Morphology, Physiology and Analysis Techniques of Grapevine Bud Fruitfulness: A Review

Grapevine reproductive development extends over two growing seasons (vegetative cycles), for the complete formation of inflorescences and clusters. Induction and floral differentiation, the mechanism that leads to the formation of reproductive structures inside dormant buds, is a complex process divided into three well-defined stages (formation of anlagen, inflorescence primordia and flowers). This sequence of stages comprises morphological, biochemical, and physiological events, influenced by a set of environmental and endogenous factors. Inflorescence primordia formation determines the potential number of clusters that will be formed in the following growing season. Thus, during bud dormancy, viticulturists and winemakers can obtain a first yield prediction through the determination of bud fruitfulness. This information allows adjustments to be made to bud load, promoting balanced yield and fruit quality and higher commercial value. The present review describes the morphology and physiology of the formation of inflorescence primordia, as well as discusses the main abiotic and biotic factors involved, including a physiological disorder known as primary bud necrosis. In the same way, we intend to approach the more used techniques of analysis of fruitfulness and its importance for a robust yield forecasting.

Effect of Trinexapac-ethyl associated with nitrogen fertilization on upland rice nutritional status and grain yield

Trinexapac-ethyl spraying time and proper nitrogen rate are essential to reduce plant height and lodging at harvest, without affecting rice yield and nutritional balance. This study aimed to evaluate trinexapac-ethyl spraying time and N contents as topdressing for upland rice paddies. The experiment was carried out in a randomized block design and a 4x5 factorial scheme, with four replications. Treatments consisted of four trinexapac-ethyl spraying times, in the phenological stages of tillering, floral differentiation, between tillering and floral differentiation, and a control (without spraying), and five nitrogen rates (0, 50, 100, 150, and 200, kg ha-1) as topdressing. As nitrogen topdressing rates increased, leaf contents of N, Fe++, and Zn++ increased, while S and Mn++ decreased; however, contents of P, Ca++, Mg++, B, and Cu++ were little influenced. When trinexapac-ethyl was applied, leaf contents of N, P, S, B, and Zn++ were little influenced, while P, Ca++, Mg++, Fe++, and Mn++ increased, and Cu++ decreased. Trinexapac-ethyl can be applied at tillering without decreasing rice yield. Upland rice increased grain yield by 58 and 46% in two consecutive crop years due to application of about 120 kg N ha-1 as topdressing.

Estimation of physiological parameters on high density plantations and population arrangements of Musa AAA Simmonds

In Uraba, Antioquia (Colombia), there is a shortage of first-semester fruits and a surplus of second-semester fruits as a result of low or high precipitation, respectively, affecting the value of production. An experiment was established during 2015-2016 in an area representative of the region in order to determine the field distribution and plantation density that maximize the agronomic potential of Musa AAA Simmonds cv. Williams. The population arrangement treatments (rectangle, triangle and double row), planting densities (2,000; 2,500, 3,000 and 3,500 plants/ha) and one control (1,700 plants/ha in a triangle) were evaluated in a complete, random block design with three repetitions. In the phenological phases of floral differentiation, flowering and harvest, the gas exchange was quantified with measurements of the photosynthesis rate, internal CO2 concentration, stomatal conductance, transpiration, vapor pressure deficit, and water use efficiency. The leaf temperature, quantum photosynthesis efficiency and efficient use of radiation were also considered. The yield components and fruit quality were estimated with fruit mass, number of hands, number of fruits, length of the last hand and degree of the second and last hand. The results showed that the density 2,500 plants/ha, distributed in a triangle or double row, promoted the best use of the climate elements associated with photosynthetic activity under the environmental conditions of Uraba, Antioquia.

Different Summer and Autumn Water Deficit Affect the Floral Differentiation and Flower Bud Growth in Apricot (Prunus armeniaca L.)

In deciduous fruit species, floral bud initiation, differentiation and organogenesis take place during the summer–autumn season that precedes anthesis. Among factors able to modify the regularity of these processes, water availability represents a crucial aspect. This investigation aimed to assess the influence of different summer and autumn water deficit and re-watering treatments on floral morphogenesis, xylem vessel differentiation and quality of flower buds. Trials were carried out on two-year-old potted apricot trees (cv. ‘Portici’) which were submitted to different regimes: (i) fully irrigated plants; (ii) stressed plants in June (S1), July (S2) and October (S3) followed to re-watering. Midday stem water potential was used to determine water status, and leaf gas exchanges were measured during trials. Histological analyses on floral differentiation, xylem progression within flower buds and biological observations were carried out. Both summer water stress periods affected the floral differentiation leading to a temporary shutdown. The S1 trees were able to recover the development of meristematic apices while S2 had a strong delay. All drought treatments caused a slower xylem progression, variations in bud size, blooming entity and flower anomalies. Results particularly highlights the importance of water availability also in early autumn.

