Analysis of the Variability of Floral and Pollen Traits in Apple Cultivars—Selecting Suitable Pollen Donors for Cider Apple Orchards

Most apple trees (Malus domestica Borkh.) are self-incompatible and fruit yield depends on cross-pollination between genetically compatible cultivars with synchronous flowering. Flowering intensity can vary strongly among years due to the biennial bearing habit of the cultivars. The knowledge of the phenological stages and floral and pollen characteristics is essential to select suitable pollen donors. We evaluated the phenotypic variability of flowering-related traits (i.e., flowering phenology, flowering intensity, pollen production and pollen quality) in 45 apple cultivars over two successive flowering seasons. Large phenotypic variability was found among the studied cultivars indicating that the local germplasm collection provides a good source of genetic and phenotypic diversity. However, low correlations were observed between floral biology traits and, consequently, the improvement in one trait seems not to affect other traits. Some of the cultivars such as ‘Perurico’ and ‘Raxila Dulce’ regularly produced copious amounts of high-quality pollen which can improve the pollen load dispersion leading to a most effective pollination process. We did not identify statistically significant correlations between pollen attributes and the biennial bearing phenomenon. The large variation in bloom dates from year-to-year observed under a typical Oceanic climate makes it advisable to combine cultivars in new plantings.

The HADES Yield Prediction System – A Case Study on the Turkish Hazelnut Sector

Crop yield forecasting activities are essential to support decision making of farmers, private companies and public entities. While standard systems use georeferenced agro-climatic data as input to process-based simulation models, new trends entail the application of machine learning for yield prediction. In this paper we present HADES (HAzelnut yielD forEcaSt), a hazelnut yield prediction system, in which process-based modeling and machine learning techniques are hybridized and applied in Turkey. Official yields in the top hazelnut producing municipalities in 2004–2019 are used as reference data, whereas ground observations of phenology and weather data represent the main HADES inputs. A statistical analysis allows inferring the occurrence and magnitude of biennial bearing in official yields and is used to aid the calibration of a process-based hazelnut simulation model. Then, a Random Forest algorithm is deployed in regression mode using the outputs of the process-based model as predictors, together with information on hazelnut varieties, the presence of alternate bearing in the yield series, and agro-meteorological indicators. HADES predictive ability in calibration and validation was balanced, with relative root mean square error below 20%, and R2 and Nash-Sutcliffe modeling efficiency above 0.7 considering all municipalities together. HADES paves the way for a next-generation yield prediction system, to deliver timely and robust information and enhance the sustainability of the hazelnut sector across the globe.

PENGARUH PEMBERIAN PAKLOBUTRAZOL DAN PUPUK TERHADAP INDUKSI PEMBUNGAAN MANGGIS (Garcinia mangostana L.)

Manggis (Garcinia mangostana L.) merupakan buah tropis dan termasuk komoditas ekspor unggulan. Produksi manggis di Indonesia masih tergolong rendah dan tidak kontinu, karena beberapa faktor yang mempengaruhinya, salah satunya yaitu sifat pembungaan dan pembuahan manggis yang bersifat biennial bearing. Oleh karena itu perlu dilakukan upaya untuk menginduksi pembungaan manggis di luar musim. Penelitian ini bertujuan untuk mendapatkan teknologi yang efektif untuk induksi pembungaan manggis dengan pengunaan paklobutrazol dan pupuk. Penelitian ini dilaksanakan di Desa Mulangmaya, Kecamatan Kota Agung Timur, Kabupaten Tanggamus pada ketinggian 250 mdpl dari bulan September 2018 hingga April 2019. Penelitian ini menggunakan Rancangan Acak Kelompok (RAK) dengan faktor tunggal yang terdiri dari 3 perlakuan yaitu: (K0) tanpa perlakuan, (K1) NPK Mutiara 1 kg/tanaman, paklobutrazol 2000 ppm, KNOӡ 20 g/l, dan (K2) pupuk kandang sapi 10 kg/tanaman, NPK Mutiara 1 kg/tanaman, paklobutrazol 2000 ppm, KNOӡ 20 g/l. Data yang diperoleh dianalisis dengan analisis ragam dan dilakukan pemisahan nilai tengah dengan uji orthogonal kontras pada taraf nyata 5%. Hasil penelitian menunjukkan bahwa perlakuan paklobutrazol dan pupuk dapat menginduksi pembungaan manggis dibandingkan dengan tanpa perlakuan. Penambahan pupuk kandang sapi 10 kg/tanaman, NPK 1 kg/tanaman dengan pemberian paklobutrazol 2000 ppm dan KNOӡ 20 g/l lebih berpotensi mempercepat pembungaan manggis dengan selisih (5,80 %) dan meningkatkan jumlah buah per cabang sampel tertinggi dengan selisih (39,13 %) jika dibandingkan tanpa penambahan pupuk kandang.

