OVERWINTERING AND YIELD OF WINTER CULTIVARS OF FIELD PEA ASSAS AND WHITE LUPINE ORUS

Janusz Prusiński
Department of Agrotechnology, Faculty of Agriculture and Biotechnology, UTP University of Science and Technology, Bydgoszcz, Poland

ABSTRACT

Two-way field experiment was set up in a randomized block design in four growing seasons: 2011/2012, 2012/2013, 2013/2014 and 2014/2015. Five methods were used when sowing winter cultivars of field pea Assas and white lupine Orus, as well as 5 methods of plant protection against stress conditions in the period of winter dormancy, mainly low temperature (only field pea). Both species were sown on three dates – the beginning of the third decade of September, the end of the first decade, and beginning of the third decade of October. In the season of 2011/2012, no plants of both these species were found after overwintering. In other seasons, the average winter pea density in spring was from 42.5 to 84.5 plants per 1 m². The studied methods of sowing and protecting plants of field pea did not also cause any significant increase in the level of plants’ winter survival. With quite favourable thermal conditions in winter season, seed yield of winter field pea Assas does not constitute competition for the constantly higher yielding spring forms of this species. White lupine was definitely more sensitive to a low temperature in winter season- plants overwintered only once with a satisfactory yield after sowing the seeds into white mustard or into stubble mulch.

Key words: legumes, winter cultivars, agronomy of sowing, overwintering.

INTRODUCTION

Height and stability of the yield of spring cultivars of legumes are strongly dependent on climatic conditions, especially on the amount and distribution of rainfall [10], while other factors, such as an extreme temperature or lack of nutrients, generally play a lesser role. The predicted gradual increase in the air temperature in the following years will contribute to expanding areas with water deficiency in the growing season, thus a greater significance will be taken on by species/cultivars resistant to drought or by cultivation technologies using post-winter water supplies more effectively [25].

Winter/overwintering forms, beside a longer period of accumulating biomass, are characterized by a more effective utilization of post-winter water [8, 18], while their better and quicker developed root system [9] in early spring than in spring forms, and also flowering earlier by 3–4 weeks [31] allow for avoiding unfavourable effects of dry spells in May and water deficiencies in the stage of developing pods and seeds, as well as negative effects of high temperature in June [14], owing to which they give higher and more stable yields than spring forms. In Poland, the average seed yield of stubble field pea in trials registered according to the Research Centre for Cultivar Testing (COBORU) [7] is about 4.5 t·ha^-1, while for white lupine almost 3.5 t·ha^-1 [6].

In many European countries, among other things in Spain [19], Germany [24, 30], Great Britain [9, 15, 17, 27–29], France [12, 13], Italy [2], Romania [8], Turkey [5], as well as e.g. in the USA [4, 14, 16, 23] winter/overwintering forms of field pea, faba bean and/or white lupine have been the subject of continuous research. According to the above mentioned authors, sowing date and developmental stage in which plants enter winter dormancy season, as well as the occurrence and thickness of snow cover determine their resistance to low temperature, overwintering and yield potential. In Poland, single papers have been published on the subject of winter survival of field pea of French strains L77 and L177, which was on average 51%, ranging in consecutive years from 0 to 92% [1]. There have been no studies on winter or overwintering cultivars of white lupine.

The aim of the study was evaluation of the possibility to cultivate winter cultivars of field pea and white lupine, selected from the EU Common Catalogue, on various dates and with various methods of sowing and other treatments aiming at plant protection, mainly due to a low temperature in the period of winter dormancy.

MATERIAL AND METHODS OF RESEARCH

The subject of research was winter field pea Assas with bipinnate leaves as well as winter white lupine Orus (both cultivars from Jouffray-Drillaud Plant Breeding, Cisse, France). The 2-way field experiment was set up in a randomized block design in 4 replications at the Experimental Station of the Faculty of Agriculture and Biotechnology of the University of Science and Technology (UTP) in Mochełek (53°13’N, 17°51’E, h 92 m a.s.l., zone 6B according to USDA – the estimated minimum temperature being from -17.8 to -20.5°C) in four growing seasons: 2011/2012, 2012/2013, 2013/2014 and 2014/2015.

Factor A was method of sowing and plant protection against unfavourable overwintering conditions (Tab. 1).

