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Steady-state nutrient management is essential in hydroponic culture. Determination of an appropriate refill solution is attained using the principle of mass balance. Optimizing the ratio of nutrient elements and refill solution concentrations requires an understanding of the ratio of nutrients in tissue to water, which is measured as water use efficiency (WUE). This ratio is then multiplied by the desired concentration of nutrients in leaf tissue to determine the refill solution composition. Deep-flow hydroponics enables constant monitoring of solution parameters and root health. We have achieved a steady-state nitrogen concentration in solution by using an automated pH control system that adds a solution of 50 mM nitric acid and 200 mM ammonium sulfate. The pH remains stable throughout the life cycle as roots release a similar ratio of protons and hydroxide ions to balance uptake of either ammonium or nitrate. Daily monitoring of electrical conductivity (EC) guides adjustment of the refill solution concentration. A variable WUE and water to nutrient uptake ratio among species necessitates custom refill solutions. In our preliminary studies, wheat (Triticum aestivum) has a moderate WUE (3 g L-1) but ceases substantial nutrient uptake late in the lifecycle and the EC thus increases over time, causing nutrient accumulation in solution. Lettuce (Lactuca sativa) also has a moderate WUE (3 g L-1), and the EC of the solution remains stable. Tomato (Solanum lycopersicum) has a high WUE (6 g L-1), causing reduced EC and nutrient solution depletion. Monitoring solution compositions has allowed us to optimize the refill solution and acid addition concentration among species and lifecycle stages.

Plant breeding for increased crop water use efficiency or drought stress resistance requires methods to quickly assess the transpiration rate (E) and stomatal conductance (gs) of a large number of individual plants. Several methods to measure E and gs exist, each of which has its own drawbacks and shortcomings. To add to this toolbox, we developed a method that uses whole-plant thermal imaging in a controlled environment, where aerial humidity is changed rapidly to induce changes in E that are reflected in changes in leaf temperature. This approach is based on a simplified energy balance equation, without the need for a reference material or complicated calculations. To test this concept, we built a double-sided, perforated, open-top plexiglass chamber that was supplied with air at a high flow rate (35 L min− 1) and whose relative humidity (RH) could be switched rapidly. Measurements included air and leaf temperature as well as RH. Using several well-watered and drought stressed genotypes of Arabidopsis thaliana that were exposed to multiple cycles in RH (30 to 50% and back), we showed that leaf temperature as measured in our system correlated well with E and gs measured in a commercial gas exchange system. Our results demonstrate that, at least within a given species, the differences in leaf temperature under several RH can be used as a proxy for E and gs. Given that this method is fairly quick, noninvasive and remote, we envision that it could be upscaled for work within rapid plant phenotyping systems.