Toward Systematic Understanding of Flower Bud Induction in Apple: A Multi-Omics Approach

The induction of flower buds in apple (Malus × domestica Borkh.) is tightly connected to biennial bearing, which is characterized by alternating years with high (ON) and low or no (OFF) crop loads. In order to study this irregular cropping behavior, spur buds from ON- and OFF-trees of the biennial-bearing cultivar ‘Fuji’ and the regular bearing cultivar ‘Gala’ were collected. First, the time of flower bud initiation was precisely determined for both cultivars by histological analysis. Moreover, for a systematic understanding of flower bud induction in apple, the physiological and molecular mechanisms within the bud tissue were evaluated over four weeks prior to flower bud initiation by employing a multi-omics approach, including RNA sequencing, proteomic and metabolic profiling. Gene and protein enrichment analysis detected physiological pathways promoting and inhibiting early flower bud development. Metabolic profiles from the cropping treatments revealed a greater abundance of thiamine, chlorogenic acid, and an adenine derivative in spur buds from OFF-trees, whereas tryptophan was more abundant in the buds collected from ON-trees. Cultivar comparison indicated that chlorogenic acid was more abundant in ‘Gala’ than in ‘Fuji’ spur buds, whereas the opposite effect was found for tryptophan. Genes controlling tryptophan biosynthesis were not affected by ON- and OFF-treatments, but genes assigned to the metabolism of tryptophan into indoleacetate were differentially expressed between cultivars and treatments. The multi-omics approach permitted analyzing complex plant metabolic processes involved in early flower bud development and more specifically presumably in flower bud induction by tracing some pathways from gene to product level.

Plant Growth Regulators in Flowering Alternation of the Fuji Suprema Apple Tree

Aims: Research on alternate bearing in apple trees is usually focused on chemical thinning techniques, but in recent decades synthetic bioregulators have proven to be effective in promoting or inhibiting floral induction in apple trees. However, the results can be variable since some cultivars are prone to alternation, as Fuji and its clones. The objective of the present study was to observe the effect of naphthalene acetic acid (NAA), Ethephon, and their combinations in the formation of flowering buds avoiding flowering alternation, in Cv, Fuji Suprema. Place and Duration of Study: The experiments were carried out in southern Brazil, municipality of Caçador / SC, during the cycles from 2014 to 2019, in the cultivar Fuji Suprema / Marubakaido / M9, with 12 years old. Methodology: Several variables were evaluated such as flowering return, fruit set, yield, number of fruits per plant, average fresh fruit mass, and biennial bearing index (BBI). Results: The results were variable and showed that NAA and Ethephon had little effect on reducing flowering alternation when applied during the vegetative phase of the Fuji Suprema apple tree. After years of high productivity, there was a decrease in the yield, even in the treatments of NAA and Ethephon. Ethephon or its combination with NAA has a thinning effect, but without influence on the return of flowering.

BREEDING OF NEW PEAR WINTER CULTIVAR 'PANDORA'

Psylla and fire blight resistance combined with fruit quality are still pearbreeding aims at Research Institute for Fruit Growing (RIFG) Pitești, Romania. The new pear cultivar 'Pandora' was registered in 2019, being released by interspecific hybridization between 'Euras' cv. [(PyrusserotinaxOlivier de Serres) x Doyenne d'hiver] and 'Tse Li' cv. (P.ussuriensis). The trees are medium vigor, weak branching and semi-upright habit being productive and with low tendency to biennial bearing. The fruit ripens 10-15 days earlier than 'Euras', at end of September.Fruit weight is about 250g, flesh is yellowish white, fine, crisp, juicy, sweetand flavored. The skin color changes from green to yellow upon maturity. It is highly resistant to fire blight and pear psylla under the standard spraying program. Therefore, this new cultivar shows a good potential for commercial fruit growing.

