Chilling-Requirement Release of Seed and Bud Dormancy in Apricot

Dormancy shows common physiological features in buds and seeds. Specific period of chilling is usually required to release dormancy. Reproductive meristems and embryos display dormancy mechanisms in specialized structures named respectively buds and seeds that arrest the growth of perennial plants until environmental conditions are optimal for survival. Chilling requirements for breaking dormancy were studied for 3 successive years in 20 seedling apricot trees which spanned the range of flowering times in these trees. Different methods for estimating chilling requirements were evaluated and compared, and correlations between chilling requirements and flowering date were established. The trees examined showed a range of chilling requirements, chill hours (CH) between 199 CH and 274 CH, and chill units, (CU), between 612CU and 873CU. The results obtained in different years by the Utah and Dynamic models were more homogeneous with respect to the hours below 7 °C model. The apricot trees showed important differences concerning flowering date, and the results indicate a high positive correlation between chilling requirements and flowering date.Moreover, a specific low-temperature stratification treatment was required to overcome seed dormancy. 5°C cold stratification was found to be the best for breaking seed dormancy and germination. Increased seed germination percentage was recorded when the period of stratification prolonged. Apricot seeds required a cold stratification of about 12-15 days to reach maximum germination.

Mengembangkan skenario panen porang satu musim melalui manipulasi tanam lebih awal dan perlambatan waktu dorman fase generatif dengan pemberian asam salisilat organik alami di lahan kering Lombok Utara

The research on the scenario of one-season porang harvest through crop manipulation and delaying dormancy time aims to determine the effect of salicylic acid in breaking the dormancy of porang bulbil seeds during seeding and to determine the effect of slowing down the dormant period of the generative phase, so it is expected to be an alternative porang cultivation technology that is profitable for farmers The method used in this study used a completely randomized design experiment on breaking dormancy and a randomized block design in an experiment with slowing down the dormancy time of the generative phase with four salicylic acid concentrations (0%, 0.5%, 1%, and 2%) with eight replicates were planted under rainfed conditions. The results showed that the concentration of salicylic acid (C7H6O3) 2% was the best treatment in increasing tuber weight (52.25%) compared to the control. Application of Salicylic Acid (2%) was significantly able to increase the vegetative growth of porang plants, which was shown by increasing plant height by 50.38% and breaking seed dormancy 14 days faster than the control (without the addition of Salicylic Acid). Furthermore, the delay in dormancy time occurred 1 month later than the control so that it could prolong the vegetative phase. The concentration of 2% salicylic acid is the best treatment, which can be recommended in the development of one-season porang cultivation technology that can increase farmers' profits.

The Effect of Sodium Hypochlorite (NaOCl) and Heat Treatments on Seed Germination of Rice: An Approach to Restore Seed Viability

Dormancy in rice serves as a mechanism of survival by protecting the seed from germinating in the mother plants; however, it becomes a problem in germination during sowing in soil or under in vitro conditions. This study was conducted to determine the effect of heat treatment and sodium hypochlorite (NaOCl) treatment of seeds on dormancy alleviation. The seeds included both freshly harvested seeds and one-year-old stored seeds, which were tested for germination after different types of seed treatments. Both the treatments increased the germination percentage in seeds, however, it was lesser in the case of old seeds. The best results were obtained from 2% NaOCl treatment for 24 hrs in new seeds, i.e. 92.84±0.103 % germination percentage (GP). However, the higher GP in old seeds were obtained from 48 hrs of heat-treated seeds i.e. 82.9±0.509 % GP. The results of the experiment revealed that rice seeds start to lose viability within a year due to seed dormancy, but this can be reversed with proper measures. These methods of breaking seed dormancy can be considered effective to break seed dormancy and improve seed germination in rice.

Clone x Tester Crosses on Compatibility Level of Sweetpotato (Ipomoea batatas L.)

Evaluation of compatibility on sweetpotato is very important to determine the crossing parents to increase the compatibility of controlled cross-pollination. This research was aimed to study the level of compatibility in controlled cross-pollination based on percentage of normal seedlings obtained from crosses. The research was conducted at Kendalpayak Experimental Station of ILETRI, Malang, Indonesia then followed by breaking seed dormancy and germination of seeds obtained. The genetic materials used were 17 accessions with high yielding potential and 3 accessions as tester for crossing. The results showed that there were differences in the compatibility levels of crossing combination and their compatibilities as male or female parents. Clone C-011 (Tester 2) was the most compatible as male parent, while clone C-141, C-007 and C-131 were the most compatible as female parents. Clone C-127 (Tester 3) was the most compatible as both male and female parents. Clone C-001 (Tester 1) could not be used as female parent due to high incompatibility.This compatible clone information is very useful in determining of both controlled crosses and open crosses in sweet potato in order to increase the breeding efficiency.