Maize (Zea mays L.) is a multipurpose crop useful in human diet and animal feed. Maize yield improvement has continued to receive a lot of research attention, but less so for plant morphological characteristics especially considering the ongoing climate change impacts that have affected the response of many crops to the environment. The information that can be received from research on morphological traits could be critical, as it could enhance the efforts at ensuring proper crop adaptation to climate change, in addition to the direct or indirect contribution to grain yield. Five maize varieties were planted in randomized complete block design experiments and monitored in 8 environments at the Obafemi Awolowo University Teaching and Research Farm to examine the response of maize morphology to environments, seasons and weather factors. Result showed highly significant effect of environment on most measured traits (P ≤ 0.01) with significantly higher means in the early season. Beyond the seedling stage, morphological traits responded positively to soil moisture, relative humidity, and solar radiation, On the contrary, soil heat flux, temperature, and heat unit negatively affected maize seedling growth. Keywords: Climate change, crop phenology, crop physiology, growth analysis, seedling emergence and vigour. Title: Response of some morphological characteristics of maize (Zea mays L.) to environment, season and weather factors in a tropical rainforest location Author: C. A. FAYOSE, M. A. B. FAKOREDE, A. OLUWARANTI International Journal of Recent Research in Life Sciences (IJRRLS) ISSN 2349-7823 Vol. 9, Issue 2, April 2022 - June 2022 Page No: 71-78 Paper Publications Website: www.paperpublications.org Published Date: 23-May-2022 DOI: https://doi.org/10.5281/zenodo.6573560 Paper Download Link (Source): https://www.paperpublications.org/upload/book/Response%20of%20some%20morphological-23052022-7.pdf, International Journal of Recent Research in Life Sciences (IJRRLS), ISSN 2349-7823, Paper Publications, Website: www.paperpublications.org, {"references":["[1]\tAjayo, B. S., Badu-Apraku, B., Fakorede M. A. B. & Akinwale, R. O. (2021). Plant density and nitrogen response of maize hybrids in diverse agroecologies of West and Central Africa. Aims Agriculture and Food, 6 (1), 381 – 400.","[2]\tBakht, J., Shafi, M., Rehmam, H., Uddin, R. & Anwar, S., (2011). Effect of planting methods on growth, phenology and yield of maize varieties.Pakistan Journal of Botany, 43(3):1629-1633.","[3]\tFakorede, M.A.B. (1985). Response of maize to planting dates in a tropical rainforest location. Experimental Agriculture, 21, 19-30.","[4]\tFakorede, M.A.B. & Agbana, S.B. (1983). Heterotic effects and association of seedling vigor with mature plant characteristics and grain yield in some tropical maize cultivars. Maydica, 28, 327-338.","[5]\tFakorede, M. A. B. & Akinyemiju, O. A. (2003). Climate change: effects on maize production in a tropical rainforest location. P. 272-282. In Badu-Apraku, B., Fakorede, M. A. B., Ouedraogo, M., Carsky, R.J. and Menkir, A. (Eds.). Maize revolution in West and Central Afica. Proceedings of a Regional Maize Workshop, IITA-Cotonou, Benin Republic. 14-18 May 2001. WECAMAN/IITA.","[6]\tFayose, C.A. & Fakorede M.A.B. (2014). Growth analysis of maize varieties at the seedling and vegetative developmental stages. Proceedings of the Genetics Society of Nigeria Conference, Rubber Research Institute, Benin, Edo State, Nigeria, October 20-24. pp 425-429.","[7]\tFayose, C. A., Fakorede, M. A. B., Badu-Apraku, B. and Abebe, M. (2022). Canopy architecture and grain yield of maize in the rainforest of Southwestern Nigeria. Manuscript submitted to Field Crop Research.","[8]\tFayose, C. A. & Fakorede M. A. B. (2021). Planting date effects on maize (Zea mays L.) growth and development in the rainforest of southwestern Nigeria. Acta Agriculturae Slovenica, 117 (1), 101 -109.","[9]\tFuksa, P., hakl, J. Kocourkova, D. & Vesala, M. (2004). Influence of weed infestation on morphological parameters of maize. Plant Soil Environment, 50(8), 371 – 378.","[10]\tJibrin M. J., Kamara, A.Y. & Ekeleme, F. (2012). Simulating planting date and cultivar effects on dryland maize production using CERES-maize model. African Journal of Agricultural Research, 7(40), 5530-5536","[11]\tLi, C., Li, Y., Shi, Y., Song, Y., Zhang, D., Buckler, E. S., Zhang, Z., Wang, T. & Li, Y. (2015). Genetic control of the leaf angle and leaf orientation value as revealed by ultra-high density maps in three connected maize populations. PLOS One Journal 10(3): e0121624.","[12]\tOluwaranti, A., Fakorede, M.A.B. & Badu-Apraku, B. (2008). Grain yield of maize varieties at different maturity groups under marginal rainfall conditions. Journal of Agricultural Sciences, 58(8), 183 - 191.","[13]\tPioneer, (2016). Corn leaf architecture response to plant density. Pioneer® GrowingPoint® \tAgronomy.Published online at https://www.pioneer.co m/home/site/mobile/pioneer growingpoint_agronomy/corn_leaf_architecture/","[14]\tRomdhane, L., Dal, C. C., Vamerali, T & Radhouane L. (2016). Effect of drought and salinity o maize phenology, morphology and productivity in a semi-arid environment. Italian Journal of Agrometeorology, 3, 43 – 54.","[15]\tSAS Institute Inc. (2000). \"Base SAS® 9.0 Procedures Guide.\" Cary, NC: SAS Institute Inc.","[16]\tSong, L., Jin, J. & He, J. (2019). Effect of severe water stress on maize growth process in the field. Sustainability, 11, 1-18."]}

C4 crops of agricultural importance all belong to the NADP-malic enzyme (ME) subtype, and this subtype has been the template for C4 introductions into C3 crops, like rice, to improve their productivity. However, the ATP cost for the C4 cycle in both NADP-ME and NAD-ME subtypes accounts for > 40% of the total ATP requirement for CO2 assimilation. These high ATP costs, and the associated need for intense cyclic electron transport and low intrinsic quantum yield Φ CO 2 , are major constraints in realizing strong improvements of canopy photosynthesis and crop productivity. Based on mathematical modelling, we propose a C4 ideotype that utilizes low chloroplastic ATP requirements present in the nondomesticated phosphoenolpyruvate carboxykinase (PEP-CK) subtype. The ideotype is a mixed form of NAD(P)-ME and PEP-CK types, requires no cyclic electron transport under low irradiances, and its theoretical Φ CO 2 is c. 25% higher than that of a C4 crop type. Its cell-type-specific ATP and NADPH requirements can be fulfilled by local energy production. The ideotype is projected to have c. 10% yield advantage over NADP-ME-type crops and > 50% advantage over C3 counterparts. The ideotype provides a unique (theoretical) case where Φ CO 2 could be improved, thereby paving a new avenue for improving photosynthesis in both C3 and C4 crops.