Spraying with chosen preparations (a6-a10) applied twice – in the season of 2013/2014: on 19^th November 2013 and on 10^th March 2014 and in the season of 2014/2015: on 22^nd November 2014 and on 25^th February 2015 r.

Factor B was the sowing time (Tab. 2).

Two-factor field experiments in 4 replications were set up on lessive soil, of a very good and good rye complex of a slightly acidic reaction, average to high content of P and K and a very low to low content of Mg. Before sowing, standard agronomic treatments were conducted – no mineral nitrogen fertilization was applied, basic rate of P was 60 kg·ha^-1, and K 80 kg·ha^-1. The forecrops were always cereals, after which Roundup 360 SL was applied at a rate of 2 dm³·ha^-1. The assumed plant density in both species after emergence was 110 and 80 plants per 1m², respectively. Before sowing, the seeds were dressed with ZN Sarox T 500 FS and inoculated with Nitragina (symbiotic bacteria). The area of the plot for sowing was from 22.08 to 30 m² gross. During spring vegetation, standard agronomic treatments were applied – double harrowing of the stands across the rows and spraying: onto monocotyledonous weeds – Fusilade Forte 150 (0.75 dm³·ha^-1) and onto bruchus – Proteus 110 OD (0.75 dm³·ha^-1) or Nurella D550 EC (0.5 dm³·ha^-1). Additionally, on some plots weeds were removed manually. Harvest date for field pea was in the second half of July and for white lupine it was the second half of August. In all research years, pigeons turned out to be a major problem in winter pea stands. The birds caused damage by eating immature seeds from pods.

Sampling and analysis – plant density per 1 m² was noted twice – just before the end of autumn vegetation and after the beginning of spring vegetation. Seed yield is given with 15% moisture.

Statistical analysis – statistical calculations were made with the use of program ANALWAR – 5.3 FR. The obtained results were subjected to the 2-way analysis of variance in a split-plot design. Significance of differences was verified with the use of Tukey test with α = 0.05. Means in tables denoted by the same letters for each factor did not differ significantly.

Meteorological conditions – the average monthly air temperatures below zero were noted in January and February 2011/2012, in December, January, February and March 2012/2013 and in January 2013/2014 (Fig. 1). In the season of 2011/2012, the absolute minimum of the surface air temperature at 5 cm at the end of January 2012 was -24.1°C at the ground surface, which along with the lack of snow cover caused total freezing of the plants of both species. Thus, synthesis of the results does not include this vegetation season. In the first decade of February 2013, the lowest temperature was -14.4°C, and in March up to -18.5°C, which however along with a several-centimetre snow cover allowed for overwintering of field pea plants. It should be emphasized that March 2013 was the coldest month at the Experimental Station since 1949 (the average monthly temperature being -3.5°C). The lowest temperature in the season of 2013/2014, i.e. -10.5°C was observed in January with a snow cover. In the season of 2014/2015, significant drops in temperature at the ground surface with a thin snow cover occurred many times, in December 2014 (from -7 to -13.5°C) as well as twice in January (-6.5 and -8.5°C), twice in February (-7.0 and -10.0°C) and twice in March (-6.0 and -8.0°C) 2015. The mean absolute minima of temperature at the Experimental Station in the years 1996–2015 were: in December -11.5°C, in January -15.0°C, and in February -13.1°C.

The average monthly rainfall in September, October and November did not differ much from the long-term rainfall total, which was favourable for plant growth in autumn (Fig. 2). Also snowfall in winter months, except for the season of 2011/2012, was favourable for winter survival of the plants.

After overwintering of plants, the course of weather in consecutive years of research was characterized by a significant increasing deficiency of rainfall in the period of pod development and seed filling, with slightly more favourable thermal conditions. The average long-term Selianinov index was 1.11, which means, except season 2015, sufficient availability of water for plants (Tab. 3).

RESULTS AND DISCUSSION

Plant density and health of plants entering winter dormancy
According to the recommendations of Knott and Belcher [15] and to the research results of Murray et al. [23], the standard of sowing of both species was raised by 10% compared with the optimum one for spring forms. Right after sowing and in the initial stages of plant emergence, minor losses of winter pea seedlings were observed, caused by birds, and in white lupine also because of more and more difficult conditions of plant growth, mainly in mustard stands. Field row emergence from the first sowing date occurred at the turn of the first and second decade of October, from the second sowing date – at the turn of October and November, and from the third one – in the first half of November. White lupine plants emerged slightly more slowly and were less advanced in development at the time of entering winter dormancy (around 10th November). The length of the autumn vegetation period from the consecutive sowing dates of both species was on average 44, 31 and 18 days.