PENGARUH PENGGUNAAN PACLOBUTRAZOL, KNO3 DAN ETEFON PADA PEMACUAN PEMBUNGAAN TANAMAN MANGGIS (Garcinia mangostana L.)

Mangosteen (Garcinia mangostana L.) is a tropical plant that bears seasonal fruit and is one of Indonesia's leading export commodity. Mangosteen production in Indonesia is still low and not continuous, because there are several factors that influence it. One of them is the character of biennial bearing in mangosteen one year produce high fruit load followed by a next year of very low production. Therefore it is necessary to induce off season mangosteen flowering. This study aims to determine: (1) the effect of Paklobutrazol on the flowering of mangosteen plants, (2) the effect of adding KNO3 and Etefon on the acceleration of mangosteen flowering. This research was conducted in Mulangmaya Village, Kota Agung Timur District, Tanggamus, Lampung. Regency at an altitude of 250 m above sea level from September 2018 to April 2019. This research used a Randomized Block Design (RBD) with a single factor consisting of 3 treatments, namely P1 ( manure 10 kg/plant + NPK Nitrophonska 1 kg/plant, P2 (Paclobutrazol 2 ml/l + KNO3 20 g/l + manure 10 kg/plant + NPK Nitrophonska 1 kg/plant), and P3 (Paclobutrazol 2 ml/l + Etefon 40 ml/l + manure 10 kg/plant + NPK Nitrophonska 1 kg/plant). The data obtained were analyzed by analysis of variance and the mean separation was carried out by orthogonal contrast test at the 5% significance level. The results showed that the treatment of P2 (Paclobutrazol 2 ml/l + KNO3 20 g/l + manure 10 kg/plant + NPK Nitrophonska 1 kg/plant) on mangosteen plants was able to spur flowering faster with a difference of 12 days (8.70% ), and increased the total number of fruits per plant by a difference of 41 fruit (38.80%). The P3 treatment (Paclobutrazol 2 ml/l + Etefon 40 ml/l + manure 10 kg/plant + NPK Nitrophonska 1 kg/plant), unexpectedly causing significant leaf drop 3 days after Ethephon spray, and new leaves were formed a month later. Keywords : Ethephon, KNO3, Paclobutrazol, and mangosteen flowering

Differential expression of genes in olive leaves and buds of ON- versus OFF-crop trees

Alternate bearing (AB) refers to the tendency of trees to have an irregular crop load from 1 year (ON) to the next year (OFF). Despite its economic importance, it is not fully understood how gene networks and their related metabolic pathways may influence the irregular bearing in olive trees. To unravel molecular mechanisms of this phenomenon in olive (cv. Conservalia), the whole transcriptome of leaves and buds from ON and OFF-trees was sequenced using Illumina next generation sequencing approach. The results indicated that expressed transcripts were involved in metabolism of carbohydrates, polyamins, phytohormones and polyphenol oxidase (POD) related to antioxidant system. Expression of POD was increased in leaf samples of ON- versus OFF-trees. The expression pattern of the greater number of genes was changed more in buds than in leaves. Up-regulation of gene homologues to the majority of enzymes that were involved in photorespiration metabolism pathway in buds of ON-trees was remarkable that may support the hypotheses of an increase in photorespiratory metabolism in these samples. The results indicated changes in expression pattern of homologous to those taking part of abscisic acid and cytokinin synthesis which are connected to photorespiration. Our data did not confirm expression of homologue (s) to those of chlorogenic acid metabolism, which has been addressed earlier that have a probable role in biennial bearing in olive. Current findings provide new candidate genes for further functional analysis, gene cloning and exploring of molecular basses of AB in olive.