The present investigation was carried out at green house, department of crop physiology, S.V Agricultural College, Tirupati to know the effect of seed priming on growth and physiological parameters of dry direct sown rice (Oryza sativa L.) under pot culture. The experiment was conducted in completely randomized design with 20 combinations (4 varieties and 5 treatments). Varieties screened are MTU 1010, JGL 20171, NLR33671 and MTU 1112, whereas treatments are Control (Hydropriming/Water soaking), 1000 PPM GA3 and combination of both gibberillic acid and KNO3 treatments i.e.; GA3 (200PPM, 500PPM, 1000PPM + KNO3@3%), in order to know the effect of growth and physiological performance of seed primed rice genotypes under pot culture. Various physiological observations like plant height, No of leaves, Leaf area, Total dry matter, Days to 50% flowering and Yield attributes was measured in all four genotypes.

Traditional leafy vegetables provide affordable sources of micronutrients to many people in Zimbabwe. They are produced by smallholder farmers with limited knowledge on the agronomic value of high-quality seed and the seed is rarely tested to determine its quality. This study was therefore conducted to evaluate the germination of seeds of three traditional leafy vegetables sourced from five different farmers and the morphological characteristics of the seedlings. The seeds were collected in the growing season of 2015 to 2016, stored at room temperature and tested for germination in the laboratory at regular monthly intervals during storage. Field germination tests were conducted only once. The seeds tested were classified as normal seedlings, abnormal seedlings, fresh non-germinated seeds or dead seeds. Morphological analysis was conducted at seedling stage, including seven qualitative characters and one quantitative character. Mean separation based on the least significance difference at 5% indicated that percentage germination, purity and 1000-seeds weight for all three species significantly differed among sources. The results showed that Cleome gynandra had lowest germination percentages, Amaranthus hybridus was intermediate and Bidens pilosa had highest values throughout the tests. C. gynandra seed exhibited dormancy, showing high levels of fresh non-germinated seed percentage after each test, which is potentially disastrous for the farmers. The combination of pre-chilling, light, potassium nitrate and alternating temperatures as a way of improving germination for C. gynandra needs further validation.

A novel cropping system for potato was tested for two consecutive years under normal Dutch agronomic conditions. Seedlings from two experimental genotypes of hybrid true potato seeds were produced in a greenhouse nursery and transplanted into the field 5 weeks after sowing to assess tuber yield levels and to study effects of hilling on tuber yield and number, tuber size distribution and tuber greening. Field experiments had a split-plot design with hilling treatments as the main plots and genotypes as the sub-plots. Final harvest was at 122 and 132 days after transplanting in 2017 and 2018, respectively. Hybrid seedlings were transplanted into small initial ridges and irrigated straight after planting. Three hilling treatments were applied between transplanting and 100% canopy cover. Treatment ‘zero hilling’ did not receive any additional hilling after transplanting. Treatments ‘double hilling’ and ‘triple hilling’ received two and three additional hilling treatments, respectively. Total tuber yields at final harvest in both years were not affected by the hilling treatments. Yields for the respective genotypes were 26 and 30 Mg/ha in 2017 and 25 and 32 Mg/ha in 2018. Total tuber numbers were only affected by hilling treatments in 2017, where under hilled conditions, plants produced more tubers compared with plants under zero hilling. Plants under zero hilling yielded more tubers in size class > 40 mm compared with triple hilling in 2017. In 2018, no significant effects of hilling on tuber numbers were found, but the trend was similar to that in 2017.

Dominant species in intercropping experience less resource competition compared with its monoculture. This reduced competition for resources may allow cultivating the dominant species at an increased density in intercropping to obtain greater yield. However, experimental results are inconclusive when the optimal within row density in the sole crop is not well established. Here, we conducted a two‐year experiment to test the hypothesis that optimal within row plant density of dominant species in intercropping would be higher in the intercrop than in the sole crop. We tested three maize densities (3, 4.5, and 6 plants m−1) in both sole maize and two replacement designed intercrops. The row configurations of two intercrops are two rows maize intercropped with four rows peanut (M2P4) and four rows maize intercropped with four rows peanut (M4P4). Peanut was grown at the same plant density of 12 plants m−1 row in both sole crop and intercrops. The results indicated that increasing maize density from the optimal density in monoculture is not worthy of promotion to improve yield in intercropping, which denied our hypothesis. The land equivalent ratios (LER) in the dry year (2017) were higher than the wet year (2016). Maize yields per unit area of the whole intercropping system were highest with densities of 4.5 and 6 plants m−1 row, with no significant difference between these two densities. Maximum maize yields in sole cropping were obtained with maize densities of 6 plants m−1 row. Intercropping provided higher yields at low and intermediate sole crop maize densities, but not at high sole crop maize density. Average land equivalent ratios at 3, 4.5, and 6 plants m−1 of maize were 1.09, 1.04, and 0.95 in 2016, and 1.07, 1.10, and 1.02 in 2017. Our results suggest that intercropping performs better at conditions with less resources than adequate resources.

