Effect of Organic Manure, tuber weight and ascorbic acid spraying on some tubers chemical components of potato ( Solanum tuberosum L.) grown in sandy soil

Field experiment was conducted in AL-Najaf Governorate during the season of 2011 in two cultivations (spring and autumn) . The aim was to study the effect of different conc. of organic manure, different weights of tuber seeds and Ascorbic acid spraying on tuber content of N, P, K, total soluble solid and ascorbic acid on potato plant (Solanum tuberosum L.) cv. Proventa. The experiment included 24 treatments, i.e. the interactions of four levels of organic manure (0, 75,100 and 125 kg/furrow), three tuber weights at cultivation (big, medium and small) and two concentrations of ascorbic acid (0 and 150 mg/l., sprays were done twice during the season with 15 days interval, that was done on 45 days from cultivations. Factorial conducted with Randomized Complete Block Design (R. C. B. D.) was used with three replications. Means were statistically compared according to Duncan's Multiple Range test at probability of 0.05. Results indicated that the use of different levels of organic manure had significant effect on most of chemical parameters N, P, K, total soluble solids and amount of vitamin C content in tubers. 125 kg/furrow gave the highest means for the measured parameters for both cultivations compared with control treatment which gave the least values for these parameters. On the other hand, tuber size treatment had a significant effect on the most of chemical parameters that surpassed plants produced from big size tuber compared to that plant produced from small and medium tubers. Ascorbic acid spraying had significant effects on most of chemical parameters compared with plants with out spraying of ascorbic acid. The interactions among the three factors were showed presence of significant effects on the most of chemical studied parameters for both seasons. Introduction Potato, Solanum tuberosum L. , is the most important agronomic tuber crop in the world. Today, potato is grown in more than 130 countries and over a billion people worldwide eat it, making it the third most important food crop in the world after rice and wheat. It is a major source of inexpensive energy. Potato produces more food per unit of water than any other major crops. and also an excellent source of complex carbohydrates. No other crop can match potato in its production of food energy and food value per unit area (Nevain et al., 2007). The United Nations FAO reports that the world production of potatoes in 2009 was 330 million tones. The use of compost in Agriculture in most countries of the world is gradually increasing as a result of the promising results achieved through their experiences with its management. Compost application to the soil has several beneficial effects on crop yield and soil fertility by improving and increasing soil organic matter, water holding capacity, nutrient contents, Print ISSN: 2073-8854 & Online ISSN: 2311-6544 Magazin of Al-Kufa University for Biology / VOL.6/ NO.2/ Year : 2014 http://www.kufabiojournal. org http://www.uokufa.edu.iq/journals/index.php/ajb/index / http://iasj.net/iasj? func=issues&jId=129&uiLanguage=en E.mail: biomgzn.sci@uokufa.edu.iq 2 soil aggregation, and microbial activity (Griffin and Porter, 2004; Elisabetta and Nicola, 2009). Also, compost application has positive effects on the crop yield, root system and stimulation of plant-growth due to hormones (García-gil et al., 2000). Generally, potato is cultivated through tuber planting and eyes number influences potato yield (Siddique et al., 1987). The coast of seed tuber is very high and occupies about 40% of total production cost (Farooque et al., 1984). For this reason the large seed tubers are usually to consumer and small tubers which used to cultivate and thus minimizing the seed cost. Proper vegetative growth is needed for potato cultivation because more tubers are obtained from the plants of more vegetative growth and development. Ascorbic acid (vit. c) functions as antioxidant, as enzyme factor and as growth regulating factor. It plays an important role in different processes, including photosynthesis, photoprotection, cell wall growth and cell expansion resistance to environmental stresses of synthesis of ethylene, gibberellins, anthocyanins and hydroxyproline (Nicholas and Wheeler, 2000). The aims of this study are: 1Studying the production of potato crop according to organic agriculture technique by using different amounts of organic manure to protect human health and environment from the harmful effects of chemical fertilizers. 2Cultivation of potato in the desert soils and irrigated with salty wells water to assess the tolerance of potato plant growth. 3Using ascorbic acid as antioxidant to increase the tolerance of plant stress and increasing the productivity. 4Codification in using the tuber through using small, medium and large tubers due to the cost of using large tubers at cultivation. Materials and Methods An experiment was conducted during the growing season of 2011/2012 in the spring and autumn cultivations. Seeds (tubers) were sown on 30/1/2011for spring cultivation and on20/9/2011 for autumn cultivations that harvested on 21/5/2011 for spring and on19/1/2012for autumn cultivations. Both cultivations were grown at desert region between Najaf and Kerbla provinces. "Proventa tubers cv". was chosen which introduced by Ard company which imported from the Netherlands, which divided into three sizes according to their weights and volumes (Big, Medium and Small) i. e. 115.1 g. ; 52.2 mm.3 and g. 62.5; 45 mm3 and g. 30.96 ; 34 mm3 respectively, according to average weight and size of ten tubers for weight and size,. then, the experimental spot was divided in to 12 furrows at the length 20 m. the distance between each furrows one meter. Each furrow was divided of three parts with length of 6.6 m. and then each part was divided of 3.3 m. length. Tubers of the three sizes were cultivated at 40 cm. apart on both sides of the furrow. The experiment design was Split-split design with ( R.C.B.D.) Randomized Complete Block Design with three factors 1: Organic manure at three levels (75, 100 and125 kg/furrow) besides, control treatment 2: Tuber size (Big, Medium and Small). 3: Ascorbic Acid (Antioxidant) spraying on vegetative part. With two levels: 150mg/l and without spraying (control treatment). Cultural practices were done equally and when it is considered necessary irrigation, cultivation, weeding, etc. as mentioned in (Matlob et al, 1978). Irrigation was done from well water with E.C. 5.3 ds.m -1 by dripping system. Duncan's Multiple Range Test was used to compare means when treatment effect was evident, considered significant at probability of 0.05( Al-Rawi and Khalaf-Allah ,2000). Print ISSN: 2073-8854 & Online ISSN: 2311-6544 Magazin of Al-Kufa University for Biology / VOL.6/ NO.2/ Year : 2014 http://www.kufabiojournal. org http://www.uokufa.edu.iq/journals/index.php/ajb/index / http://iasj.net/iasj? func=issues&jId=129&uiLanguage=en E.mail: biomgzn.sci@uokufa.edu.iq 3 Table (1): Chemical and Physical characters for field soil before and after experiment Characters Before Expt. After Expt. Unit pH 7.2 7.0 -Ec 1.0 1.5 ds.m -1