Plants of winter pea cultivars which develop a rosette with small leaves and short internodes before the end of autumn vegetation, are characterized by the best winter hardiness [30]. On the other hand, winter cultivars of white lupine resistant to a low temperature lengthen internodes only after entering the stage of generative development in spring, and thus they are able to avoid frost damage [18]. According to Annicchiarico and Iannucci [2], plants of pea, faba bean and white lupine which are shorter though with an appropriate number of leaves survive winter better. In our studies, sowing date significantly varied developmental stage, in which plants of both species entered winter dormancy. Winter pea plants from the first sowing date developed on average 6–8 leaves, from the second date 4–6 leaves, and from the third date they took on a form of a 4–6 cm stem with  barely developing 2 leaves (Photo 1). The degree of development of white lupine plants was less advanced – plants from the first sowing date had on average 3–4 leaves, from the second date – 1–3 leaves, and from the third date – they developed cotyledons with the onset of the first leaf (Photo 2).

Preliminary results of phytopathological tests (2014/2015) carried out at the Department of Molecular Phytopathology of the University of Science and Technology (UTP) indicate a definitely better health of the aboveground parts and root system of pea. No symptoms of infection were observed on roots, while on leaves the disease symptoms were observed sporadically, within a range of 0 to 8% (Tab. 4–5). With the delay in the sowing time, root system was shorter and shorter, however with visible lateral roots and did not indicate any symptoms of pathogen infection (Photo 3).

Species composition and number of colonies of microorganisms isolated from the roots of white lupine in the season of 2014/2015 were significantly higher than in field pea, which might have been the cause of plant death even before the occurrence of extreme overwintering conditions [21]. Although the extent of the occurrence of disease symptoms on white lupine plants sown into stubble mulch was lower, the roots were also usually frozen, thin and partly blackened. This may indicate certain damages in white lupine plants even before winter, and a significantly lower resistance of plants of this species to a low temperature than in winter pea. Lateral roots were found only on plants from the earliest sowing date. The conducted isolations indicated that the main cause of the root rot were phycomycetes from the genus Pythium (Tab. 6, 7, Photo 4).

With a delay in the sowing time in both species, a slight decrease in plant density was observed in field pea (Tab. 8) and white lupine (Tab. 9), while on the third date a significant one, however the applied methods of sowing and treatments aiming at the protection of plants against unfavourable overwintering conditions did not significantly vary plant density.

Plant density and overwintering of plants after the onset of spring vegetation
Tolerance of plants to a temperature below zero depends on many factors, while the effect of a temperature alone on winter survival of plants is difficult to determine. Particular species may indicate various tolerance to a temperature below zero depending on the developmental stage, soil moisture, presence of a snow cover, or the duration of this temperature [21]. In the area of conducted research, the greatest drops in temperature are observed mainly in December, January and February. Frost hardiness is considered as one of the most important elements of winter-hardiness and denotes plants’ ability to survive short periods with significant drops in temperature without any negative consequences, especially freezing of water in cells and destroying viable tissues enabling new growth cycle in spring. According to Meyer and Badaruddin [21], in growth chambers LT50 i.e. temperature at which > 50% seedlings of pea underwent irreversible frost damage was from -4.5°C, while 1-week-old seedlings were more resistant to a temperature below zero than the older ones. Murray et al. [23] determined LT50 for pea as -8.5°C, emphasizing the need to carry out field studies to evaluate winter-hardiness of the plants. In Poland, Andrzejewska et al. [1] found complete freezing of field pea plants under field conditions at a temperature of -17°C. However, in Western European countries, absolute minima of temperature during winter dormancy in plants are usually significantly lower, e.g. in the experiment of Annicchirarico and Iannucci [2] they were from -3.4 to -7.3°C, and in south-west Germany -12°C [24]. Shereena and Salim [26] consider field pea as well-adapted to a wide range of temperature, and seedlings are able to survive a temperature even up to -20°C. In our studies, absolute minima of temperature were significantly higher and were: -24.1°C without a snow cover in January 2012, -18.5°C in 2013 with a snow cover, -10.5°C in January 2014 with a snow cover, and -13.5°C in December 2014, with a thin snow cover, while an average plant density in spring corresponding to these years was: 0; 28.8; 78.8 and 62.4 per 1 m².