Purpose of Review The world-wide demand for agricultural products is rapidly growing. However, despite the growing population, labor shortage becomes a limiting factor for agricultural production. Further automation of agriculture is an important solution to tackle these challenges. Recent Findings Selective harvesting of high-value crops, such as apples, tomatoes, and broccoli, is currently mainly performed by humans, rendering it one of the most labor-intensive and expensive agricultural tasks. This explains the large interest in the development of selective harvesting robots. Selective harvesting, however, is a challenging task for a robot, due to the high levels of variation and incomplete information, as well as safety. Summary This review paper provides an overview of the state of the art in selective harvesting robotics in three different production systems; greenhouse, orchard, and open field. The limitations of current systems are discussed, and future research directions are proposed.

The recent invention of hybrid breeding technology for potato has led to an increased interest in hybrid potato R&D. Hybrid true potato seeds (TPS) are used to produce planting materials such as transplants and seedling tubers, but can also be used for direct seeding of seed or ware crops. Transplants and seedling tubers can be used to produce seed tubers or ware tubers. The rise in R&D in hybrid breeding creates the need for phenological scales of growth and development of plants produced by the various planting material types of hybrid-TPS. The BBCH (Biologische Bundesanstalt, Bundessortenamt and CHemical Industry) scale is one of the phenological scales developed for the description of the growth and development stages of plants. In 1993, a BBCH scale with descriptions for potato plants was released. The original BBCH scale gave standardised descriptions for TPS- and tuber-grown plants. Differences in the morphology of plants originating from the different planting materials in terms of types of branches and differences in below-ground growth and development were not included. Moreover, for reproductive growth stages, crucial for hybrid breeding, the original scale is incomplete as it does not carefully take the complex sympodial branching into account. Methods of describing growth of tubers and berries are complex and impossible to use when final tuber mass or berry size is unknown. The current paper augments the original BBCH scale, while retaining its structure and logic. It provides alternative and comprehensive descriptions of growth stages suitable for potato plants grown from different types of planting materials, and for all end uses of these plants. The proposed scale is detailed enough for research and breeding but still general enough for agricultural use.

The investigation was carried out to study the growth of seven rice genotypes (Oryza sativa L.) under different levels of aluminum in the stress physiology laboratory, Department of Crop Physiology, Assam Agricultural University. Results obtained from the investigation revealed that higher levels of aluminum significantly influenced the growth of the genotypes. However, some tolerant genotypes viz. Rajamani and Rene Nepung Aam showed a better performance than the other genotypes by maintaining the Leaf area index, Specific leaf weight, Root biomass accumulation and other yield attributing characters (Panicle weight, Harvest index). Considering all these characters Rajamani and Rene Nepung Aam may be considered as tolerant genotypes under high aluminium conditions.

Over the last decade, LED lighting has gained considerable interest as an energy efficient light source in greenhouse horticulture. Much work on LED lighting is done under controlled conditions in the absence of sun light, whereas the primary application lies in supplementation of low light conditions in winter. A frequently forgotten aspect herein is that spectral composition may also affect the biology of pests and their natural enemies, both directly and indirectly through an impact on induced plant resistance. In this paper, we present results of trials with chrysanthemum and alstroemeria cut flowers which were exposed to lighting regimes with varying contributions of blue, green, red and far-red light. These trials were done under low levels of natural light, mimicking winter conditions. In chrysanthemum, spectra where blue or green were added did not affect stem length, plant dry weight and number of flowers when the percentage of red light remained over 75%. Replacing part of the photosynthetically active radiation (PAR) light by far-red light considerably increased stem length and (in some species) plant dry weight, at the expense of flowering. In alstroemeria, the number of flowers harvested, their length and fresh weight was largest in the treatment with equal shares of blue, green, red and far-red light. In chrysanthemum, the beneficial insect Orius laevigatus was introduced and its egg-laying activity and population development under different lighting strategies was monitored. The number of eggs laid by the first Orius generation was affected by the percentage red light in the spectrum, with the lowest egg number found in plants grown under 95% red. The results for egg-laying by the second Orius generation differed among chrysanthemum cultivars. The implications of this work on lighting strategies for greenhouse horticulture are discussed, both in spectral composition and in timing during the day and the season.

