Abnormal Seedlings Research Articles

Substratos e teor de umidade para o teste de germinação de sementes de Apuleia leiocarpa (Vog.) Macbr.

O substrato e a quantidade de água utilizada são fatores determinantes para a condução do teste de germinação, afetando o crescimento do embrião e a formação da plântula. Com este trabalho objetivou-se identificar o tipo de substrato e o teor de umidade mais adequado para a realização do teste de germinação de sementes de Apuleia leiocarpa. Os tratamentos consistiram nos substratos: papel toalha (RP) e mata-borrão (SP), umedecidos com volumes de água equivalentes a 2,0; 2,5 e 3,0 vezes a massa do papel seco; areia (SA) e vermiculita (SV) umedecidos com quantidade de água correspondente a 50, 60 e 70% da sua capacidade de campo. Os testes foram conduzidos em germinador na temperatura constante de 25°C. As variáveis avaliadas foram plântulas normais, plântulas anormais, primeira contagem de germinação, índice de velocidade de germinação, tempo médio de germinação e frequência relativa de germinação. O experimento foi conduzido em delineamento experimental inteiramente casualizado com três repetições de 50 sementes cada. A germinação das sementes não foi influenciada pelos volumes de água utilizados para umedecimento. Apenas os substratos apresentaram diferenças, sendo que o substrato papel toalha mostra-se adequado para o teste de germinação de sementes de Apuleia leiocarpa enquanto, o papel mata borrão não é recomendado para o teste de germinação desta espécie.

Evaluation of milk thistle (Silybum marianum (L.) Gaertn.) seed germination in relation to seed health and seedling emergence

Summary Introduction: : Milk thistle (Silybum marianum (L.) Gaertn.) is an important medicinal plant. Achenes of milk thistle contain sylimarin, protecting liver cells against toxic compounds. Objective: The aim of the research was to find an optimum method of evaluation of milk thistle seed germination. Methods: Ten seed samples were tested. The seeds were germinated: on top of blotter paper, on top of blotter paper after seed disinfection, between pleated blotter paper, in rolled blotter paper and in sand. Germination at the first and final counts, the percentages of abnormal seedlings and dead seeds were determined. The correlation coefficients between seed germination, evaluated with various methods, and seedling emergence were calculated. Moreover, fungi associated with seeds and diseased seedlings were identified. Results: The lowest percentage of normal seedlings was observed after germination on the top of blotter. Highly significant positive correlations were noted between seedling emergence and seed germination at the final count evaluated in rolled paper, between pleated paper and in sand. The fungi from genera: Alternaria, Fusarium, Penicillium, Trichoderma, Ulocladium and Verticillium were frequently identified on seeds and seedlings. Conclusions: Infestation with fungi significantly affected milk thistle seed germination and plant emergence. Germination in rolled blotter paper may be recommended for evaluation of milk thistle seed germination, as the most practical and significantly correlated with seedling emergence.

Quality assessment of pea (Pisum sativum L.) seeds using the controlled deterioration technique

A three-factor experiment was set at the Horticulture Laboratory, Hajee Mohammad Danesh Science and Technology University, Dinajpur to study the effects of the controlled deterioration (CD) on the pea seeds at the constant temperature of 350C. The 3 factors considered were: 3 pea seed sources (Rangpur Local/RL, Dinajpur Local/DL and Thakurgaon Local/TL); 3 ageing periods (0, 8 and 16 days); and 3 seed moisture contents (12, 16 and 20% MC). The 27 treatment combinations compared in the CRD with the 3 repetitions for the 8 arenas were: % germination, % abnormal seedlings, % dead seeds, % soil emergence and seedling evaluation test for the root and shoot lengths as well as their dry matter contents. Identical prototypes of notable (5-1% level) degradations were recorded everywhere. But the disparities were lucid under the extreme stresses. Moreover, highly noteworthy (1% level) relations were traced amid all the traits ranging from -0.9847 (soil emergence × abnormal seedling) to 0.9623 (soil emergence × normal seedling). So, the CD technique was very effectual in judging the physiological statuses of the seed sources studied. Thus, the germination test might be add-on by a vigor test, the latter of which could be assessed by quantifying the seedlings’ root and shoot lengths and/or their dry matter accumulations. Moreover, in the seed quality certification, the suitable limits of vigor for the chosen traits could also be got by this technique. But the seeds of several pea varieties should be exploited to fix-up the agreeable limits of the traits. Furthermore, to save time, the ageing period could be squeezed by raising the seed MC.

