Pomology
S.A. Mousavi; M. Tatari
Abstract
Introduction
Peach×almond (GN) hybrid rootstocks have favorable characteristics such as ease of rooting, favorable growth vigour, resistance to nematodes, calcareous and dry soil (Babadaei et al., 2018). Currently, water deficiency caused by reduced rainfall is a major concern and a critical limitation ...
Read More
Introduction
Peach×almond (GN) hybrid rootstocks have favorable characteristics such as ease of rooting, favorable growth vigour, resistance to nematodes, calcareous and dry soil (Babadaei et al., 2018). Currently, water deficiency caused by reduced rainfall is a major concern and a critical limitation for agricultural production (Hass et al., 2021). Under drought stress, plant cell membranes become more susceptible to electrolyte leakage. Membrane leakage is caused by uncontrolled free radicals and leads to lipid peroxidation (Cheng et al., 2018). Since tolerance to drought stress is the result of the interaction of morphological and physiological traits of plant, therefore, a combination of different traits that have a direct relationship with drought tolerance can be used as selection criteria to screen the ideal cultivar (Karimi et al., 2015).
Materials and Methods
This research carried out during the years 2020 and 2021 at the Chahartakhteh station affiliated to the Center for Research and Education of Agriculture and Natural Resources in Chaharmahal and Bakhtiari Province. The almond seedlings included Shahroud 6, 7, 8, 10, 12, 13 and 21, that all of them grafted on the GN rootstock, along with GN rootstock, subjected to different drought stress treatments in June for four months. Drought stress treatments included 70% of field capacity (control or no drought stress), 50% field capacity (mild stress), 30% field capacity (moderate stress) and 10% field capacity (severe stress). A counter determined the amount of irrigation in each treatment, and a Time-Domain Reflectometry (TDR) used to measure the soil moisture. Before the experiment, the physicochemical properties of the soil measured. The measured morphological traits included leaf area, percentage of leaf abscission, and shoot fresh and dry weight. These traits measured four months after subjecting to water stress. The evaluated physiological traits included electrolyte leakage (EL), relative leaf water content (RWC), leaf chlorophyll, proline and malondialdehyde (MDA). These traits also measured four months after subjecting to water stress. The experiment conducted in split plots based on a randomized complete block design in three replications and four seedlings in each experimental unit. The main plot included water drought treatments and the sub plot included almond cultivars. Data analysis carried out using SAS software version 9.2 and comparison of mean data conducted based on LSD test at a five percent probability level.
Results and Discussion
As the intensity of drought stress increased, the fresh and dry weight of shoot decreased in almond cultivars and GN rootstock. At soil humidity of 10% field capacity, Shahroud 8 showed higher amounts of shoot fresh weight (785 g). The lowest fresh and dry weight of the shoot and the highest leaf abscission were observed under severe drought stress (10% of the field capacity) in Shahroud 13. The increase in drought levels led to a decrease in the leaf area in the studied cultivars and rootstock of almond. Shahroud 8 had more chlorophyll content than other cultivars at the most severe stress level, and Shahroud 13 showed the lowest chlorophyll b content at 10% humidity of field capacity. A significant decrease in leaf chlorophyll concentration under drought stress has also been reported in previous research (Schlemmer et al., 2005; Gohari et al., 2023). A further decrease in chlorophyll could be due to a drastic decrease in RWC under severe stress conditions. According to Ranjbar et al. (2022), the amount of RWC decreased by 32 to 44% under stress conditions in the K13-40 grafted cultivar on the rootstock of bitter almond No. 32. In the current research, the biggest decrease in RWC was in Shahroud 13 with a decrease of 36.85%. The lowest decrease in RWC was also observed in the GN rootstock with a decrease of 20.94%. Shahroud 13 and GN rootstock showed the highest and lowest electrolyte leakage at the highest stress level, respectively. Karimi et al. (2013) also found a significant increase in EL in White, Mamai and Ferragnes cultivars due to the higher sensitivity of these cultivars to water loss. The most difference in MDA value was observed in Shahroud 13 with an increase of 186.35% and the lowest difference was found in Shahroud 10 with an increase of 84.58%. Shahroud 6 produced the highest content of proline under severe water stress. According to the results, Shahroud 13 and then Shahroud 6 were recognized as the most sensitive cultivars. Shahroud 8 and 12 were among the tolerant cultivars. Other cultivars were also between these two groups.
