Alternate Bearing Research Articles

Mango (Mangifera indica L.) Cultivars with Alternate Bearing Tendencies were Subjected to Physio-Chemical, Nutritional and Enzymatic Assays

Mango (Mangifera indica L.) Cultivars with Alternate Bearing Tendencies were Subjected to Physio-Chemical, Nutritional and Enzymatic Assays

Physiological and molecular insights into the alternate bearing in mango (Mangifera indica L.) using next-generation sequencing approaches.

India's mango productivity is hindered by many factors but more importantly due to limited understanding of the genomic complexities behind regular bearing habit. This study is the first to quantify carbohydrate fractions, protein content, and macro and micronutrient storage pools, their transportation, and contributions to regular 'Totapuri' and alternate bearer 'Bombay Green' mango varieties during the 'off' year. Deep RNA sequencing was used to assess gene expression dynamics between buds and flowers of these varieties. Differential pathway analysis showed the greatest number of differentially expressed genes in metabolic processes (1377), followed by oxido-reductase (879), hormone (80), oxidative stress (77), starvation (39), alternate bearing (8), flowering (3), meristem (3), and cellular component (2) pathways. In silico analysis showed that among 15 genes, twelve genes up-regulated in Totapuri and three in Bombay Green, confirmed by qRT-PCR. Additionally, 202 SNPs were identified in 32 alternate bearing-related genes. The study confirmed the reproductive bud's strong ability to import sugars, protein, and starch in the regular bearer variety, enhancing flowering and fruiting during off years. The mineral nutrients and biochemical constituent of the bud and leaf tissue in contrasting genotypes, showed the potential role for regular bearing in mango.

Pattern of flower and fruit abscision and fruit growth of hass avocado under tropical conditions

Research elucidating abscission processes in fruits of Hass avocados has been conducted in production areas in the subtropics, but there are few studies under tropical climate conditions that can serve as a starting point to guide suitable management practices. In a seven-year-old commercial orchard of Hass avocados, grafted onto native rootstocks (Antillean rootstocks), 20 trees were evaluated. A weather station installed on-site monitored the climate of the location. The pattern of fruit growth and development, flower and fruit abscission, and yield variables were characterized. More than 145,000 and 270,000 flowers abscised per tree were recorded, with final fruit sets of 0.1 ± 0.009% and 0.19 ± 0.04% in the first and second crop years, respectively. Fruit growth followed a sigmoid curve with no differences in growing degree-days until the time of harvest. Additionally, the alternate bearing behavior of Hass avocado was confirmed with an average yield of 24.3 ± 4.5 kg/tree and 93.3 ± 9.5 kg/tree for the first and second crop years, respectively, finding an average alternate bearing index of 0.74 ± 0.06.

Leaf gas exchange, water use, and yield of Marula (Sclerocarya birrea) and Kei Apple (Dovyalis caffra): South African indigenous fruit trees with domestication potential

Conventional crop production is expected to decline in the future in sub-Saharan Africa due to the rising costs of inputs, soil degradation, and increasing water scarcity related to climate variability and change. South Africa has more than 30 species of indigenous fruit trees that are adapted to grow under harsh conditions, yet these species are currently underutilized. Their cultivation is constrained by the lack of detailed ecophysiological information required to develop effective management strategies that optimize tree performance. In this study we investigated how two species with domestication potential namely Marula (Sclerocarya birrea) and Kei apple (Dovyalis caffra) responded to climate and soil factors over a period of two years (2019–2021). Photosynthesis, transpiration, and yield were quantified for mature trees growing in experimental orchards in the Mpumalanga Province of South Africa. Leaf gas exchange data were collected at selected intervals during the growing season using an infrared gas analyser while whole tree transpiration rates were quantified using the heat ratio method of monitoring sap flow. These data were used to parameterize a big leaf Penman-Monteith (PM) model to estimate the transpiration dynamics of individual trees at the daily time step. S. birrea's transpiration responded strongly to both climatic and soil water content variations while the water use of D. caffra was driven mostly by climatic factors. Transpiration rates averaged 0.30 L/m2 of leaf area for S. birrea while that of D. caffra was around 0.45 L/m2. Both species exhibited significant alternate bearing with yield of individual trees fluctuating by more than 50 % between successive years. For the 2019/20 season, water productivity (grams of fruit per litre of water transpired) varied between 6.2 and 17.4 g/L for S. birrea and between 24.3 and 41.7 g/L for D. caffra. Whole tree transpiration by both species were accurately predicted using the PM model albeit with different parameters for each species. This study demonstrates that a simple PM model can accurately estimate the water requirements of these species in other growing regions.