As earlier leaf removal experiments in tomato had shown that this improved dry matter partitioning to the fruits and production, a pilot experiment with high-wire cucumber was conducted in the spring and summer of 2016 at the experimental research facilities of Wageningen UR Greenhouse Horticulture. The five treatments were combinations of 3 or 3.5 stems m-2, and 0, 16 or 33% leaf removal in head of the crop. The combination 3.5/0% was lacking. The experimental data were analysed with the INTKAM crop growth model. The total number of fruits m-2 was the most important factor for production, which is determined by the optimal combination of stem density and assimilate supply. It is therefore important to grow the crop such that the maximum number of fruits with sufficient weight can be realized. Leaf removal in itself led to a slightly higher abortion, a lower development rate and therefore less axils, and a lower LAI with less light interception, and therefore produced less fruits and kilos. This, however, can be compensated with a higher stem density. It results in a crop with a normal LAI and architecture, combined with more axils m-2 that can bear fruits. Production and light use efficiency increase. On the other hand, labour and the risk to harvest small fruits will increase.

There is need for information on the general crop physiology and nitrogen (N) fertiliser responses of beetroot in New Zealand. We investigated the responses to N of beetroot grown in a silt loam ne...

Previous studies have shown that wool can adsorb contaminants present in the air. In this study it was determined how much ammonia or nitrous oxide could be absorbed by the untreated wool of each of three sheep races. In an airtight glass chamber supplied with a fixed amount of ammonia or nitrous oxide the concentration was monitored after a piece of wool was added. The wool of Schoonebeeker and Blauwe Texelaar sheep absorbed on average 0.11 g kg-1 ammonia, while Drentse heide sheep wool absorbed 0.09 g kg-1. Repeated additions of ammonia were absorbed at the same rate. For all wool types no absorption of nitrous oxide was observed. Research in cattle stables should be carried out to determine the real air purification of ammonia by installed wool material. Schapenwol bleek in eerder onderzoek luchtzuiverende eigenschappen te bezitten. In dit onderzoek is voor onbehandelde wol van drie Nederlandse schapenrassen bepaald hoeveel ammoniak of stikstofoxide wordt vastgelegd in de wol. Hiervoor is met luchtdichte meetstolpen en kunstmatig toegevoegde stikstofcomponent bepaald in hoeverre de concentratie in de lucht afneemt. Van de drie getoetste wolsoorten nemen de Schoonebeeker en Blauwe Texelaar wol volgens de stolpmetingen gemiddeld ca. 0.11 g ammonia kg-1 wol op, terwijl Drentse heide wol ca 0.09 g kg-1 opneemt. Herhaalde blootstelling aan ammoniak laat steeds weer vergelijkbare opname-hoeveelheden door de wol zien. Er vond geen opname van NO2 door de wol plaats. Onderzoek in de praktijk moet uitwijzen of het aanbrengen van schapenwol in stallen tot daadwerkelijke zuivering van ammoniak in de stallucht leidt.

Previous studies have shown that wool can adsorb contaminants present in the air. In this study it was determined how much ammonia or nitrous oxide could be absorbed by the untreated wool of each of three sheep races. In an airtight glass chamber supplied with a fixed amount of ammonia or nitrous oxide the concentration was monitored after a piece of wool was added. The wool of Schoonebeeker and Blauwe Texelaar sheep absorbed on average 0.11 g kg-1 ammonia, while Drentse heide sheep wool absorbed 0.09 g kg-1. Repeated additions of ammonia were absorbed at the same rate. For all wool types no absorption of nitrous oxide was observed. Research in cattle stables should be carried out to determine the real air purification of ammonia by installed wool material.

The technology of hybrid breeding in diploid potatoes creates opportunities to design novel and improved cultivation systems based on hybrid true potato seeds. A promising cultivation pathway to produce seed or ware tubers is by transplanting greenhouse-raised seedlings into the field. This study explored the effects of transplanting date and seedling age on tuber yield, using greenhouse-raised seedlings. Field trials with experimental hybrid genotypes were conducted in three consecutive years. In 2017 and 2018, 4- and 6-week-old seedlings were transplanted at four dates: March, April, May and June. In 2019, transplanting dates included April, May and June and seedling age was 5 weeks. In 2018, the March planting experienced severe frost during the initial field period resulting in crop failure. In 2017 and 2019, plants could withstand shorter and less severe frost events. Seedling age did not significantly affect tuber parameters. Transplanting in June resulted in lower marketable yield (> 28 mm) compared with earlier transplanting dates when crops were harvested in September. At full crop senescence, no differences in marketable yield were observed. The optimal transplanting window, taking into account weather-related risks, is approximately between early April and end May. For some genotypes, crop cycle length was observed to be a more important yield-determining factor than transplanting date.

Achieving the desired stem length is important in the winter cultivation of chrysanthemums under LED lighting. Earlier research showed that stem length under full-LED can be controlled by “end of day” lighting with 20 μmol/m²/s far-red light for 30 minutes. The question is whether the same effect can be achieved with a lower intensity or a shorter period of “end of the day” far-red light. Measurements on four chrysanthemum varieties grown under 200 mol/m²/sfull LED showed that the effect of 20 or 10 minutes of “end of the day” far red light was comparable to 30 minutes of 20 μmol/m²/s far red light. Reducing the intensity of the “end of the day” far red to 10 or 5 μmol/m2/s also had asimilar effect. To obtain this effect, lighting with “end of the day” far red light only during the first weeks of cultivation is not sufficient. The “end of the day” far red light has a greater effect on elongation or time to harvest than the lightspectrum during the day, where the proportion of green light was varied between 0 and 15% at the expense of red light. These results show that it is quite possible to grow chrysanthemums under full LED, and that there are sufficientpossibilities with light colors to control the crop in such a way that a desired stem quality can be achieved.