The optimal sowing date for winter survival of pea plants in the UK falls on the end of October [15] to mid-November [29], in France – in mid-November [32], in Switzerland – in the second half of October [11], and in the USA in the second half of September [14, 16, 20, 23], with an average winter survival being around 50–86%. The long-term average plant density in field pea (2012/2013–2014/2015) was 56.4 per 1 m² (winter survival 57%) and was statistically similar on the control plot as well as when sown into stubble mulch, however it was significantly higher than when sown into furrows or after hilling of the plants. McPhee et al. [20] indicate a favourable effect of stubble height in direct sowing of winter pea, which similarly as in our studies aimed at retaining a snow layer over the plants. Muehlbauer [22] recommends sowing winter forms of field pea into narrow rows, which also increases mutual plant protection against low temperature. According to Silim et al. [29], application of PP 333 (paclobutrazol, ICI) significantly increased winter survival of pea plants from September sowing in Great Britain.

In consecutive combinations in the years 2013/2014 and 2014/2015, owing to a milder course of both winter periods, the average plant density in spring (84.4) was significantly higher, while winter survival was up to 82.7%, while neither the sowing date nor the applied preparations varied it significantly (Tab. 10). In literature, there is lack of information on the use of substances supporting winter legume plants against an excessive drop in temperature during overwintering. Irrespective of their specific properties and favourable effect on winter survival of other plants, we were unable to prove their significant effect on increasing winter survival and yield of field pea in our studies.

Frost resistance of white lupine plants sown in autumn depends on the size of the root system, the condition of apex as well as on the ability to harden vegetative organs, while an early sowing date of lupine – in mid-September in France guaranteed higher tolerance of roots to a low temperature [12, 13]. Leach et al. [17] state that only seedlings of white lupine with a well-advanced development of lateral roots and whose endodermis was completely lignified were able to survive winter well; young seedlings with slightly lignified roots were damaged by a 5-day exposure to a temperature of -10°C in special boxes. However, from a too early sowing date and connected with it overdevelopment of lateral roots in lupine, higher losses were also observed during overwintering of plants [3].

In our studies, in the growing seasons of 2012/2013 and 2014/2015 (absolute minimum of temperature -24.2 and -18.5°C) no or only single vigorous plants of white lupine were found after the onset of spring vegetation, despite autumn emergence slightly differing from the assumed ones on each sowing date and good condition of plants before entering winter dormancy in all years of research. In the season of 2013/2014 (absolute minimum of temperature -10.5°C) with the mildest course of temperature, mustard mulch and stubble mulch acted as a protection for overwintering plants, which allowed for achieving plant density enabling harvest from plots, while the average winter survival of plants was very low, did not reach 20%, however it was the higher the earlier was the sowing date, which guaranteed a more advanced development of the root system (Tab. 11), according to the  observations of Huyghe [12], Huyghe and Papineau [13], or Vocanson et al. [32]. Taking into consideration the occurring absolute minima of temperature, it seems that in zone 6B the success of cultivating winter cultivars of white lupine is unjustifiable due to an insufficient winter-hardiness and winter survival of the studied plant cultivars.

Seed yield
The results of some field experiments indicate pointlessness of sowing winter forms, whose yields are not higher than in spring forms, while their long growing season may cause problems with the health of plants and harvested seeds; moreover, sowing spring legumes in March or April does not expose plants to extreme thermal conditions [11]. However, in the years with a rainfall deficiency in the generative stage, significant drops are observed in the yield of spring forms of legumes [10]. Yet, winter legumes finish their growth in autumn almost always under favourable moisture conditions, with minimal evaporation and transpiration, and are ready for further vegetative growth at the moment when temperature increases in early spring [22, 25]. In many countries, e.g. Romania [8], France [18], as well as in Turkey [5] and the USA [14], seed yield of winter/overwintering cultivars of field pea was significantly higher than in spring cultivars. It should be highlighted that in some experiments, e.g. in Switzerland [11] and Great Britain [29], no higher yield in winter forms of field pea was confirmed than in its spring forms.