Conclusions
Shahroud 13 was recognized as the most sensitive cultivar with the lowest fresh and dry weight, RWC and the highest ion leakage and MDA at the most severe stress level. After that, Shahroud 6 had high sensitivity. Shahroud 8 was recognized as the most drought tolerant cultivar due to its lowest MDA content, the highest chlorophyll a and b and RWC in the most level of drought. After Shahroud 8, Shahroud 12 was including the tolerant cultivars. Tolerant cultivars can be used in future studies to evaluate the possibility of planting these cultivars in areas with water shortage problems.
Maryam Tatari; Mehrdad Mahlouji; Ebrahim Ghorbani
Abstract
Introduction: The evaluation of storage characteristics and determination of resistance to post-harvest disorders in horticultural crops is highly important. ‘Viduja’ as new quince cultivar and KVD2 and KVD4 promising quince genotypes were collected from different regions of Isfahan Province. As ...
Read More
Introduction: The evaluation of storage characteristics and determination of resistance to post-harvest disorders in horticultural crops is highly important. ‘Viduja’ as new quince cultivar and KVD2 and KVD4 promising quince genotypes were collected from different regions of Isfahan Province. As these cultivar and promising genotypes are new, it is necessary to determine the most appropriate harvest time for them based on effective harvest indices. This research was carried out for the determination of the best harvest time and storage period of these promising quince cultivar and genotypes.
Material and Methods: This experiment was carried out on 'Viduja' as new cultivar and KVD2 and KVD4 genotypes as promising genotypes and 'Isfahan' cultivar as control, which was grafted on hawthorn seedling rootstock. In April, the full bloom time of these cultivars and genotypes was monitored to report harvest time based on the number of days after flowering for each cultivar and genotype. Fruits were harvested on October 6th, 14th, and 21th, 2016 in the horticultural research station of Mobarakeh. Fruits were transferred to cold storage with 0±1°C and 90±5% R.H. for five months. Some traits were measured in the harvesting date and also at the end of every month. These traits included weight loss percentage, fruit firmness, TSS, TSS/TA, pectin, total phenol, surface browning and decay percentage. The experiment was carried out as a factorial experiment in a completely randomized design with three replicates (10 fruits in each replicate).
Results and Discussion: 'Viduja' cultivar and KVD2 and KVD4 genotypes were early flowering and had similar flowering time. Isfahan quince cultivar was late flowering and had moderate overlap with KVD2 and KVD4 genotypes. According to the results, the highest weight loss was observed in the fifth month of storage. In this month, 'Isfahan' and 'Viduja' cultivars showed the most and the least weight loss, respectively. Others showed increased water loss and reduced fruit weight with increased storage time. For example, with increasing the duration of storage in the cold storage, the weight loss of 'Gorton' quince cultivar increased. In all cultivars and genotypes, the highest TSS and TSS/TA were founded in the third harvest and fifth and fourth month of storage. Mosharraf and Ghasemi (34) reported that TSS in the last harvesting time and after five months of storage time was 20.16% in 'Isfahan' cultivar. In their research, TSS was 14.75% in harvesting time that was less than the rate of this trait in the current study. The highest TSS/TA belonged to 'Isfahan' and 'Viduja' cultivars. The highest fruit firmness was obtained at harvest time of 'Isfahan' and KVD2 genotype, and the lowest of that was observed in five months after the storage of KVD4 genotype. In the Esme quince cultivar, the fruit firmness in the third harvest quickly decreased, and after six months it was 3 kg cm-2. At harvesting time of KVD4 genotype, the highest phenol content was observed. 'Isfahan', 'Viduja' cultivars and KVD2 genotype showed the lowest phenol content after five months of storage. Increasing the storage period resulted in a decrease in phenol content in all cultivars and genotypes. Similarly, other researchers showed that the total phenol content gradually decreased with prolonged fruit storage (6 and 7). KVD4 genotype and 'Isfahan' cultivar showed the most pectin content at harvesting time. Increasing the storage time reduced the rates of pectin. According to Mosharraf and Ghasemi (39), increased storage period reduces pectin content in Isfahan cultivar fruits. The fruit surface browning was begun from the fourth month of storage, and there was no significant difference with the amount of this trait in the fifth month. Surface browning in the third harvest of Esme cultivar was also more than the previous harvestings, and eventually reached 70% (30). With prolonging storage time, the decay percentage increased. The first decay was observed from the third month of storage and reached its highest level in the fifth month. Isfahan cultivar had the highest percentage of decay. Other cultivar and genotypes had no significant difference in decay percentage.
Conclusions Finally, the best harvesting time for 'Isfahan', 'Viduja', KVD2 and KVD4 cultivars and genotypes were 185, 200, 200 and 193 days after full bloom respectively. Fruit storage in the cold for four months is advisable for 'Isfahan' and 'Viduja' cultivars and KVD4 genotype. In KVD2 genotype fruits, five-month storage is recommended.