Germination, viability and longevity of horseweed (Conyza spp.) seeds as a function of temperature and evaluation periods

ABSTRACT: In Brazil, horseweed is one of the most important weeds because of the resistance to herbicides and high competitive for the crops. A large of losses were reported in major crops such as soybeans, wheat and corn, where the use a no-tillage system and the herbicide resistance promote better establishment. A correct understanding of the way temperature influences germination enables the prediction of the regions with the highest potential for colonization by this weed and thus facilitates its control. The objective of this study; therefore, was to discern the ways temperature affected the germination, viability and longevity of horseweed seeds. Testing was done at 10, 20 and 30°C, while evaluation occurred on days 0, 15, 30, 45 and 60. Seeds were packed in a nylon mesh bag (5x5cm), with 10g of upland soil (Yellow Red Argissolo, sandy loam texture), placed in transparent plastic boxes at 0 to 0.5cm soil depth, at the temperatures specified. Percentage of remaining seeds, first and second germination counts, abnormal seedlings, and dead, dormant, viable and non-viable seeds, were assessed. Horseweed seeds achieve secondary dormancy at 10, 20 and 30°C, while their quality and the longevity showed damage at 20 and 30°C temperatures.

English

The present study aimed to investigate the influence of different substrates, temperatures and storage conditions on shepherd's purse seed quality. It was evaluated in germination paper substrates Germitest®, vermiculite, sand and Plantmax®, and roller temperatures of 25, 30, 15-25 and 20-30°C. Longevity was measured by the temporal response to different packaging (paper, plastic and aluminum) and storage environments (laboratory and freezer). Germination percentage, germination rate index, percentage of normal, abnormal and dead seedlings were evaluated. The paper roll at 25°C provides an optimal condition for maximum germination potential and vigor. The storage for three months in freezer provides an increase in vigor in the seed without storing. The laboratory promoted reduction in germination potential from nine months of storage, with total loss of germination at 24 months. The combination of freezer and plastic packaging provide maintenance of seed longevity after two years of preparation. Key words: Germination, vigor, longevity.

Overexpression of 9-cis-Epoxycarotenoid Dioxygenase Cisgene in Grapevine Increases Drought Tolerance and Results in Pleiotropic Effects.

9-cis-epoxycarotenoid dioxygenase (NCED) is a key enzyme involved in the biosynthesis of abscisic acid (ABA), which is associated with drought tolerance in plants. An osmotic-inducible VaNCED1 gene was isolated from a drought-resistant cultivar of Vitis amurensis and constitutively overexpressed in a drought-sensitive cultivar of Vitis vinifera. Transgenic plants showed significantly improved drought tolerance, including a higher growth rate and better drought resistant under drought conditions, compared to those of wild-type (WT) plants. After water was withheld for 50 days, the upper leaves of transgenic plants remained green, whereas most leaves of WT plants turned yellow and fell. Besides the increase in ABA content, overexpression of VaNCED1 induced the production of jasmonic acid (JA) and accumulation of JA biosynthesis-related genes, including allene oxide cyclase (AOC) and 12-oxophytodienoate reductase (OPR3). Moreover, transgenic plants possessed advantageous physiological indices, including lower leaf stomatal density, lower photosynthesis rate, and lower accumulation of proline and superoxide dismutase (SOD), compared to those of WT plants, indicating increased resistance to drought stress. Quantitative real time polymerase chain reaction (RT-qPCR) analysis revealed that overexpression of VaNCED1 enhanced the expression of drought-responsive genes, such as ABA-responsive element 1 (ABRE1), ABRE binding factors 2 (ABF2), plasma membrane intrinsic proteins 2 (PIP2), C-repeat/DRE-Binding Factor 4 (VvCBF4) and ABA-insensitive 5 (ABI5). Although the development of transgenic plants was delayed by 4 months than WT plants, because of seed dormancy and abnormal seedlings, the surviving transgenic plants provided a solid method for protection of woody plants from drought stress.

