Defining the physiological and molecular threshold of source–sink balance governing yield and sugar metabolism in ‘mazafati’ date palm (Phoenix dactylifera L.)

Water yam ( Dioscorea alata L.) growth and yield as affected by the planting date: Experiment and modelling

Effect of number of suckers on date palm source-sink limitation tracked by physiological markers and carbon allocation responsive genes expression

Optimizing the leaf-to-bunch ratio in ‘Mazafati’ date trees by considering source-sink limitation and physiological-molecular responses

Split-split plots experimental design based on randomized complete block design was conducted at the Baiekola Agricultural Research Center in 2010 to study the effects of changes in source–sink on the yield and yield components of soybean cultivars planted at different dates. Factors studied in this experiment included planting date, as the main plot, at two levels (June 6, June 27), cultivars (Line 032, 033, Sari or JK, and Telar or BP), as the sub plot, and five levels (including the removal of the top, the middle, and the bottom one thirds of the leaves, removal of one third of the flowers, and the control treatment as the sub-sub plot. Results of analysis of variation showed that the various cultivars were significantly different in all the studied traits at (P<0.01) probability level. Seed yield at the first planting date (184.03 g. m-2) was 11.18% lower than that at the second planting date (163.45 g.m-2). The highest seed yield was obtained in Line 033 with 219.96 g.m-2, which was statistically different from the those of all the other cultivars except that of Line 032, which was 186.19 g.m-2. The higher seed yields in Line 033, as compared with other treatments, were accompanied by the highest 1000 seed weight (242.93 g), the highest number of pods per plant on the main stem (43.31) and on the auxiliary stems (33.37), and the relatively high number of seeds per pod (2.37). Results of applying limitations of the sink–source treatments on seed yield showed that the highest seed yield was obtained in the control treatment (212.17 g.m-2). With the removal of the top one third of the leaves, the yield decreased severely so that the least seed yield in this treatment (138.08 g.m-2) was 35% less than that of the control. In the treatments of removing the middle one third of the leaves and one third of the flowers, the seed yield was reduced by 28.5 and 21.8%, respectively, as compared with the control. The least effect on seed yield was observed in the treatment of removing the bottom one third of the leaves, in which the yield was 201 g.m-2, or only 5.25% less than that of the control. The high yields in the control treatment of applying sink–source limitations were accompanied by high 1000 seed weight (220.217 g), the maximum number of seeds per pod (2.53), the maximum number of pods on the main stem (46.40), and, finally, the maximum number of pods per stem (74). The least seed yield in applying the treatment of the removal of the top one third of the leaves was also accompanied by the least 1000 seed weight (199.59 g), the fewest number of seeds per pod (2.27), the fewest number of pods per main stem (30.62), and the fewest number of pods per plant (53).

The effect of planting date on maize grain yields and yield components

This study was aimed to investigate the appropriate planting date and tolerance to adverse growing conditions in the spring season through seeds stimulation technology. A field experiment was carried out in the spring seasons of 2022 and 2023 according to a randomized complete block design in a split-plot arrangement with four replications. The main factor is planting dates (February 15th, March 1st and 15th, and April 1st and 15th). The secondary factor is seeds stimulation (potassium nitrate 6 mg L-1 + licorice extract 6 g L-1, as well as soaking with distilled water only). The stimulated seeds (potassium nitrate + licorice extract) and the planting date of February 15th were superior in traits of fertility ratio, number of grains per ear, weight of 300 grains, total grains yield, biological yield, and harvest index in both seasons (2022 and 2023). The stimulated seeds (potassium nitrate + licorice extract), planted on February 15th, excelled in the traits above (95.6 and 97.7%), (640.7 and 816.9 grain ear-1), (76.19 and 82.69 g), (7.2 and 7.8 ton ha-1), (17.5 and 18.9 ton ha-1) and (41.5 and 41.2%) in both seasons, respectively. It can be concluded that seeds stimulation improved the yield and its components of corn crop under a wide range of environmental conditions, and that planting the stimulated seeds on February 15th contributed to take advantage of the prevailing environmental conditions and regulating the relationship between source efficiency and sink capacity to obtain the highest grain yield. It can be recommended that soaking the seeds with potassium nitrate 6 mg L-1 + licorice extract 6 g L-1 together when planting in mid-February in the spring season to increase grains yield.

