasing in yield (43.3%) in comparing to control treatment. The physiologists revealed the major role of micronutrient in plants especially iron and boron. Iron has multifunction in plants, but the most essential one is that it is the main component in heme proteins and Fe-S proteins. The mentioned proteins play a vital role in photosynthesis and respiration. In addition, iron is crucial to preserve the structure and function of chloroplast (21). Boron has a significant task in nucleic acids metabolism and DNA synthesis (6). Moreover, it facilitates the efflux of inorganic ions across root tissues (21). Many researches emphasized the importance of foliar application for supplying potato plants of its needs from minerals and nutrients (17,19). Moinuddin et al (15) reported that spraying potato plant with a fertilizer content iron and boron increased the plant height, number of leaves, and root length. Manjunath et al (14) showed that foliar spraying with fertilizer had both of iron and boron with organic manure increased dry matter and total sugar content. As what mentioned previously this study aimed to manufacture a high quality fertilizer from pruning residues of Conocarpus plant after composition and experiment it for the first time on the growth and yield of potato plant. In addition to study the effect of iron and boron and their interaction with Conocarpus fertilizer on the growth and yield of potato plant.

MATERIALS AND METHODS
This research was conducted at research station (A) College of Agricultural Engineering Sciences, University of Baghdad (Al-Jadiryah). Table 1 shows the chemical and physical properties of the soil for the two seasons. The field divided in to beds with 1.5 m length and 1 m width (the plot area 1.5m 2 ). Each plot has 12 plants with 0.25 m in between. The field was under drip irrigation system. The tubers of potato var. Arizona (from Al-Awrad agricultural company) were planted during spring and fall seasons in 11/9/2018 and 18/1/2019 respectively. The experiment was implemented factorial arrangement (4X3X3) within randomized complete block design with three replicates. Conocarpus fertilizer was represented the first factor with three levels added to the soil within planting (7.5, 15, 30 ton.ha -1 ) which symbolized (C2, C3, C4). In addition to chemical fertilizer as recommended dose (240N, 120P, 400K kg.ha -1 ) (2) as a control, which symbolized (C1). Table 2 shows the chemical and physical properties of Conocarpus fertilizer which was prepared according to Al-Zaidy (4). The second factor is foliar spraying with three levels of iron (0, 100, 200 mg.L -1 ) (FeSO 4 20% Fe as a source of iron) which symbolized (F0, F1, F2). The third factor is foliar spraying with three levels of boron (0, 50, 100 mg.L -1 ) (H 3 BO 3 17% B as a source of boron) which symbolized (B0, B1, B2). The first spraying was after 45 days from planting (Active vegetative growth stage).The second spraying was after 15 days from the first spraying (Tubers initiation stage). The third spraying was after 15 days from the second spraying (Tubers enlargement stage). The characters studied were, plant height (cm), leaf area, plant -1 (dcm 2 .plant -1 ),total tubers.plant -1 , plant yield (kg.plant -1 ), and starch percentage in tubers% (1). Harvesting from all the plots occurred during spring and fall seasons in 18/1/2019 and 5/5/2019 respectively. The collected data analyzed using analyses of variance and the means were compared according to L.S.D. test under 5% probability (9). The analysis was carried out in in the Laboratories of Agricultural Researches Center, Ministry of Agriculture. Table 3 show

3-Number of tubers.plant -1
The results in Table 5

4-plant yield (g. plant -1 )
The results in Table  6 show superiority of of Conocarpus compost on plant yield. The treatments C3 and C1 produced significantly highest plant yield (649.7 g. plant -1 ) (1053 g. plant -1 ) for fall and spring seasons respectively, while the lowest potato plant yield found from the plants of the treatments C2 (459.17 g. plant -1 ) (798.4 g. plant -1 ) respectively. Table 6 also shows the impact of iron feeding on plant yield. The highest plant yield was found from treatment F1 (673.23 g. plant -1 ) (972.9 g. plant -1 ) for fall and spring seasons respectively in comparison with the lowest plant yield from the plants of F0 (470.83 g. plant -1 ) (899.5 g. plant -1 ) respectively. B1 and B2 show the highest plant yield (605.9 g. plant -1 ) (950 g. plant -1 ) ( Table  6) for fall and spring seasons respectively. While, B0 demonstrates the lowest plant yield (532.7 g. plant -1 ) (909 g. plant -1 ) for both seasons respectively. Second order interaction had the highest significant treatments C3F1 and C1F1 (749.4 g. plant -1 ) (1111.5 g. plant -1 ) for fall and spring seasons respectively. The lowest plant yield found from treatment C2F0 (349.4 g. plant -1 ) 708.3 g. plant -1 ) for both seasons respectively. The results for the interaction for treatment C1B2 had a significant increase in plant yield (710.6 g. plant -1 ) (1119.9 g. plant -1 ) for fall and spring seasons respectively. In comparison with the lowest plant yield that found from the plants of the treatment C2BO (435.9 g. plant -1 ) (776.4 g. plant -1 ) for both seasons respectively (Table  6).

5-Starch percentage of potato tuber
The results of potato tubers starch % (Table 7) show the impact of Conocarpus compost on tuber starch percentage %. Significant differences were found between C4 and C1 (10.13%) (11.10%) for fall and spring seasons respectively, while the lowest values found in C2 (9.47%) (9.32%) respectively. Table 7 shows the effect of iron foliar spraying on tuber starch. The highest percentage were from F1 plants (10.08%) (11.41%) for fall and spring seasons respectively in comparison with the lowest percent in F0 (9.74%) (9.52%) respectively. B2 treatment shows significant superiority on starch percentage (10.09%) (10.85%) for fall and spring seasons respectively. However, B0 shows the lowest percent (9.59%) (9.63%) for both seasons respectively. The interaction results in  It could be observed from these results the strong and fast impact of chemical fertilizer. In fact, it's fast solubility and availability to the plant led to these findings in comparison with the organic fertilizer (18). The significant results that came from foliar feeding with iron are due to its crucial role as a part of hemic proteins and Fe-S proteins, which have vital role in photosynthesis, respiration. Furthermore, iron is a component of the electrons transport enzymes (Redox reactions) such as cytochromes (20,21). These findings are in harmony with Awad et al (5) and Estaji et al (10). The significant superiority of foliar application with boron might be resulted from its effect on growth of meristematic tissues, building of nucleic acids, and sugars translocation. Furthermore, boron increases the absorption of potassium (6). These results in agreement with Awad et al (5). The positive findings of Conocarpus fertilizer could be interpreted by improving the mentioned fertilizer the physical and chemical properties of the soil (Table 2), such as increasing its water retention, creating ideal atmosphere for root growth, increasing the activity and numbers of microorganisms, and increasing the availability of the minerals and that reflects on the strength of vegetative growth and increasing the photosynthesis products and accumulates in tubers (7,13), this is consistent with the results of Kang (11) and Moyin-Jesu (16).