Productivity and Vigor Dynamics in a Comparative Trial of Hedgerow Olive Cultivars

The hedgerow growing system is prevalent in new olive orchards worldwide due to its fully mechanized harvesting. Several works have been published to compare cultivars planted in this system, focusing on productivity and oil composition. However, little research has been conducted on the long-term evaluation of cultivars’ growth habits when trained in hedgerow systems and on how it affects their interannual productivity. In this work, we report the canopy growth habit, productivity, and their correlation for the ‘Arbequina’, ‘Arbosana’, ‘Koroneiki’, ‘Lecciana’, ‘Oliana’, and ‘Sikitita’ cultivars grown in a hedgerow system in Extremadura, central-western Spain, for 9 years. ‘Koroneiki’, ‘Arbequina’, and ‘Lecciana’ were the cultivars with the highest canopy growth, both in young and adult trees, and the ones with the highest pruning needs from 5 to 10 years after planting. The yield behavior in each of the years evaluated was stable in all cultivars except ‘Lecciana’. This alternate bearing was associated with the distribution of total yearly produced biomass between fruits and vegetative growth. ‘Oliana’, ‘Arbosana’, and ‘Sikitita’ were the cultivars with the highest proportion of fruit of the total biomass, and ‘Lecciana’ showed the lowest. This study indicates that cultivars with higher fruit proportions of total biomass might have better suitability for long-term growing in hedgerow formation, fewer pruning needs, and more stable productivity across the years. In this sense, in the climatic conditions considered here, ‘Arbosana’, ‘Sikitita’, and ‘Oliana’ could be the most suitable cultivars for this growing system.

Quantitative variation of phenolic compounds in different tissues of pistachio(Pistacia vera L. cv. Uzun) associated with alternate bearing

Quantitative variation of phenolic compounds in different tissues of pistachio(Pistacia vera L. cv. Uzun) associated with alternate bearing

Alternate bearing in 'Hass' avocado: fruit load-induced changes in bud auxin homeostasis are associated with flowering repression.

In 'Hass' avocado (Persea americana), fruit presence reduces next season flowering. Recent fruit tree studies proposed that heavy fruit load (HFL) generates an auxin (indole-3-acetic acid, IAA) signal in the buds that represses flowering. However, the nature of this signal remains unknown. Here, we investigated the effect of avocado HFL on bud IAA accumulation and flowering transition. We found that IAA-aspartate and IAA-glutamate conjugate levels were significantly higher in buds from fully loaded ('on') than low-loaded ('off') trees, hinting that free IAA levels were higher in the former. Expression analysis showed that coinciding with flowering reduction, HFL induced the floral repressor PaTFL1, and suggested that accumulation of IAA in buds as imposed by HFL was associated with its conjugation to aspartate and glutamate and resulted both from de novo IAA synthesis and from reduced IAA export. Accordingly, experiments involving radiolabelled [14C]IAA demonstrated that HFL reduced shoot basipetal IAA transport. Finally, we confirmed the negative effects of IAA on flowering, showing that IAA and polar auxin transport blocker (2,3,5-triiodobenzoic acid) treatments delayed 'off' trees' inflorescence development, reducing their inflorescence axis and inducing PaTFL1 expression. Together, our data indicate that avocado HFL generates IAA signalling in buds that induces PaTFL1, leading to repression of inflorescence development.

Monitoring multiyear individual tree flowering and yield reveals high variation among ‘Pinkerton’ avocado trees

ABSTRACT Most avocado cv. Pinkerton scions in Israel are grafted on seedling rootstocks, resulting in unstable yields. The objective of this study was to evaluate tree multiyear yield variation among ‘Pinkerton’ trees. We evaluated the flowering and yield variations among trees in two commercial avocado orchards, in Kibbutz Dan and Kibbutz Kfar-HaNassi, for 4 years. The multiyear average yield of the individual trees ranged from 9.5 to 73.7 kg tree−1 in Dan, and 1.7 to 53.8 kg tree−1 in Kfar-HaNassi, with coefficient of variation (CV) of 42% and 54%, respectively. Multiyear flowering intensity ranged from 2.7 to 4.9 and 2.41 to 5 (out of 5), with generally lower CV values of 14% and 26%, respectively. Multiyear alternate bearing index (ABI) ranged from 0.24 to 0.85 and 0.2 to 1, with CV of 25% and 32%, respectively. In Dan, the yield was negatively correlated with ABI. In Kfar-HaNassi, the yield was positively correlated with flowering intensity and negatively correlated with ABI. These results show that it may be important to monitor long-term individual tree yield, because removing low-yielding trees and selecting genetic material characterised by high yield and low ABI may be advantageous for establishing orchards with stable high yields.