An improved method of seed germination testing in Kabuli chickpea

An experiment was conducted during 2014-2015 to standardize the seed testing method in Kabuli chickpea MNK-1 by number of seeds and number of germination papers. Among the different testing methods 25 seeds per replication recorded highest seed germination percentage (91.58%), less number of fresh un-germinated seeds (1.91%), abnormal seedlings (4.00%), diseased seeds (2.33%) and significantly higher seedling vigour index-I and II (2215 and 6863), among the number of germination papers used 2+1 as in between paper method(Bottom 2 and one paper above) recorded significantly higher germination percentage (92.12%), less number of fresh un-germinated seeds (1.41%), abnormal seedlings (3.66%), diseased seeds (2.33%) and significantly higher seedling vigour index-I and II (2463 and 6900), when compared to other. Irrespective of number of germination paper and seeds used however, interaction of 25 seeds per replication and 2+1 between paper method of seed germination testing showed significantly germination percentage (96.50%), less number of fresh un-germinated seeds (0.00%), abnormal seedlings (1.00%), diseased seeds (1.00%) and significantly higher seedling vigour index-I and II (2844 and 7792) followed by 50 seeds per replication.

Longevity of Horseweed Seed Bank Depending on the Burial Depth

ABSTRACT: Horseweed (Conyza spp.) is considered as one of the major weeds occurring in the agricultural areas of South America, especially in Brazil. This species stands out from the other weeds due to characteristics such as large seed production, continued seed production, dispersion over long distances and resistance to 5-enolpyruvoylshikimate 3-phosphate (EPSP) and acetolactate synthase (ALS) inhibiting herbicides, features that increase their management. Therefore, this study aimed at determining the physiological quality and longevity of horseweed seeds over 12 months. The experiment was established under field conditions, using a randomized block design with four replications. Fifty horseweed seeds were distributed into 50 g of dry soil, placed in permeable nylon mesh bags (10 x 10 cm), which were buried at 1, 2, 4 and 8 cm of depth. Each month, for 12 months, samples were collected and washed with water, and the remaining seeds were submitted to germination test. The percentage (%) of remaining seeds, germination, abnormal seedlings, dead seeds, dormancy and viability were evaluated. It was found that the horseweed seed bank was reduced by 59 % over 12 months. Moreover, horseweed seeds develop a secondary dormancy, regardless of the burial depth. In addition, an increased burial depth increases longevity and physiological seed quality.

Toxicological Effects of Surface Water Exposed to Coal Contamination on the Test System Allium cepa

Process related to power generation, i.e., extraction and burning of coal, strongly affects the soil, water resources, and air quality. Pollutants generated by the coal mining can lead to a number of environmental problems and has become matter of global concern. This study has focused on to evaluate the cytotoxicity and phytotoxicity of surface waters collected in the surroundings of the Thermoelectric Power Plant President Medici-UTPM (Candiota, Brazil), through Allium cepa bioassay and physicochemical analyzes. Three water samples collected at points P1, P2, and P3 were compared to the negative control (NC) for all variables analyzed. The P2 sample resulted in the lowest mitotic index (MI) values (23, 33.1, and 40.7%), followed by P1 (23, 33.1, and 40.7%). However, the P3 sample had the highest MI values (50.2, 40.1, and 36.3%) and was the most mutagenic sample compared to NC and other treatments. Samples P1, P2, and P3 were phytotoxic to A. cepa, resulting in abnormal seedlings. Through physicochemical analysis, all collected water samples showed high electrical conductivity and turbidity, indicating an increase in the deposition of metallic ions and organic compounds in these samples. Based on these findings, we can conclude that the analysis of surface water is an important step for screening mining areas potentially contaminated by coal compounds. Therefore, our study points out some consequences of mining process, in terms of A. cepa bioassay as well as their harmful effect on physicochemical constituents of surface waters, indicating the need for environmental monitoring of this region.

Estresse hídrico e térmico na germinação de sementes de Leucaena leucocephala (Lam.) de Wit

Leucaena leucocephala (Lam.) de Wit (Fabaceae) is an arboreal species of wide use in the world, mainly for feeding ruminants in semiarid climate regions. Given its relevance, the aim of this study was to evaluate the effects of water and thermal stress on the germination and vigor of L. leucocephala seeds. The experiment was installed in 3 x 4 factorial arrangement, considering the water potential (0.0, -0.3 and -0.6 MPa) and temperature (25, 30, 35 and 40 °C) factors on the seeds germination performance. The variables evaluated were: germination, abnormal seedlings, first germination count, germination speed index and seedling performance (length and dry mass weight of root and aerial part). The reduction of the water potential from -0.3 MPa reduced the germination and seed vigor, indicating that the tolerance of the species to water stress in the germination phase is low. The temperature range of 25-30 °C is ideal for germination and seedlings initial growth, but the seeds continue to germinate under a temperature elevation to 35 °C. The L. leucocephala seeds are poorly tolerant to water and thermal stresses and, consequently, the germinative capacity and vigor are reduced with decreasing water potential from -0.3 MPa and temperatures above 30 °C.