In this project a conceptual framework is made about different types of plant stress in a greenhouse cultivation. The aim is to get a better understanding of plant stress and to prevent the need for energy consuming actions when a plant is “out of balance”. What is plant stress? A plant strives for homeostasis: all chemical and physical processes are in balance with the environment. In a stress situation, a plant senses the change that disturbs the balance between plant and environment. The plant adapts to the new situation which leads to a new balance (acclimation). That means that stress can have a negative impact on the crop, but stress can also be beneficial. Crop and climate management both disturb the balance and steer the crop in the desired direction, which is considered as positive stress. The cultivation method “Next Generation Growing” aims for balances in crop and greenhouse. It is not always clear which actions lead to positive stress and which actions are negative for the crop. Monitoring plant balance or plant stress would be a helpful tool. But a lot is still unknown, like which plant processes should be monitored, what are critical values and what time period is needed for “a balanced crop”. In dit project is een denkkader opgesteld om na te gaan welke vormen van nuttige en negatieve plantstress er in de kas voorkomen. Het doel daarvan is om meer begrip te krijgen, en daarmee energievragende bijsturing te voorkomen als het gewas “uit balans” is. Maar wat is plantstress? Een plant streeft naar homeostase: dat betekent dat alle chemische en fysische processen in evenwicht zijn met de omgeving. Bij stress worden door de plant veranderingen waargenomen in de omgeving die leiden tot verstoring van het evenwicht tussen plant en omgeving die vragen om aanpassingen in de plant en deze leiden tot een nieuwe balans (acclimatie). Dat betekent dat stress negatieve effecten kan hebben op het gewas, maar dat stress ook nuttig kan zijn. Teelthandelingen die een teler doet om zijn gewas te sturen halen de plant uit balans en sturen de plant in de gewenste richting en worden beschouwd als nuttige stress. Het Nieuwe Telen stuurt op balansen in de plant en kas om te voorkomen dat het gewas uit balans is. Het is de vraag welke acties leiden tot nuttige stress en wanneer er negatieve stress optreedt. Het monitoren van plantbalans of stress zou hierbij een hulpmiddel kunnen zijn maar roept veel vragen op met betrekking tot welke onderliggende plantprocessen gemeten moeten worden, welke grenswaarden er gelden en over welke tijdsperiode “balans” gaat.

There is an ongoing societal debate about plant breeding systems and their impact on stakeholders in food systems. Hybrid breeding and hybrid seed have become controversial topics as they are believed to mostly serve high-tech agricultural systems. This article focuses on the perspective of commercial plant breeders when developing new cultivars of food crops. Arguably, hybrid breeding is the most effective breeding system for genetic improvement of crops, enhancing yields, improving product quality and increasing resistance against (a)biotic stresses. Nonetheless, hybrid breeding is not commercially applied in all crops. We analyse how biological and economic factors determine whether a commercial plant breeder opts for the hybrid system or not. We show that the commercial feasibility of hybrid breeding depends on the crop and business case. In conclusion, the commercial application of hybrid breeding in crops seems to be hampered mostly by high costs of seed production. Case studies regarding the hybrid transitions in maize, wheat and potato are included to illustrate these findings.

Powdery mildew on strawberry (Podosphaera aphanis) leaf and fruit is one of the most important diseases in strawberry. Mildew in strawberry depends on the number of spores in the air leading to infection, on the microclimate around the plant and on the variety. Germination of spores and mycelium growth takes place in the boundary layer close to leaf and fruit. This project looked at the influence of the microclimate in the boundary layer of leaf and fruit on mildew infection and how this may contribute to a management strategy of mildew. First, the thickness of the boundary layer was determined. Subsequently, the microclimate in this boundary layer was measured and climate data were compared with the greenhouse. With these data, a model of the microclimate was drawn up based on measured climate values in the surrounding greenhouse air, leading to a good predictability (R2=0.98). This makes it possible to calculate the microclimate in the boundary layer of leaves and fruits based on measured climate values in the surrounding greenhouse air without the need for specific microclimate sensors. Data from mildew incidence were collected and linked to the microclimate in the boundary layer. Microclimate settings that appeared to inhibit or promote mildew development were then tested in climate chamber experiments measuring mildew germination and mycelium development. It appeared that germination of mildew spores on young leaves is higher than on old leaves, that germination increases with an increase in relative humidity and that temperatures above 30oC inhibit germination. Mycelium development immediately after inoculation was not linked to the microclimate, while outwardly visible mycelium increased two weeks after inoculation at higher relative humidity. This shows that for mildew development, relative humidity appears to be a more important factor for the microclimate than temperature. Based on these data, a first model for the prediction of mildew germination depending on the microclimate was set up leading to a reasonable predictability (R2=0.79).