Elevated nitrogen fertilization differentially affects jojoba wax phytochemicals, fatty acids and fatty alcohols.

Jojoba wax is gaining popularity among cosmetics consumers for its skin wound healing and rejuvenation bioactivities, attributed to collagen and hyaluronic acid synthesis. However, information regarding wax phytochemical composition and quality parameters, as well as effect of cultivation practices, and fertilization in particular, on wax quality is limited. The aim of the current work was to study the effect of nitrogen (N) availability to jojoba plants on wax phytochemical composition and beneficial skin-related contents. For this, wax quality from a six-year fertilization experiment with five N application levels was evaluated. The chemical parameters included antioxidant activity, free fatty acid, total tocopherol, total phytosterol and oxidative stability, as well as fatty acid and fatty alcohol profile. Our results reveal that the majority of wax quality traits were affected by N fertilization level, either positively or negatively. Interestingly, while fatty acids were unaffected, fatty alcohol composition was significantly altered by N level. Additionally, fruit load also largely affected wax quality, and, due to jojoba's biennial alternate bearing cycles, harvest year significantly affected all measured parameters. Results shed light on the effects of N application on various biochemical constituents of jojoba wax, and imply that N availability should be considered part of the entire agricultural management plan to enhance wax quality. Some traits are also suggested as possible chemical quality parameters for jojoba wax.

Exploring Carbohydrate Concentration Fluctuations in Pistachio (Pistacia vera L. cv Uzun) for Deeper Insights into Alternate Bearing Patterns

Alternate bearing (AB) is of great importance in horticulture and leads to fluctuations in yield variation. Although AB is a natural phenomenon to optimize resource allocation and improve crop productivity and profitability in plants, understanding the factors that influence AB can help in implementing effective management strategies to reduce the negative effects and promote consistent and sustainable production. This study aimed to investigate the variation in carbohydrate levels in various tissues of both bearing and non-bearing pistachio (Pistacia vera L. cv Uzun) trees during different periods of growth development in two consecutive years to gain a deeper understanding of their potential contribution to AB. Twelve 34-year-old pistachio trees, consisting of six “ON” and six “OFF” year trees, were accidentally selected from a pistachio orchard. The “OFF” year trees were induced two years before sampling to be in the “OFF” year state by artificially removing flower buds. Sucrose was the main soluble sugar in the different parts of the pistachio tree studied. In general, the amount of sugar was higher in the non-bearing year than in the bearing year. It was found that non-structural carbohydrates of trees decreased between June and July, resulting in flower buds to abscise. The amount of carbohydrates decreased during nut development in “ON” trees, indicating the possible role of carbohydrates in AB.

Alternate Bearing and Chemical Thinning Applications in Olives

In this review, in which the subject of alternance in olives is discussed, the effect of alternance on olive cultivation and the methods of coping with alternans are examined in line with the latest literature. The latest developments in chemical dilution, which is the most effective and most practical among alternative methods of combating alternance, are brought together. Chemical dilution studies on olives conducted in 2021 and before were searched for and presented in this review using various databases. As a result of the literature review, access to 20 scientific research articles directly related to the subject was provided. Because of the alternate bearing discussed in the study, olive production follows a cyclical pattern. Despite the fact that the olive is genetically predisposed to alternate bearing, it can be managed and controlled through horticultural practices; in this regard, chemical fruit thinning is the most commonly used method in olives. NAA, NAAm, Ethephon, Urea and GA3 are among the most preferred chemicals used for chemical dilution in olives. Chemicals used, their doses, application times and many factors related to them affect the success of chemical applications. These factors include the tree’s age, variety, physiological condition and climatic conditions (particularly temperature), full flowering time, and young fruiting period. When we look at the publications on chemical dilution, it is striking that the studies in our country are fewer in number than the studies abroad. This situation can be associated with the fact that there are still some concerns about chemical dilution in our country. The availability of “environmentally friendly” chemicals will be beneficial in reducing these concerns and protecting the environment, and producers will not suffer economically. As a result, there has been an increase in the use of chemicals all over the world in recent years, with an increasing reputation for environmentally friendly chemicals.

