This experiment was carried out to breed promising brown anther type male sterile lines of carrots having the desirable characteristics of higher seed yield and stable phenotypic expression of male sterility. Brown anther type male sterile lines used for this experiment had been derived from the male sterile sources selected from the seed multiplication plots of Shin Kurota cultivar in 1972. Brown anther type male sterile lines are, in general, good seed yielders but frequently show unstable phenotypic expression of male sterility as compared to petaloid type male sterile lines. Through several years of selection for male sterile lines and plants, brown anther type male sterile lines with good seed-yielding potentials and stable phenotypic expression similar to petaloid type were developed. Outline of the breeding scheme, potential benefits of these newly bred MS lines, etc. will be discussed.
Jae-Young Lee*, Yong-Koo Kim, and Hee-Seung Park
To maintain appropriate tree shapes for Asian pear trees, multi-leader system would be more suitable, which could be obtained from the proper training systems. Controlling apical dominance should be the major factor for tree shape management and this might be modified by branch bending or pruning methods. When the tree shape was managed with Alternate Fan System, too narrower branch angle depressed flower bud formation because of the vigorous shoot growth but too wider angle also decreased that formation because of the numerous water sprouts. The tree with 75 degrees of internally deviated angle performed superior result in fruiting process. Additionally, heading-back pruning could be another for water sprout emerging. For that reason, the severer heading-back pruning stimulated the more water sprout emerging. The proper pruning method could be obtained by considering the relation between main stem width and sum of remained branch width.
Myong-Dong Cho, Yong-Koo Kim, and Hee-Seung Park
`Yumyeong' peach has the desirable characteristics of long shelf-life and specific non-melting nature with a long harvest period. However, some fruits harvested too late show fruit pithiness symptoms or internal breakdown. This study was conducted to analyze the differences between fruit flesh pithiness and internal breakdown symptoms and to find out the source of flesh pithiness in `Yumyeong' peach. The rate of flesh pithiness was higher in fruit harvested late in the season. Sugar and malic acid contents showed no differences between the normal and flesh pithiness fruits, but the acidity was significantly lower and was affected by low citric acid content in flesh pithiness fruit. In flesh pithiness fruits, calcium contents were low both in skin and flesh. Occurrence of flesh pithiness fruits was high in the years with low precipitation and high temperature for 2 months before harvest. In observations on morphological characteristics, the parts showing flesh pithiness consisted of smaller cells than the normal parts. Tonoplasts disintegrated and the number of dead cells was high in internal breakdown fruits, while the tonoplasts were intact, with contracted vacuoles, in flesh pithiness fruits. Tylosises were observed in vascular tissues around the flesh pithiness; therefore, it was assumed that those tylosises restrict flesh tissue development, resulting in flesh pithiness. Other varieties (`Fantasia', `Wolmi' and `Hakuto') also showed tylosis, and smaller cells were observed in the flesh tissue of these cultivars, indicating abnormal growth of the flesh part. These results suggest the possibility of the occurrence of pithiness-like symptoms in other peach varieties.
Myong-Dong Cho, Hee-Seung Park, and Yong-Koo Kim
`Yumyeong' is one of the most popular peach varieties in Korea. This study was conducted to monitor the developments of cells and tissues, and the changes in sugar contents during the whole fruit growth stages. At bloom, there were two rows of vascular tissues, and the number and the position of internal vascular bundles were consistent during the fruit growth; however, the number of vascular tissues increased and the distribution was irregular in the flesh tissues. The tissues between the inner integument and the internal vascular bundles showed different development characteristics from other parenchyma cells, which consisted of small and dense cells containing tannins. Therefore, it was found that the nucleus of peach consisted of inner epidermis and cells in the internal vascular tissues. The outer epidermis consisted of single layer cells at bloom and was changed into one to two layers by horizontal cell division 14 days after full bloom. At 30 days after full bloom, the epidermis consisted of five to six layers by vertical cell division. The cell layers of the outer epidermis gradually decreased to one to two layers at maturity. The observations on the changes in the epidermis confirmed that some of the cells of the hypodermis of peach fruit originated from the cells of outer epidermis. Tylosis was observed from 35 days after full bloom, and the size and number of tylosis increased until full fruit maturity. The sucrose content sharply increased from 50 days to 120 days after full bloom, then decreased slightly. After stone hardening ended, other solids showed a gradual decrease from 80 days after full bloom.