The development towards a sustainable and climate-neutral greenhouse horticulture requires zero emission, zero use of natural gas and the use of biological control of pests and diseases. The challenge is how to keep the crop productive and healthy with minimal energy input. To achieve this, the use of efficient lighting systems such as LEDs is essential. The fact that LED lighting can be adjusted in color offers new opportunities, but also raises questions regarding the most suitable light spectrum. This research shows that young tomato and cucumber plants can be cultivated well under different light spectra. The balance of blue and far-red light primarily determine the elongation, and thus the plant architecture. This allows the propagation and cultivation of crops towards the required plant morphology. Light spectrum did not affect plant weight and early fruit production of snack cucumber. A light spectrum with a higher proportion of red light is perceived by insects as higher light intensities, which improves reproduction and activity. This knowledge can be used to adapt the strategy to release natural enemies to the lighting conditions in the greenhouse. In een duurzame en klimaatneutrale glastuinbouw wordt gewerkt zonder gebruik van chemische gewasbeschermingsmiddelen en gas, en deze is vrij van emissies. De uitdaging hierbij is hoe het gewas productief én gezond kan worden gehouden met minimale energiekosten. Om dit te realiseren is het gebruik van efficiënte belichtingssystemen zoals LEDs essentieel. Het feit dat de kleuren van LED belichting instelbaar zijn, biedt nieuwe kansen om gewaseigenschappen te sturen, maar roept ook vragen op ten aanzien van het meest geschikte lichtspectrum. De experimenten in dit onderzoek laten zien dat de teelt van jonge tomaten- en komkommerplanten goed kan onder verschillende lichtkleuren, waarbij met name de balans tussen blauw en verrood licht de mate van strekking bepaalt. Daarmee kan tijdens de opkweek en de start van de teelt gestuurd worden op het telen van een plant met de gewenste plantvorm. Het lichtspectrum had geen effect op plantgewicht en op de vroege productie van snackkomkommer. Een lichtspectrum met een hoger aandeel rood licht wordt door insecten ervaren als condities met meer licht, wat de zoekactiviteit ten goede komt. Deze kennis kan gebruikt worden om de uitzetstrategie van natuurlijke vijanden aan te passen aan de lichtomstandigheden in de kas.

This repository provides access to the dataset used to conduct the meta-analysis on the productive performance of intercropping published in PNAS (DOI: 10.1073/pnas.2201886120). Three files are provided, named as “Dataset.csv,” “Variables in the dataset.xlsx”, and “R script.R”. The file “Dataset.csv” includes 934 data records collected from 226 field experiments on intercropping, described in 132 publications (see the Materials and Methods of the paper). Each row of this dataset corresponds to one record. The record descriptors are presented in 50 columns, providing information on the publication (title, year and authors), species combination, the yields and N fertilizer rates of both sole crops and intercrops, intercropping design, intercropping pattern, number of replicates and so on. The file named “Variables in the dataset.xlsx” includes the meta-data and define all the variables (columns) included in the file “Dataset.csv”. The file “R script.R” includes the R scripts used to analyze the data and generate the figures presented in the paper.

To combine the development towards sustainable and climate-neutral cultivation systems for all-electric greenhouses with lighting, efficient lighting systems such as LEDs are essential. LEDs have a high energy-efficiency and make it possible to apply dynamic light recipes, in which light intensity and spectral composition can be varied throughout the day and during the cultivation depending on the developmental stage of the crop. Knowledge on the effects of light spectrum is still limited for most crops, as well as the effect of spectral composition on the control of pests and diseases in the crop. In this project, we took an integrated approach that combines research on the effects of dynamic light spectra on the growth and production of eggplant, tomatoes and cucumbers with the effects on plant resistance to pests and diseases, incorporating the underlying physiological and genetic processes. The behavior of pests and natural enemies has been further investigated in chrysanthemum and sweet pepper. The results indicate that growth and production of greenhouse grown crops can be controlled with the light spectrum, whereby resistance to diseases and pests is a precondition. Om de ontwikkeling naar duurzame en klimaatneutrale teeltsystemen voor all-electric glastuinbouw te kunnen combineren met belichting zijn efficiënte belichtingssystemen zoals LEDs essentieel. LED biedt energetische voordelen en maakt het mogelijk om dynamische lichtrecepten toe te passen, waarbij lichtintensiteit en lichtkleur gedurende de dag en gedurende de teelt naar behoefte van het gewas gevarieerd kunnen worden. Voor de meeste gewassen is er nog maar een zeer beperkte kennis over de effecten van het lichtspectrum op het gewas, maar zeker ook over welke rol het lichtspectrum speelt in het beheersen van ziekten en plagen in het gewas. In dit project wordt een geïntegreerde benadering gekozen waarbij effecten van dynamische lichtspectra op de groei en productie van aubergine, tomaat en komkommer onderzocht zijn, met daarbij ook de effecten op plantweerbaarheid tegen ziekten en plagen, waarbij ook gekeken wordt naar de onderliggende fysiologische en genetische processen. In chrysant en paprika is het gedrag van plagen en natuurlijke vijanden verder onderzocht. De resultaten geven aan dat groei en productie van deze gewassen gestuurd kan worden met het lichtspectrum, waarbij de weerbaarheid tegen ziekten en plagen een randvoorwaarde is.