GERMINATION AND VIGOR OF Bixa orellana L. SEEDS PRE-SOAKED IN A PLANT BIOSTIMULANT

The aim of this study was to assess the germination and vigor of Bixa orellana seeds that were pre-soaked in different concentrations of Stimulate® plant biostimulant. For the standard germination test, Bixa orellana seeds from the Embrapa 37 Cultivar were pre-soaked (for periods of four and eight hours) in the following concentrations of Stimulate® aqueous solution: 3.0; 6.0; 9.0; and 12.0 mL L-1. Seeds that were pre-soaked in distilled water were used as control. The following parameters were tested: germination; first germination count; abnormal seedlings; length; and seedling dry mass. The experimental design was completely randomized and a 2 x 5 + 1 factorial design was used (with two pre-soaking periods, five Stimulate® concentrations, and one additional control without pre-soaking). Four replicates of 50 seeds were performed for each treatment. Water immersion treatments for four and eight hours were efficient for breaking dormancy in Bixa orellana seeds, since they promoted better germination in relation to the intact seeds that were not pre-soaked. The pre-soaking of Bixa orellana seeds for eight hours in a 12.0 mL L-1 Stimulate® concentration presented the best results in terms of germinative performance and seedling growth, with greater accumulation of dry mass. Therefore, this practice is recommended for the production of seedlings of this species.

Germination and growth of ornamental pepper plants due to salinity

Seeds need favorable environmental conditions to germinate but sometimes these conditions are not available. The goal of this work was to evaluate the influence of different concentrations of NaCl on in vitro germination and development of Capsicum annuum seedlings. The experiment was conducted at the Laboratório de Biotecnologia Vegetal at Centro de Ciências Agrárias (CCA) of Universidade Federal da Paraíba (UFPB), Areia, PB, Brazil. Ornamental pepper seeds (Capsicum annuum L.) were submitted to five concentrations of NaCl: 0, 25, 50, 75 and 100 mM. The experimental design was completely randomized, with five treatments and seven replicates, each replicate consisted of one flask with one seed. After 14 days in vitro, the germinated seedlings were characterized for seedling height, hypocotyl width, cotyledon leaf length, cotyledon leaf width, leaf number, radicle length, fresh matter and germination. The data were submitted to analysis of variance by the F test ( p ≤ 0.05). When significant differences were detected, the data were submitted to regression analysis. Percentage of abnormal plantlets was also calculated and submitted to descriptive statistical analysis. The percentage of germination was not affected by the NaCl concentrations used in this work. However 75 e 100 mM salt concentrations influenced the cotyledonary leaf width, total fresh matter and percentage of abnormal seedlings.

ESTRESSE SALINO E HÍDRICO NA GERMINAÇÃO E CRESCIMENTO INICIAL DE PLÂNTULAS DE <i>Toona ciliata</i> M. ROEM. var. <i>australis</i>

A espécie florestal Toona ciliata var. australis possui madeira de alto valor econômico para móveis e seus plantios não são afetados pela Hypsipyla grandella, praga que ataca plantios de monocultura de espécies nativas semelhantes à Toona ciliata. Possui uma estreita relação com a água disponível, ocorrendo geralmente em florestas úmidas no seu ambiente natural. Em plantios comerciais esse é um dos fatores que mais limita seu estabelecimento e crescimento inicial. Nas últimas décadas, sua área de plantio no Brasil foi ampliada, entretanto, é escasso o conhecimento sobre o efeito de ambientes adversos na germinação e crescimento inicial de plântulas. O objetivo deste trabalho foi avaliar os efeitos do estresse salino e hídrico na germinação e crescimento inicial de plântulas de Toona ciliata, utilizando-se soluções contendo, ou NaCl, ou PEG 6000, nos potenciais osmóticos: -0,1; -0,2; -0,3; -0,4; -0,5; -0,6; -0,9; -1,2 e -1,5 MPa, mais a testemunha, com água esterilizada. As sementes foram submetidas ao teste de germinação sobre papel-germitest umedecido com a solução correspondente, e incubadas a 25 ± 2°C e fotoperíodo de 16 h por 21 dias. O delineamento experimental foi o inteiramente casualizado, arranjado em esquema fatorial 2 × 10 (agentes osmóticos × potenciais osmóticos e testemunha), com quatro repetições de 50 sementes cada. Conforme a redução do potencial osmótico observou-se menor germinação, número de plântulas normais, massa fresca, comprimento de plântula e maior número de sementes duras, sendo mais severo em PEG 6000. Portanto, houve mais sementes germinadas sob o efeito do NaCl do que do PEG 6000. Entretanto, apesar da germinação alta em NaCl, o número de plântulas anormais também foi maior que em PEG 6000. Conclui-se que a germinação e o crescimento inicial de plântulas de Toona ciliata são afetados tanto pelo estresse salino como hídrico, sendo as plântulas mais sensíveis ao estresse hídrico, e com maior probabilidade de desenvolver plântulas anormais sob estresse salino.