Youngsuk Lee, Hun Joong Kweon, Moo-Yong Park, and Dongyong Lee
Nutrient content assessment of plant tissues is widely performed by farmers to determine the appropriate amount of fertilization to use for their crops. A nondestructive leaf chlorophyll meter is one of the most commonly used devices for performing field assessments of the nutrient status of leaves. However, it is challenging to use a chlorophyll meter to assess the nutritional status of perennial plants, such as the apple (Malus ×domestica) tree, because of the difficulty estimating nitrogen (N) during the entire growing period. We compared the chlorophyll meter readings with leaf nutrient profiles collected from young ‘Arisoo’/M.9 apple trees throughout the growing period. A significant positive correlation between the chlorophyll meter readings and leaf N content was found from May to August during the midseason. Regression analysis indicated that the best sampling time for predicting the foliar N content of apple tress is from late June to late July. This result suggests that a reliable leaf N assessment can be performed in a rapid, nondestructive way in apple orchards.
Young Soon Kwon, Soon-Il Kwon, Jeong-Hee Kim, Moo Yong Park, Jong Taek Park, and Jinwook Lee
Yong Seo Park, Clara Pelayo, Betty Hess-Pierce, and Adel A. Kader
`Shinko' and `Shinsui' Asian pears were kept in air, 2 kPa O2, 2 kPa O2 + 2.5 kPa CO2, and 2 kPa O2 + 5 kPa CO2 (balance N2 in each treatment) at 0 °C or 5 °C for up to 24 weeks. The three CA treatments reduced respiration (O2 consumption) and ethylene production rates relative to air control pears; these rates were higher at 5 °C than at 0 °C and higher for `Shinsui' than for `Shinko' pears. While `Shinsui' pears had a climacteric pattern of respiration and ethylene production rates, `Shinko' pears produced very small quantities of ethylene and exhibited a non-climacteric respiratory pattern. `Shinko' pears had a much longer postharvest life than `Shinsui' pears (24 weeks vs. 12 weeks at 0 °C). CA treatments had a greater effect on delaying deterioration of `Shinsui' than `Shinko' pears, which were more sensitive to CO2 injury and associated accumulation of fermentative metabolites (acetaldehyde, ethanol, ethyl acetate). `Shinko' pears did not benefit from CA storage and were best kept in air at 0 °C. An atmosphere of 2 kPa O2 with or without up to 5 kPa CO2 delayed flesh breakdown of `Shinsui' pears during storage 0 °C.
Eun Young Yang*, Keum Soon Park, Dong Soo Lee, and Yong-Beom Lee
This study was conducted to understand the effect of different nutrient control method on the growth, cut-flower quality, root activity and fertilizer consumption. Single-node cutting rose `Versillia' was grown in aeroponics and DFT system and was irrigated with the nutrient solution of the Univ. of Seoul (NO3 -N 8.8, NH4 -N 0.67, P 2.0, K 4.8, Ca 4.0, Mg 2.0 me·L-1). Recirculated nutrient solution was managed by five different control method: macro- and micro-element control in aeroponic system (M&M); macroelement control in aeroponic system (M); nutrient solution supplement in aeroponic system (S); electrical conductivity (EC) control in aeroponic system (EC-A); EC control in deep flow technique system (EC-D). The mineral nutrient control method had significantly effected on the cut-flower quality. In the M&M and M, flower length, fresh weight and root activity were higher than those with other mineral nutrients control method. Although EC-A and EC-D could save total amount of fertilizer compared to M&M and M, the growth and quality of the rose with EC control system were lower than those with mineral nutrient control system. Therefore, these result suggest that EC control system is not economic method in a closed hydroponic system.