A Systematic Review of the Clinical Efficacy of Oxidized Zirconium as a Bearing Surface in Hip Arthroplasty

Background Total hip replacement (THA) is an established treatment for end stage hip arthritis providing reliable pain free function. The long-term survival of THA depends on multiple factors, But aseptic loosening and wear induced osteolysis are most common causes of failure and search for alternative bearing surfaces became an important issue. Aim of the Work Our aim in this study is to evaluate efficacy of Oxide zirconium femoral head as a bearing surface in Total hip arthroplasty patients regarding clinical and radiological outcomes. Patients and Methods The types of study was a prospective and retrospective comparative cohort studies. Search results were conducted to systematic review management software and manually screened for eligibility to be included. PRISMA flowchart was produced based on the search results and the inclusion/exclusion criteria. Results OxZr was found to be less sensitive than CoCr to these variations and maintained a lower coefficient of friction when articulated with UHMWPE, even in poor lubricants. Conclusion Most of studies which were included in this review reported no significant differences in the mean polyethylene wear rate, survival rate, mean postoperative clinical subjective scores and complications’ rate of patients treated with OxZi femoral heads compared with the respective mean wear values of those who treated with CoCr femoral heads, While OxZi is offered at a cost premium, it seems that this type of alternate bearing surface is not clinically superior to the traditional metal bearing surface inTHA.

Germplasm Diversification in Citrus Orchards in a Mesothermal Climate in Brazil

The limited scion-rootstock combinations used in sweet orange orchards in Brazil reduce the commercial potential of citrus and lead to greater susceptibility to pests and diseases. Aiming to provide germplasm diversification, the research evaluated the Folha Murcha (FM) and Charmute de Brotas (CB) orange trees grafted onto ‘Rangpur’ lime (RL) and ‘Swingle’ citrumelo (SC) rootstocks. The study was conducted in the southern center of the state of São Paulo, in the subtropical region of southeastern Brazil. The grafted trees were planted in September 2016. The field experiment was conducted over two seasons. The combinations were evaluated based on the duration in days and degree-days of the phenological intervals, growth and yield performance, alternate bearing, fruit ripening, and quality. The trees of the two scion cultivars grafted onto RL had the shortest crop cycle, the earliest fruit ripening, and the largest canopy volume. SC produced fewer alternate bearings with greater production efficiency. The CB/SC combination produced fruits with a better color index, higher total soluble solids content, and a higher technological index. This assessment can be useful in planning orchards for dual-purpose markets, such as table fruit and the juice industry.

Effects of fruit load on growth, photosynthesis, biochemical characteristics, and fruit quality of Camellia oleifera

Camellia oleifera Abel is one of the four major woody oil species that produce edible oil from seeds. Nevertheless, its oil yield is comparably low, due to an imbalance in its source–sink relationship caused by its alternate bearing cycle. In this study, we conducted a pot experiment using 5-year-old C. oleifera ‘Huaxin’ young plants to examine the source–sink relationship and determine the optimal fruit load for oil production that ensures maximum economic value for C. oleifera. From April to October, the C. oleifera young plants were subjected to different leaf:fruit ratios: no fruit (control, CK), low fruit load (FL1, leaf:fruit ratio of 36:1), medium fruit load (FL2, leaf:fruit ratio of 18:1), and high fruit load (FL3, leaf:fruit ratio of 9:1). The results showed that the FL2 and FL3 treatments significantly reduced plant height, stem diameter, and flower bud differentiation from August to October, compared with the control. The net photosynthetic rate (Pn) and stomatal conductivity (Gs) of new leaves on clear days from June to August were decreased in the FL2 and FL3 treatments, compared with the control. Medium and high fruit loads (FL2 and FL3 treatments) and prolonged growth duration led to greater reductions in fruit size, weight, seed kernel oil content, oil production per plant, oil body volume, and distribution area, compared with the FL1 treatment. However, stearic acid and oleic acid contents were significantly higher in camellia oil obtained from the FL1 treatment than in camellia oil obtained from the FL2 and FL3 treatments. Thus, a leaf:fruit ratio of 36:1 is recommended to ensure proper C. oleifera ‘Huaxin’ growth and yield, and higher fruit loads should be avoided.

Comparative Evaluation of Date Palm Types (Phoenix dactylifera L.) under the Conditions of the Northern State, Sudan

This study was accomplished to assess the comparativeperformance of the dry, semi-dry and soft date palm types under theconditions of the Northern State, Sudan. Four date representativecultivars, grown in Elghaba Agricultural Scheme, were compared;.theirage ranged between 30 and 34 years. The cultivars were Barakawi andGondaila (dry), Wadkhteeb (semi-dry) and Madina (soft). Data recordedfor vegetative growth parameters were stem circumference, leaf numberand length, number of pinnae/leaf, length of pinnae, number of thorns/leafand width of leaf base. Data were also collected for number of bunches,bunch weight and yield/palm. The results indicated significant differencesbetween the four cultivars. Wadkhteeb excelled the other cultivars innumber of leaves, bunch weight and yield/palm, without being affected bythe phenomenon of alternate bearing. The superiority of Wadkhteeb inyield is indicative of the suitability of the semi-dry cultivars to theconditions of the Northern State.