Physiological quality of soybean seeds under different yield environments and plant density

ABSTRACT Yield potential of agricultural fields associated with plant spatial arrangement could determine the physiological quality of soybean (Glycine max L.) seeds. Thus, this study aimed to evaluate the physiological quality of soybean seeds from different yield environments and plant densities. Experiments were carried out in Boa Vista das Missões-RS, Brazil, during the 2014/2015 growing season. Yield environments were delineated by overlapping yield maps from the 2008, 2009/2010 and 2011/2012 growing seasons. The experimental design was a randomized complete block in a 2 x 5 factorial arrangement with two yield environments (low and high) and five plant densities, with four replicates. Two varieties were tested: Brasmax Ativa RR (10, 15, 20, 25 and 30 plants m-1) and Nidera 5909 RR (5, 10, 15, 20 and 25 plants m-1). After harvested, the seeds were analysed as following: first count index, germination, abnormal seedlings, dead seeds, electrical conductivity, accelerate aging test, root length, hypocotyl length and seedling length. The spatial variability of seed vigor in the production field could be reduced by adjusting plant density, but the adjustment should consider the variety. Harvest according to yield environment is a strategy to separate lots of seeds with higher vigor, originated from high-yield environments.

Morphological and Physiological Germination Aspects of Anadenanthera colubrina (Vell.) Brenan

Anadenanthera colubrina is a species native to Brazil, from the Fabaceae family and has potential for use in the timber industry, in the reforestation of degraded areas, besides having medicinal properties. Its propagation is mainly by seeds, but basic subsidies regarding the requirements for optimal germination conditions are still lacking. Aiming to contribute to the expansion of its cultivation, rational use and conservation, the objective of this study was to investigate the morphology and anatomy of fruits and seeds, as well as the responses to factors as thermal regimes and substrates in seed germination. The 1000-seed weight and seeds per fruit were determined. To characterize the seed tissues, histochemical test with Sudan III and Lugol was used. The temperatures analyzed in the germination test were 15-25 °C; 25 °C; 20-30 °C and 30 °C. Different substrates for germination (paper rolls, paper sheet such as “germitest”, commercial substrate and sand) were also analyzed in the presence of light at 30 °C. The average number of seeds per fruit is 10 and the 1000-seed weight is 118 g. Germination is fast and high over a wide temperature range; however, the temperature of 25 °C contributes to a substantial increase in the percentage of abnormal seedlings and dead seeds, both in the absence and presence of light. A. colubrina seeds are indifferent to light and the highest vigor was verified at 30 °C. Sand and commercial substrates are efficient in initial seedling development.

Qualidade fisiológica de sementes de melão pepino sob salinidade crescente da água de irrigação

The Charentais cantaloupe melon Cucumis melo var.Cantalupensis Naud is a creole species that presents high adaptability to the edaphoclimatic conditions of the Northeastern semiarid, representing a food and income source. In this context, the purpose hereof was to evaluate the physiological quality of Charentais cantaloupe melon seeds subjected to irrigation with salt waters of 0.012, 2, 4, 6, and 8 dS m-1 in the germination percentage, first germination counting, germination speed rate, average time for germination, percentage of regular strong, regular weak, and abnormal seedlings, in the aerial part length, root length, length of seedlings and seedlings dry matter. The water’s salinity did not interfere in the Charentais cantaloupe melon seed germination process, but inhibited the main root’s and length of irrigated with water salinity over 3.8 and 4.3 dS m-1, respectively, and therefore superior to the maximum allowed of 3 dS m-1 in the conventional irrigation of most of the cultivated plants.