Seed yields of winter forms of field pea and white lupine are negatively correlated with plant density in spring [2], and according to Knott and Belcher [15], the highest yield of winter pea is obtained with 75–80 plants per 1 m². On average, in the long-term period of 2012/2013–2014/2015, the seed yield of winter pea (Tab. 12) was only 1.27 t·ha^-1 with an average plant density in spring of 56.4; the highest yield was obtained from the third sowing date (67.9 plants per 1 m²), where also the highest winter survival of plants was found. Such a low 3-year yield in pea resulted from an unexpected effect of Fusilade Forte, consisting in the strong inhibition of generative development of plants in the season of 2013/2014. Urbatzka et al. [30] did not find any significant effect of the sowing date on the yield of winter pea in Germany. In the seasons of 2013/2014–2014/2015, the average seed yield was 1.61 t·ha^-1 (with plant density of 84.4 plants per 1 m²); the applied spraying of plants with chosen preparations affected some increase in the seed yield of pea; after using Alkalin KB + Si the seed yield was significantly higher than with an increased fertilization with P and K as well as with preparation Pentakeep Super.

Sowing date is the main factor determining winter survival and yield of white lupine from autumn sowing and in south-west Germany occurs at the beginning of September [24], in Great Britain from the third decade of September until mid-October [3, 9], in Italy in the third decade of September and first decade of October [2], in Turkey until mid-November [5], in south Spain at the turn of October/November [19], and in the USA at the beginning of October [4]; on later dates the seed yield usually decreased by about 20–40%. Irrespective of the sowing date only in the season of 2013/2014 white lupine was only harvested from 16 plots, while from the last sowing date, the yield was not harvested at all due to a too low plant density (Tab. 13). Also, only mustard and stubble mulch protected the plants sufficiently to enable evaluation of the yield. In the first case, the seed yield was from 1.98 t·ha^-1 from the second sowing date, and 3.04 t·ha^-1 from the first date. Even better results were obtained after sowing white lupine into stubble mulch, on the first sowing date 3.70 t·ha^-1, including maximum yield in one of the replications 4.29 t·ha^-1. The obtained results confirm observations of Shield et al. [28] on a high variation in the yield of winter white lupine which was mainly dependent on the changeable course of overwintering conditions in the years and places of its cultivation or conducting research.

CONCLUSION

The applied methods of sowing and protecting plants of both species against stress conditions in the period of overwintering as well as sowing date did not significantly affect plant density after finishing autumn vegetation. In the study period, field pea plants did not survive winter only once (in the season of 2011/2012); in other years the average plant density in spring was 56.4 per 1 m², and winter survival was 57%. The studied sowing methods did not give the expected results in maintaining autumn plant density in spring. From additional treatments potentially increasing winter survival of pea plants, the most favourable ones seem to be ALKALIN KB + Si, Growon and Reflets. The effect of the sowing date on the yield of field pea was changeable over the years, which may indicate that the optimum sowing date of this species in Poland may be quite wide – from the third decade of September until the beginning of the third decade of October, with an indication of the later sowing date, both in terms of winter survival and yield. Under relatively favourable thermal conditions in winter, the seed yield of winter field pea Assas did not however constitute competition for the higher yielding spring forms of this species in Poland.

White lupine was definitely more sensitive to a low temperature in winter – plants overwintered (18.9%) only in one growing season (2013/2014), while vigorous plants were found in spring only from earlier sowing dates (the first or the second one) after sowing seeds into mustard or stubble mulch. In other years, from the applied methods and sowing dates in spring no or only single vigorous plants were found. From preliminary observations it also follows that there occurs a lower health of the root system in white lupine than in pea already in the period of entering winter dormancy.

Overwintering and yield of other cultivars of winter field pea from the Common Catalogue should be investigated for cultivation in Poland, the ones with higher resistance to a low temperature during winter dormancy, e.g. cultivars from Germany, Russia, Czech Republic, Finland or Lithuania than the ones from regions located in the significantly lower latitude.

Acknowledgments

This study was made possible by a grant from the Polish Ministry of Agriculture and Rural Development, Project: Improving domestic sources of plant protein, their production, trading and use in animal feed, 2011–2015.

REFERENCES

Accepted for print: 12.11.2016

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.