Delayed harvesting during one season reduces yield of next year’s crop and induces alternate bearing in mango cv. Sammar Bahisht Chaunsa

Delayed harvesting during one season reduces yield of next year’s crop and induces alternate bearing in mango cv. Sammar Bahisht Chaunsa

Evaluation of Pecan [Carya illinoinensis (Wangenh.) K. Koch] Cultivars for Possible Cultivation for Both Fruit and Truffle Production in the Puglia Region, Southeastern Italy

Yield and different nut parameters were measured for two growing seasons on mature (28–29 years) trees of 11 pecan cultivars grown in an experimental orchard located in the Puglia Region, Southeastern Italy. ‘Shoshoni’ and ‘Shawnee’ pecan seedlings were inoculated with three truffle species (Tuber borchii—known as the ‘whitish truffle’, T. aestivum—called the ‘summer truffle’, and T. melanosporum—the common ‘Black truffle’) and investigated for six months. The level of ectomycorrhizal colonization was assessed 6 and 12 months after inoculation. Results indicated that ‘Wichita’, ‘Shoshoni’, and ‘Pawnee’ performed well in the pedoclimatic conditions of the area with a yield higher than 20 kg/tree and a kernel dry weight of ≅3 g. These preliminary yield results suggested that some pecan cultivars could deserve consideration for cultivation in the Puglia Region, whereas others with low yield and a stronger alternate bearing should not be considered. Plant height, number of leaves, chlorophyll content (expressed as a SPAD unit) and stem diameter partially indicated the increase in ecological fitness in truffles-inoculated plants. Successful mycorrhization indicated ‘Shoshoni’ and ‘Shawnee’ as suitable to establish ectomycorrhizal symbiosis with T. aestivum, T. borchii, and T. melanosporum cultivation under Puglia climatic conditions. The results also showed that the applied protocol was adequate to obtain healthy mycorrhized seedlings appropriate for commercialization and plantation for truffles production on pecan in the future.

Comparative transcriptomics in alternate bearing cultivar Dashehari reveals the genetic model of flowering in mango.

Flowering is a complex developmental process, with physiological and morphological phases influenced by a variety of external and internal factors. Interestingly, many mango cultivars tend to bear fruit biennially because of irregular flowering, and this has a negative impact on mango flowering and the subsequent yield, resulting in significant economic losses. In this article, transcriptome analysis was carried out on four tissues of mango cv. Dashehari (bearing tree leaf, shoot apex, inflorescence, and non-bearing tree leaf). De novo transcriptome assembly of RNA-seq reads of Dashehari using the Trinity pipeline generated 67,915 transcripts, with 25,776 genes identified. 85 flowering genes, represented by 179 transcripts, were differentially expressed in bearing vs. non-bearing leaf tissues. Gene set enrichment analysis of flowering genes identified significant upregulation of flowering related genes in inflorescence tissues compared to bearing leaf tissues. The flowering genes FT, CO, GI, ELF 4, FLD, FCA, AP1, LHY, and SCO1 were upregulated in the bearing leaf tissues. Pathway analysis of DEGs showed significant upregulation of phenylpropanoid and sucrose and starch pathways in non-bearing leaf tissue compared with bearing leaf tissue. The comparative transcriptome analysis performed in this study significantly increases the understanding of the molecular mechanisms driving the flowering process as well as alternative bearing in mango.

Alternate Bearing in Fruit Crops: Causes and Control Measures

Alternate bearing (AB) is a phenomenon, common in fruit crops, is a concerned plant or branch or orchard does not bear a regular crop year-after-year rather heavy yields are followed by extremely light yield and vice versa. Based on the alternate bearing index, it is divided in four groups viz., no alternation, less alternate, high alternate, severe alternate. There are mainly two factors are responsible for alternate bearing i.e., exogenous and endogenous factors. Alternate bearing can be managed by cultural practices, selection of rootstocks, and selection of cultivars, chemical application and pruning at right time. Scrutiny of all of the factors are presented in this review to achieve consistent success in induction of flowering in perennial fruit crops. The information may pave way for better regulation of flowering shoots to enhanced fruit productivity in various fruit crops.

Alternate Bearing Tendency in Gamma-Ray Induced Mutants of ‘Amasya’ Apple

Alternate Bearing Tendency in Gamma-Ray Induced Mutants of ‘Amasya’ Apple