The carbohydrate evaluation of organs (fruit, leaflet and root) at important physiological stages (three peaks of fruit abscission, harvest and before flower induction) on 60 ‘Mazafati’ date palm (Phoenix dactylifera L.) trees in five groves with a history of alternate bearing disorder showed that leaflet starch content before flower induction was the best physiological marker for early detection of this disorder based on both the biennial bearing index (BBI) and fruit bunch number. The differences in carbohydrate between organs in different loading trees were not due to differences in the chlorophyll pigments and photosynthesis rate and were the affect of different loadings on source–sink regulation. The 2-year leaf spray of trehalose disaccharide before flower induction stage on Off trees by activating oxidative stress, increasing leaf hydrogen peroxide index, indicated that these loading differences were due to changes in the allocation of carbohydrate types between organs at this stage. The changing carbohydrate allocation pattern in favor of increasing the leaflet starch compared to other two organs before flower induction by trehalose treatment while increasing flower induction in the Off trees, increasing the bunch number, resulted in controlling the alternate bearing to improve annual production indices and preserving the physicochemical properties of the fruit consistent with the non-alternate bearing trees.

The effect of planting date on maize: Phenology, thermal time durations and growth rates in a cool temperate climate

Date palm (Phoenix dactylifera L.) is a cultivated woody plant species with agricultural and economic importance. Here we report a genome assembly for an elite variety (Khalas), which is 605.4 Mb in size and covers >90% of the genome (~671 Mb) and >96% of its genes (~41,660 genes). Genomic sequence analysis demonstrates that P. dactylifera experienced a clear genome-wide duplication after either ancient whole genome duplications or massive segmental duplications. Genetic diversity analysis indicates that its stress resistance and sugar metabolism-related genes tend to be enriched in the chromosomal regions where the density of single-nucleotide polymorphisms is relatively low. Using transcriptomic data, we also illustrate the date palm’s unique sugar metabolism that underlies fruit development and ripening. Our large-scale genomic and transcriptomic data pave the way for further genomic studies not only on P. dactylifera but also other Arecaceae plants.

As climate changes, temperatures will play an increasing role in determining crop yield. Both climate model error and lack of constrained physiological thresholds limit the predictability of yield. We used a perturbed-parameter climate model ensemble with two methods of bias-correction as input to a regional-scale wheat simulation model over India to examine future yields. This model configuration accounted for uncertainty in climate, planting date, optimization, temperature-induced changes in development rate and reproduction. It also accounts for lethal temperatures, which have been somewhat neglected to date. Using uncertainty decomposition, we found that fractional uncertainty due to temperature-driven processes in the crop model was on average larger than climate model uncertainty (0.56 versus 0.44), and that the crop model uncertainty is dominated by crop development. Simulations with the raw compared to the bias-corrected climate data did not agree on the impact on future wheat yield, nor its geographical distribution. However the method of bias-correction was not an important source of uncertainty. We conclude that bias-correction of climate model data and improved constraints on especially crop development are critical for robust impact predictions.

The study of clinical electrophysiology essentially comprises examining how electric excitation develops and spreads through the millions of cells that constitute the heart. Given the enormous number of cells in a human heart, there is an extremely large number of possible ways that the heart can behave. We encounter rhythms across the spectrum from the organized and orderly behavior of sinus rhythm through repetitive continuous excitation (via reentry) in structurally defined circuits like atrial flutter and, finally, the complex, dynamic, and disorganized behavior of fibrillation. Despite these myriad possibilities, one can apply a basic understanding of the principles of propagation to predict how cardiac tissue will behave under varied circumstances and in response to various manipulations. In this article, we review the principles of propagation and how these can be used to understand reentry of all degrees of complexity. We use these principles to explain the mechanisms by which antiarrhythmic medications and ablation can terminate and prevent reentry. This article is not intended to be an exhaustive description of the physiology of cardiac propagation, rather, it is meant to capture the essence of propagation with sufficient detail to provide an intuitive feel for the interplay of the physiological features relevant to propagation. The figures and videos used in this article were created using a computational model of cardiac propagation (VisibleEP LLC, Colchester, VT). It is a hybrid between a physics-based and cellular automaton model. The model incorporates the fundamental features of propagation without modeling individual ion channels.1 The model manifests several relevant emergent properties, for example, electrotonic interactions, restitution of action potential duration, and conduction velocity as well as source–sink balance–dependent propagation. ### Cell Excitation A cell becomes excited when the balance of inward and outward currents passes a critical point after which inward currents exceed outward and an action potential ensues. …

