عنوان مقاله [English]
Introduction: The advantages of plastic mulches have been known in production of agricultural crops. Their capability have been demonstrated to help nutrition uptake, precocity and yield of fruit trees, and decreasing of aphid population as viruses pest vectors. It is also demonstrated some advantages of plastic mulch on some traits in potato such as increasing growth rate, yield and number of medium tuber size. Also, the effects of combined use of straw, chopped and polyethylene as well as different levels of irrigation (60, 80, 100, 120% water requirement) on yield and water use efficiency in potato have been investigated. In previous studies, it is concentrated on the effect of the special type of plastic on growing aspect of potato and there is no comparative assessment between different types of the mulches. So that in this research we evaluated the responses between types of plastic mulches.
Material and Methods: this research was conducted under field conditions. A factorial experiment was designed based on randomized complete block design with three replications. The experimental treatments consisted of mulch in five levels (clear, white, black, double layer and control (without mulch)) and two cultivars (Agria and Sante). Each plot was designed in 4 m2. For every plot, ridges were divided into complicated double rows with 50 × 150 centimeters wide. Irrigation tapes were placed between every duplicated row. Water requirement was calculated through corrected evapotranspiration (ETo) by Penman-Monteith equation with considering 90% water use efficiency. During the growing season some characteristics such as requirement time to 80% emergence, tuberization time, plant height in flowering time, number of stems and leaf area have been measured. Harvesting time was recorded along with measurement of tuber weights. Total yield was measured by random selection of one m2 in each plot. Harvested tubers were separated based on three sizes; edible tuber (large tuber), average tuber and small tuber size. Tow-way analysis of variance (ANOVA) of data was carried out using SAS software and means were compared byDuncan’s Multiple Range Test at probability level of 5%
Results and Discussions: The results of the experiment showed that application of plastic mulch and cultivar had significant effect (P≤ 0.01) on most of growing traits. Effect of cultivar and plastic mulch had no significant different on tuber dry matter. Mean comparison of 80% emergence date, number of main stem, growth duration, ranking of tubers size and total yield showed significant effect between cultivars and plastic mulches. Sante cultivar with clear mulch reach in shortest time to 80% emergence (11.3 days) and tuberization time (46.46 days). Significant difference between polyethylene mulches in emergence date is due to the effect of mulch characteristics on soil temperature and moisture. Consequently, soil microclimate would be changed and growth habits of potato plant inclined to suitable responses. Clear plastic mulch had highest plant height and number of main stem compared to other mulches and control treatment. Leaf area also affected by mulches; so that four types of plastic mulches had more leaf area comparison to control. Significant effect of mulch treatments on leaf area can be related to conservation of moisture and reduction of water stress. Meanwhile, increasing of uptake and transferring of mineral nutrient can be promoted growth rate. All this reaction can increase leaf area in plastic mulch treatments. Totally, application of plastic mulches could improve growth rate, growth duration and total yield of potato.
Conclusions: The result of this research showed that polyethylene mulch can obviously increase growth rate as well reduce growth duration. Also, plastic mulch can significantly increase total yield and positive reaction effect on tuber size. Different types of plastic mulches showed different responses on growth traits and total yield. It seems clear mulch be more capable in the most traits and total yield compared with other plastic.