SEED GERMINATION OF GUNDELIA TOURNEFORTII L. UNDER DIFFERENT DORMANCY BREAKING TREATMENTS

Gundelia tournefortii L. is adapted to mountains area climate, and the germination of this plant is not easily. This research conducted to study the effect of different seed treatments in various treatment durations in two experiments in petri dish in the laboratory and in seedling tray in the lath house to breaking seed dormancy and germination stimulus. Results indicated that there is significant enhancement of germination by all treatments and the maximum germination percentage was obtained by seed freezing 99.17% in the laboratory and 93.33% in the lath house for all treatment durations 12, 14, 48 and 72 hours. The other parameters of seed germination like germination speed, peak value, mean daily germination, mean germination time, germination value, radicle length, radicle elongation velocity, plumule length, plumule elongation velocity, seedling fresh and dry weight escalated by seed freezing and seed soaking in tap water at all soaking durations 12, 24, 48 and 72 hours. Gundelia tournefortii L. germinated seed was an anatomically examined by paraffin method and calculated diploid number of chromosomes 2n=2x=18 by aceto-carmine squash methods

THE CONTROL OF APRICOT SEED DORMANCY AND GERMINATION BY LOW TEMPERATURE TREATMENTS

Objective: Freshly harvested seeds of “Local” apricot variety were found to be dormant and did not germinate at all. A specific low-temperature stratification treatment was required to overcome seed dormancy. The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C cold stratification (CS). Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds. Methods: For stratification treatments, the seeds with removed endocarp were mixed with moistened sand. Afterward, they were subjected to a period of stratification at 5°C. Seeds were stratified in pots of 30 cm×40 cm. Stratified seeds were regularly irrigated once per week. To prevent the water loss during stratification upper surface of pots was covered by a sack. The following stratification was applied for apricot variety: CS for 0, 3, 6, 9, 12, and15 days in 1998 and 1999 years for “Local” variety. Results: Apricot seeds required a CS of about 15 days for “Local” variety to reach maximum germination and normal seedling growth. Moreover, when stratification period was prolonged, some of the chemical constituents of apricot seeds were increased and other was decreased. Therefore, it can be suggested that breaking of dormancy is coincided with several changes in different chemical constituents of seeds. Some of these materials increased (total, reducing and non-reducing sugars, total free amino acids, total indoles, and total and conjugated phenols) and other materials such as free phenols which decreased at seed germinations. Conclusion: The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C CS. Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds.

Influence of different methods for breaking seed dormancy of Ambrosia artemisiifolia, Abutilon theophrasti and Xanthium strumarium on emergence in field conditions

Seed dormancy is an important trait that contributes to the survival rate of weeds, helps to avoid the effects of herbicides and protects them against adverse environmental conditions. In order to determine which methods are effective in breaking seed dormancy of invasive weed species (Ambrosia artemisiifolia, Abutilon theophrasti, Xanthium strumarium), an experiment was set up in 2019 in a randomized block design, with three replications in the experimental field of the Institute of Field and Vegetable Crops (Novi Sad). The collected seeds of one population of A. artemisiifolia and A. theophrasti, were cleaned and stored in cold storage at 4°C until testing, while X. strumarium was stored at room temperature. Seed propagation was done in a weed science laboratory, using nine different methods for breaking seed dormancy. The seeds were exposed to different conditions of temperature, light and humidity over a certain period of time (24h or 48h). The dynamics of weed emergence were monitored daily, for a period of 31 days and expressed cumulatively in percentages. Based on the obtained results, the highest percentage of sprouted plants was determined in treatments where the seeds were propagated under light conditions, in water. An appropriate method of propagation can influence the breaking of seed dormancy and emergence in field conditions, which can have practical significance in the research of competitive relations between crops and tested weed species.

Mutu Fisik Dan Teknik Pematahan Dormansi Benih Kayu Kuku (Pericopsis mooniana (Thw.) Thw.)

The presence of Pericopsis mooniana (Thw.) Thw. in nature is endangered. Meanwhile, Pericopsis mooniana plants have its obstacles in generative propagation because the seeds have mechanical dormancy. Studies carried out to: (1) observe the morphology of pods, seeds and sprouts of Pericopsis mooniana; (2) determine the physical quality of Pericopsis mooniana seeds, and (3) analyze the proper dormancy breaking treatment for Pericopsis mooniana seeds. Research is conducted in laboratories and in greenhouses. The physical quality of the seeds measured was the weight of 1,000 seeds and the moisture content. The treatment for breaking the dormancy of the Pericopsis mooniana seeds were control, scarification of the seeds using nail clippers and soaking in hot to cold water for 48 hours. Morphologically, the fruit of Pericopsis mooniana is pod-shaped, with orange seeds, oval-shaped and curved edges. Pericopsis mooniana sprouts include in the epigeal type. In 1 kg of weight there are ± 4,000 Pericopsis mooniana seeds, with the post harvest seed moisture content amounting to 7.62%. The dormancy breaking treatment of Pericopsis mooniana seeds increased seeds germination by 60% compared to controls. The scarification of Pericopsis mooniana seeds using nail clippers for breaking mechanical dormancy is the best treatment because it can increase the number of seeds germinating in a short time and simultaneously. Key words: breaking seed dormancy, morphology, Pericopsis mooniana, physical quality, seed scarificatio