اثر سایه بان بر برخی ویژگی‌های کیفیت میوه به (.cydonia oblonga mill) رقم اصفهان در انبار

به منظور بررسی اثر سایه بان بر خصوصیات کیفیت میوه به رقم اصفهان در انبار، آزمایشی به صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی در سه تکرار در باغ به شرکت کشاورزی فجر واقع در شهرستان نطنز استان اصفهان در سال1400-1399 به اجرا درآمد. هزار متر مربع از باغ مجهز به سامانه سایه بان و بخشی دیگر بدون سایه بان بررسی شد. میوه ها 193 روز پس از تمام گل برداشت شدند و به سردخانه با دمای 1±0 درجه سانتی گراد و رطوبت نسبی 95 درصد منتقل شدند. در زمان برداشت و نیز پنج ماه پس از برداشت و نگهداری در انبار، ویژگی های کیفیت میوه ها مورد بررسی قرار گرفت. محتوای پکتین و فنل کل پس از دوره انبارمانی پس از پنج ماه تفاوت معنی داری را بین تیمارهای زیر سایه بان و بیرون سایه بان نشان نداد، اما میانگین میزان مواد جامد محلول کل (tss) (18/35درصد) و شاخص طعم (6/44) پس از پنج ماه انبارمانی در میوه های زیر سایه بان بیشتر بود. میزان کاهش وزن (6/41درصد) و قهوه ایی شدن (1/83درصد) در میوه های زیر سایه بان پس از انبارمانی کمتر بود. در بین عوامل و هوایی بررسی شده، شدت تابش در محیط زیر سایه بان (میانگین 11302/77لوکس) و بیرون سایه بان (میانگین 28881/10 لوکس) تفاوت مشهودی وجود داشت، به طوری که در بیرون سایه بان بیش از دو و نیم برابر زیر سایه بان بود. شاخص طعم بیشتر و نیز کاهش وزن و قهوه ایی شدن کمتر در انبارمانی میوه های تولید شده در زیر سایه بان از مزیت های کاربرد سایه بان در باغ های به است که کاربرد آن به باغداران پیشنهاد می شود.

effect of shading net on some fruit quality characteristics of quince (cydonia oblonga mill. cv. isfahan) in storage

in this research, the role of shading net on some fruit quality characteristics of quince cv. isfahan was investigated. the experiment was carried out on quince cv. isfahan grafted on the hawthorn rootstock in the quince orchard of fajr agricultural company located in natanz city in isfahan province, iran. trees were about 20 years old. fruits were harvested 193 days after flowering and were transferred to a cold store with temperature of 0±1°c and relative humidity of 95%. at the harvesting time and five months after harvest, the fruit quality characteristics were examined. the pectin content and total phenol content after five months of storage did not show significant difference between inside and outside of the shading net. however, the tss (18.35%) and the fruit taste index (6.44) swere higher in the fruits under the shading net after five months of storage. lower weight loss (6.41%) and browning (1.83%) were observed in the fruits under the shading net after five month storage. keywords: quince, weight loss, taste index, phenol, pectin, solar radiation. introductionchanging climate has become a major concern in the agricultural industry in the world. in the last 30 years, the temperature has increased by approximately 0.2 °c (hansen et al., 2006). environmental factors such as light quality and quantity, canopy and soil temperature, relative humidity and wind speed have been controlled by the shading nets. there are some reports on the effect of shading nets on tss and ta of fruits (meena et al., 2016). the shading net decreases tss in the fruit, because of reduction of light intensity, which plays an important role in the accumulation of tss in fruits. the reduction of ta under colored nets, especially dark shading nets compared to the control is due mainly to the reduction of photosynthetic active radiation and less accumulation of carbohydrates in the fruit (retamales et al., 2008). narjesi (2021) reported higher fruit taste index in pomegranate fruits of trees grown under cover compared to control trees. the main objective of this research was evaluation of effect of shading net and harvest time on some fruit quality characteristics of quince cv. isfahan in storage.. material and methodsthe experiment was carried out on quince cv. isfahan grafted on the hawthorn rootstock in the quince orchard of fajr agricultural company located in natanz city in isfahan province, iran. trees were about 20 years old. a plot with an area of one thousand square meters was equipped with green shading net system with with 50% shading. a plot was also kept without shading net as control. the experiment was layed out as factorial arrangements in randomized complete block design with three replications. to record weather parameters, two portable data logger were installed under and outside the shading net. fruits were harvested 193 days after full bloom. the fruits were transferred to a cold store with temperature of 0±1°c and relative humidity of 95%. at the harvest time and five months after harves, some quality characterstics such as fruit weight, length, diameter, firmness, total soluble solids (tss), pectin, total phenol, titratable acid (ta), taste index, browning, and weight loss percentage were measured and recorded. analysis of variance was performed based on principles of factorile experiment in randomized complete block design with three replications. means were compered using lsd test at the 5% probability level. results and discussionat the harvest time, the pectin and total phenol contents in the fruits were 1.72 times higher in fruits produced under shading net than in the fruits harvested outside shading net. storage duration led to the reduction of pectin and total phenol content in both conditions. after five months of storage, the difference in the pectin and total phenol content between the two conditions decreased and was not significant. the presence of a shading net on the trees, in addition to the delaying flowering time, also delayed the ripening of the fruits.storage duration increased the fruit tss content and taste index in quince cv. isfahan, however, this increase was greater in fruits grown under the shading net. at the harvest time, the tss content in fruits grown outside the shading net was 1.06 times more than in the fruits produced under the shading net. the fruits produced under the shading net showed lower weight loss and browning after five month in storage. water loss during the storage period leads to decrease in the fruit weight, and the decrease in the fruit weight has negative effect on the appearance and marketability of the fruits. the browning percentage in the fruits outside the shading net was 1.7 times more than the fruits under the shading cover.the monthly mean temperature and relative humidity was cooler and higher under the shading net. however, the monthly mean radiation intensity of the period under the shading net (11302.77 lux) was less than outside (28881.10 lux). using shading net in countries with high radiation intensity in mid-day leads to decreases in the radiation intensity, temperature of the leaf surface, stress of dehydration and heat in the trees, evaporation and transpiration, and prolongs the harvesting period. referenceshansen, j., sato, m., ruedy, r., lo, k., lea, d.w. and medina-elizade, m. 2006. global temperature change. proceedings of the national academy of sciences of the united states of america, 103, pp.14288-14293.  meena, v.s., kashyap, p., nangare, d.d. and singh, j. 2016. effect of colored shade nets on yield and quality of pomegranate (punica granatum) cv. mridula in semi-arid region of punjab. indian journal of agricultural sciences, 86, pp.500-505. doi: 10. 56093 /ijas. v86i4. 57485  narjesi, v. 2021. effects of different shade netting treatments on some quantitative and qualitative characteristics of pomegranate fruits cv. malas-e-saveh. journal of agricultural science and sustainable production, 31, pp.275-293. (in persian). doi: 10.22034/saps.2021.12815  retamales, j.b., montecino, j.m., lobos, g.a. and rojas, l.a. 2008. colored shading nets increase yields, profitability of highbush blueberries. acta horticulturae, 770, pp.193-197. doi:10.17660/actahortic.2008.770.22  paniagua1, c., pose, s., morris, v.j., kirby, a.r., quesada, m.a. and mercado, j.a. 2014. fruit softening and pectin disassembly: an overview of nanostructural pectin modifications assessed by atomic force microscopy. annals of botany, 114, pp.1375-1383. doi: 10. 1093/ aob/mcu149