While substantial effort has been expended on molecular techniques in an attempt to break through the apparent ceiling for sucrose content (SC) in sugarcane stalks, molecular processes and genetics limiting sucrose accumulation remain unclear. Our own studies indicate that limiting expansive growth with water stress will enhance sucrose accumulation in both low- and high-sucrose clones. Sucrose accumulation was largely explained (72%) by an equation with terms for photosynthesis, plant extension rate (PER), and plant number. New research was conducted to determine if this simple model stands when using temperature rather than water stress to perturb the source–sink balance. We also applied a thinning treatment to test the proposal implicit in this equation that SC will increase if competition between plants for photo-assimilate is reduced. Four clones from a segregating population representing extremes in SC were planted in pots and subjected to warm and cool temperature regimes in a glasshouse facility. A thinning treatment was imposed on half the pots by removing all but 6 shoots per pot. Temperature as a means of reducing sink strength seemed initially to be more successful than water regime because PER was 43% lower in the cool than in the hot regime while photosynthesis was only 14% less. PER was a good indicator of dry matter allocation to expansive growth, limited by water stress but not by temperature, because stalks tended to thicken in low temperature. Thinning had little effect on any of the attributes measured. Nevertheless the clonal variation in plant numbers and the response of PER to temperature helped to explain at least 69% of the variation in sucrose accumulation observed in this experiment. Thus the earlier model for sucrose accumulation appeared to be valid for the effect on sucrose accumulation of both temperature and water stress on the source–sink balance. The next step is to include internodes in models of assimilate partitioning to help understand the limiting steps in sucrose accumulation from the basics of source–sink dynamics.

Evaluation of Commercial and Field-Expedient Baited Traps for House Flies,<i>Musca domestica</i>L. (Diptera: Muscidae)

A comparison of nine commercial baited fly traps on Florida dairy farms demonstrated that Terminator traps collected significantly more (13,323/trap) house flies (Musca domestica L.) than the others tested. Final Flight, Fly Magnet, and FliesBeGone traps collected intermediate numbers of flies (834-2,166), and relatively few were caught with ISCA, Advantage, Fermone Big Boy, Squeeze & Snap, or OakStump traps (<300). Terminator traps collected about twice as many flies (799.8/trap) as FliesBeGone traps (343.8) when each trap was baited with its respective attractant, but when the attractants were switched between the two trap types, collections were significantly lower (77-108) than was observed with traps baited with their respective attractant. Solutions of molasses were significantly more attractive to house flies than honey, maple syrup, or jaggery (date palm sugar). Field-expedient traps constructed from discarded PET water bottles were much less effective than commercial traps, but painting the tops of such traps with black spray paint resulted in a six-fold increase in trap capture.

The partitioning of assimilates in fruits, which are economically important sink organs, is ruled by different physiological processes and affected by both environmental and agronomical factors. The bulk of the water and solutes, required for growth, is imported into fruits and seeds through xylem and phloem. In the stone fruits, five vascular bundles enter the base of the fruit, then dividing to supply either the flesh or the seed. The main sugars accumulated in stone fruits include fructose, glucose, and sucrose, along with other minor saccharides. The mechanisms of phloem loading in these fruit species have not been fully elucidated yet, but the available data hint either an apoplastic or a symplastic type or possibly a combination of both, depending on the species and the sugar considered. Similarly, phloem unloading mechanisms, elucidated for a small number of species, depend on genotype and developmental stage. Remarkably, key enzymes and transporters involved in the main sugars-conversion and transport pathways have received considerable attention. In stone fruit trees, the presence of an elevated number of fruits alters the source-sink balance, with a consequent intensification of competition among them and between vegetative and reproductive growth. The main environmental factors affecting this balance and the agronomical/artificial manipulations of source-sink relationships to achieve adequate fruit production and quality are reviewed.