Ponašanje atipičnih klijanaca kukuruza u poljskoj proizvodnji

The aim of this study was to investigate field emergence parameters, number of plants that reached reproductive stage and yield of seed lots with different count of abnormal seedlings. In standard germination test these seedlings are discarded from the count of germinated seed, presuming that they will not develop into normal plants. Five lots of hybrid NS 640 with different percentage of abnormal seedlings were tested. Results showed that in favourable environment conditions, large number of abnormal seedlings emerged, reached reproductive stage and participated in yield formation. However, emergence of seed lots with high percentage of abnormal seedlings was longer than for lots with small number of abnormal seedlings. Laboratory germination and germination energy were more correlated with indicators of field emergence rate, while total percentage of germinated seedlings (normal and abnormal) was more correlated with grain yield. However, it can be expected that in adverse environment conditions, abnormal seedlings are less likely to develop into normal plants.

Thermal stress and physiological changes in watermelon seeds

ABSTRACT Given that watermelon is a crop widespread around the world, there is considerable interest in verifying how its seeds physiologically behave under unfavorable temperature conditions. This study aimed to evaluate the biochemical changes mobilization and reserves degradation, as well as the enzyme activity, during seed germination and initial growth of watermelon seedlings subjected to thermal stress, using temperature, germination percentage, germination rate and relative germination frequency over the incubation time as evaluation parameters. The experimental design was completely randomized, in a 5 x 3 factorial scheme, with five temperatures (17 ºC, 20 ºC, 25 ºC, 30 ºC and 35 ºC) and three cultivars (Charleston Gray, Fairfax and Crimson Sweet), with 4 replicates of 50 seeds. Germination, seedling growth, reserve degradation and stress protection system were evaluated. Thermal stress caused deleterious effects on watermelon seeds with germination capacity at well defined temperature limits, being 25 ºC the ideal temperature, with the highest percentage of normal seedlings. Sub- (17 ºC) and supra-optimal (30 ºC) temperatures presented more than 80 % of abnormal seedlings. The α-amylase enzyme activity is intense only at the beginning of germination. Under thermal stress, the proline contents increase mainly in the cotyledons.

Can mean germination time predict seed vigor of canola (Brassica napus L.) seed lots?

The aim of this research was to test if mean germination time (MGT) can predict seed vigor in 10 seed lots of canola. There was a significant difference between the final germination percentages of the 10 seed lots tested (‘Hyola 330’, ‘Hyola 401’, ‘Okapi’, ‘Elite’, ‘SLMO 46’, ‘Zarfam’, ‘RGS 003’, ‘Option 500’, ‘Echo’, ‘Rainbow’) and a highly significant correlation between MGT and this value. Of the 10 seed lots, ‘Hyola 330’ had the lowest final percentage germination (62%) and the highest MGT, 3.64 days. The correlation between MGT and the proportion of “normal” seedlings was also significant. ‘Hyola 330’ had the lowest percentage of normal seedlings (60%). A tetrazolium test showed that this lot had some dead seeds that could not germinate; some seeds were viable, but they would produce abnormal seedlings. One of the main reasons of low final germination percentage and high MGT in ‘Hyola 330’ was low viability of this seed lot. Mean germination time is suggested as a good indicator of seed vigor in canola.

Heat stress during seed development affects forage brassica (Brassica napus L.) seed quality

AbstractIn two consecutive seasons, forage rape (Brassica napus L.) plants were exposed to short periods (240°C hr) of heat stress (30°C day/25°C night) during seed filling (80% seed moisture content = S1), at physiological maturity (50% seed moisture content = S2) and at both S1 plus S2 (=S3) in a Biotron before being returned to the field until seed harvest. Seeds were hand harvested at 14% seed moisture content and their quality assessed by measuring germination, seed vigour (using the accelerated ageing and conductivity tests) and seed mass (as determined by thousand seed weight). Heat stress at both S1 and S2 caused a small (<10%) but significant reduction in germination in both seasons. There was a significant heat stress timing interaction in the first but not the second season. Reductions in germination were a result of increased abnormal seedling production not seed death. All three heat stress treatments significantly reduced seed vigour, with S3>S2>S1. Seed mass was reduced by heat stress at S1 but not at S2. Variable seed vigour in high‐germinating New Zealand‐produced forage rapeseed lots is most likely explained by short periods of heat stress during seed development.