Influence of Regulated Deficit Irrigation and Environmental Conditions on Reproductive Response of Sweet Cherry Trees

The reproductive response of fifteen year old sweet cherry trees (Prunus avium L.) combination ‘Prime Giant’/SL64 under Mediterranean climate to deficit irrigation was studied in a commercial orchard in south-eastern Spain for four seasons. Three irrigation treatments were assayed: (i) control treatment, irrigated without restrictions at 110% of seasonal crop evapotranspiration; (ii) sustained deficit irrigation treatment, irrigated at 85% ETc during pre-harvest and post-harvest periods, and at 100% ETc during floral differentiation, and (iii) regulated deficit irrigation treatment, irrigated at 100% ETc during pre-harvest and floral differentiation and at 55% ETc during post-harvest. The duration and intensity of the phenological phases of sweet cherry trees, including cold accumulation, flowering, fruit set or fruit and vegetative growth, were assessed to ascertain whether the different irrigation strategies imposed affect the trees’ reproductive response (fruit yield, fruit size, leaf area, fruit physiological disturbances, and starch and soluble carbohydrates stock) in the same season or have a negative effect in the next season. Deficit irrigation did not advance, enhance or penalize flowering, fruit set or fruit growth. Neither did it diminish carbohydrate concentration in roots or cause an increase in the number of double fruits, which was more linked to high temperatures after harvest. However, deficit irrigation decreased vegetative growth and consequently the leaf area/fruit ratio, which, when it fell below 180 cm2 fruit−1, affected cherry size.

Can the Nitrogen and Silicon Increase the Productivity and Yield in Rice Crops in the Rainfed Environment?

There is much doubt as to whether, in fact, the combination of nitrogen and silicate fertilization can increase yield and post-harvest yield in rainfed rice. The objective of this study was to investigate the effect of silicate and nitrogen fertilization on the development, quality, yield and post-harvest yield of rice cultivated in the rainfed environment. A field experiment was carried out in the 2014/2015 harvest in a 4 × 4 randomized block design with four replications. The first factor corresponded to the nitrogen doses (0; 50; 100 and 200 kg ha-1 of N), in the form of urea, and the second factor at silicon doses (0; 7.5; 15 and 30 kg ha-1 Si), in the form of calcium silicate. Si affected the chlorophyll content at 45 days after sowing (DAS) suggesting being important in floral differentiation. The increase in N doses caused higher levels of chlorophyll in rice leaves at 55, 65 and 85 DAS, regardless of whether they supplied Si. Plant height, number of tillers, weight of one thousand seeds, total grain yield and of whole grains were not influenced by the Si supply. However, Si doses reduced the yield of broken grains, thus reducing postharvest losses and, consequently, improving grain quality in the beneficiation process.

The Dynamics of Cytokinin Changes after Grafting of Vegetative Apices on Flowering Rapeseed Plants

Despite numerous studies, the role of hormones in the induction of shoot apical meristem leading to reproductive development, especially regarding thermoperiodic plants, is still not fully understood. The key problem is separating the effects of the low temperature required for vernalization from those responsible for low temperature stress. An earlier experiment demonstrated the correlation between an increase of cytokinin level in the apical parts of winter rapeseed and the transition time into their reproductive phase during vernalization, i.e., low temperature treatment. From data obtained from the presented experiments, this study aims to contribute to the understanding the role of cytokinins in the induction of flowering based on the grafting of vegetative apical parts of winter rapeseed (scion) on the reproductive (stock) winter and spring genotypes. On the basis of analyses carried out using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry in combination with microscopic observation of changes at the apical meristem, it was indicated that the increase in the amount of trans-zeatin and trans- and cis-zeatin-O-glucoside derivatives appeared in the early stages of apex floral differentiation. During further development, the content of all investigated cytokinins passed through the maximum level followed by their decrease. The final level in reproductive apices was found to be higher than that in vegetative ones.

Identification of Nitric Oxide Responsive Genes in the Rudimentary Leaves of Litchi chinensis

Litchi (Litchi chinensis Sonn.) is an evergreen woody fruit tree widely cultivated in subtropical and tropical regions. Warm winter and hot spring often leads to abnormal floral differentiation in litchi. Under this condition, the rudimentary leaves in the floral buds expand and the inflorescences will stop developing. Thus, how to promote abortion of rudimentary leaves in litchi inflorescence are important for floral development. Previous study indicated that nitric oxide (NO) produced by sodium nitroprusside (SNP) promoted flowering and abortion of rudimentary leaves in litchi. In the present study, a suppression subtractive hybridization (SSH) was used to identify NO responsive genes. As a result, 16 high homologous ESTs were obtained from the SSH library of the SNP treated rudimentary leaves. The ESTs were classified into three groups. They are disease/defensive, protein destination and storage, and protein synthesis. Quantitative reverse transcription PCR (qRT-PCR) analysis indicated that 6 out of the 7 randomly selected ESTs’expression showed an increasing trend from 0 h to 10 h of SNP treatment. It is suggested that the litchi homologs 18S ribosomal RNA gene, cytochrome P450 like TBP, and the senescence-associated protein, chaperone protein, and a hypothetical protein encoding genes may be involved in the NO-induced senescence in litchi rudimentary leaves. LcERD15-like may be a key gene involved in this process.