Anatomics is a novel phenotyping strategy focused on high-throughput imaging and quantification of plant anatomy from field-grown plants. Here we highlight its potential applications for genetic and physiological analysis of plant anatomical phenotypes.

We assessed how the temperature response of leaf day respiration (Rd) in wheat responded to contrasting water regimes and growth temperatures. In Experiment 1, well-watered and drought-stressed conditions were imposed on two genotypes; in Experiment 2, the two water regimes combined with high (HT), medium (MT) and low (LT) growth temperatures were imposed on one of the genotypes. Rd was estimated from simultaneous gas exchange and chlorophyll fluorescence measurements at six leaf temperatures (Tleaf) for each treatment, using the Yin method for non-photorespiratory conditions and the non-rectangular hyperbolic fitting method for photorespiratory conditions. The two genotypes responded similarly to growth and measurement conditions. Estimates of Rd for non-photorespiratory conditions were generally higher than those for photorespiratory conditions but their responses to Tleaf were similar. Under well-watered conditions, Rd and its sensitivity to Tleaf slightly acclimated to LT but did not acclimate to HT. Temperature sensitivities of Rd were considerably suppressed by drought, and the suppression varied among growth temperatures. Thus, it is necessary to quantify interactions between drought and growth temperature for reliably modelling Rd under climate change. Our study also demonstrated that the Kok method, a currently popular method for estimating Rd, underestimated Rd significantly and should be abandoned.HighlightLeaf day respiration (Rd) acclimated little to growth temperature, but significantly to drought by reducing its thermal sensitivity. The Kok method underestimates Rd and should no longer be used.

The potato is a complex plant. Above-ground it consists of a constellation of stems when grown from a seed tuber, but there is only one stem per seedling grown from true potato seed. Individual stems from both types of starting material can branch below-ground, above-ground at the base of the stem, and by apical branching at the top thus forming a sympodium consisting of stem segments, each ending in an inflorescence. Plants from true seed can branch profusely at the base giving them a bushy appearance. Below-ground branches can develop into stolons that may also branch and can produce several tuber sites and finally tubers. Early leaves are small but later appearing leaves can reach large sizes and are compound. They are imparipinnate with small leaflets between larger pinnae and with the rachis ending in one final top leaflet. This chapter describes in detail the development of the shoot system, the leaves and canopy, the stolon system, the tuber system, the inflorescence structure, and the (relatively weak) root system. It stresses the different fates of tuber incipients and tubers, the relations between above-ground and below-ground development, and the influence of propagule type and physiological age of seed tubers on plant and crop development.

When glass is laminated for safety reasons, it usually blocks UV radiation partially or even completely when UV blocking materials are used. In the last decade, there has been an increasing interest in interlayers with high UV transmission, especially in relation to greenhouse applications. In this paper, we present an overview of the effects of UV transmittance on plant growth and development, in order to advice on the use of the high transmission interlayers versus the standard interlayers. Using UV transmitting films instead of UV blocking films has opportunities to alter plant growth and morphology. In general, plants grow more compact with increased UV transmittance, growth and biomass are reduced, flowering is stimulated (although the effects are species dependent), concentrations of secondary metabolites which are positive from nutritional perspective are stimulated and flower appearance (color) can be positively influenced. Pollination by bees is improved when UV is present and plant resilience to pests and diseases is improved. These results show that UV transmitting materials can have potential to be used in for example botanical gardens, office centers and garden markets, where producing biomass might even be unfavorable. On the contrary, the increased ornamental value by improved shape and flower color will be appreciated. Therefore, these aspects of transmitting UV to plants can have potential for markets where plant production is not the main goal.

In a desk study financed by Kas als Energiebron, WUR and Delphy investigated the possibilities of fossil-free cultivation of woody soft fruit under glass. To this end, discussions were held with growers. In addition to a description of the current situation in woody berries, a literature study was conducted in which the results of national and international research on blackberries and raspberries, which mainly related to climate factors, were listed. Partly on the basis of this, an attempt has been made to provide a vision of a fossil-free future for woody soft fruit and what measures growers of blackberries and raspberries could take to achieve this. A number of knowledge gaps with regard to woody berries have also been identified.