PRUNING METHOD FOR IMPROVED SEED PRODUCTION

Abstract

The present invention relates to a method for pruning pepper plants. In particular, pepper plants are pruned to a specific branch-architecture, whereby seed yield is increased.

Claims

1. A method for pruning an inbred line of a Capsicum plant, comprising: pruning a plurality of plants of the inbred line, wherein each plant comprises a stem, a first splitting and two branches, to a specific number of branches selected from 3, 4, 5, 6, 7 or 8, and optionally supporting at least one branch with at least one vertical twine, string or rope.

2. The method of claim 1, further comprising: emasculating flowers produced on said plants; allowing pollination of said flowers with the pollen of a second inbred line; allowing fruits to grow; and optionally, harvesting said fruits and collecting seeds from the fruits.

3. A method for producing seeds of Capsicum, comprising: pruning a first parent plant, wherein the plant is an inbred line, to a specific number of branches selected from 3, 4, 5, 6, 7 or 8; emasculating flowers produced on said plant; allowing pollination of said flowers with the pollen of a second parent plant, wherein the plant is an inbred line; allowing fruits to grow; and optionally, harvesting said fruits and collecting seeds from the fruits.

4. The method of claim 2, further comprising separating mature seeds from the less mature and/or immature seeds.

5. The method according to claim 3, wherein average mature seed yield per plant is increased by at least 10% compared to the average mature seed yield per plant when the same method is applied under the same conditions with the exception that the first plant is pruned to a conventional 2-branch architecture.

6. The method according to claim 2, further comprising treating the seeds by one or more of the following treatments: cleaning, washing, drying, hydrating, priming, disinfecting, selecting for viability, coating, pelleting, applying a composition comprising at least one insecticidal, fungicidal, acaricidal, nematicidal compound, a plant growth regulator or a biological control agent.

7. The method according to claim 1, wherein Capsicum plants are cultivated plants of the species Capsicum annuum, plant lines of sweet pepper, or inbred lines of sweet pepper.

8. The method according to claim 3, wherein the first and the second parent plants are inbred lines and the seeds of Capsicum are F1 hybrid seeds.

9. The method according to claim 1, wherein the plants are pruned every 3, 4, 5, 6, 7 or 8 days.

10. The method according to claim 1, wherein the plants are pruned every 3, 4 or 5 days.

11. The method according to claim 1, further comprising removing the weakest or inward facing head or shoot at nodes that are pruned.

12. The method according to claim 1, where 4 branches are left after pruning.

13. The method according to claim 1, where 5 branches are left after pruning.

14. The method according to claim 1, wherein the plants are grown at a density of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or 21 branches per square meter.

15. The method according to claim 1, wherein the plants are inbred parent lines of a pepper type of: Bell (blocky), Lamuyo type, Dulce Italiano, Dulce California, Dulce Hungario, snack type pepper, conical, capia, sweet charleston, dolma, cherry, jalapeno, shakira, pencil or hot Charleston, Sivri, Hungarian wax, Kapya/Florinis, banana, Fresno, Serrano, Ancho, Anaheim, Pasilla, Santa Fe, Scotch bonnet, or Habanero.

16. The method according to claim 1, wherein the plurality of plants comprise at least 20, 30, 40, 50 or more plants of the same genotype.

17. A plurality of pruned Capsicum plants of an inbred parent line of cultivated pepper produced by claim 1.

18. A plurality of pruned Capsicum plants of an inbred parent line of cultivated pepper, wherein all the pruned plants have a 3-branch, 4-branch, 5-branch, 6-branch, 7-branch or 8-branch architecture.

19. The plurality of pruned Capsicum plants of claim 17, wherein at least one branch of each plant is supported with at least one vertical twine, string or rope.

20. The plurality of pruned Capsicum plants according to claim 17, wherein said plants are capable of producing an average mature seed yield per plant that is at least 10% higher than the average mature seed yield per plant produced by a plurality of pruned Capsicum plants of an inbred parent line of cultivated pepper having been pruned to the conventional 2-branch architecture.

21. The method according to claim 9, wherein the plants are pruned every 5 days.

Description

LEGENDS OF THE FIGURES

[0138] FIG. 1: Schematic drawing of a plant pruned to a 3-branch architecture. Numbers indicate nodes. The vertical line with numbers 1-7 illustrates the stem. The first splitting is indicated by 0, from which point upwards the nodes are numbered again. The three branches are illustrated by lines having nodes 0 to 5, of which node 1 on the right side branch has not been pruned.

[0139] FIG. 2: Schematic drawing of a plant pruned to a 4-branch architecture. Numbers indicate nodes. The vertical line with numbers 1-7 illustrates the stem. The first splitting is indicated by 0, from which point upwards the nodes are numbered again. The four branches are illustrated by lines having nodes 0 to 5, of which node 1 on the right side branch and on the left side branch has not been pruned.

[0140] FIG. 3: Schematic drawing of a plant pruned to a 4-branch architecture from above, with the first splitting indicated by 0.

EXAMPLE

Materials and Methods

Layout

[0141] Different pruning methods were tested in the spring cultivation season in a Dutch greenhouse. Plants were raised in a nursery from January to mid/end of February, when they were transplanted into the greenhouse and pruned to a particular architecture during growth. In the greenhouse plants were grown on rockwool slaps. Plants were grown in a randomized block design.

[0142] Pollination was carried out in the beginning of April, maturation of fruits and seeds took place from end of April until mid-June. Due to time-constraint fruits were already harvested mid/end of May, although they would normally be harvested end of June or in July. However, seed numbers are not affected by an early harvest, only seed maturity is affected.

Pepper Varieties

[0143] For the inbred female parents of four pepper varieties (K1=Carson F1, K9=Bailor F1, K11=NUN55119 and K13=Soprano F1), the effect of pruning architecture on hybrid seed yield was tested in a Dutch greenhouse in the spring cultivation season. The female parents were grown in the greenhouse and pruned to a 2-branch (control), 3-branch or 4-branch or 7-8 branch architecture. Pollination was done with the male inbred parent, to generate F1 hybrid seeds in the fruits produced on the female parent.

[0144] K1 is a medium sized blocky pepper variety of Capsicum annum, which normally produces 10-12 fruits per plant under good growing conditions. The pollination period in this trial was 21 days from 21st March (first emasculation) till 12.sup.th April (last emasculation).

[0145] K9 is a lamuyo pepper variety of Capsicum annum with big fruit size, which produces between 5-6 fruits in one cultivation cycle. The pollination period in this trial was 19 days from 22.sup.nd March (first emasculation) until 11.sup.th April (last emasculation). The pollination period of 19 days was the shortest in the trial. Further the plants were also the shortest in comparison to the other three varieties.

[0146] K11 is a big sized pointy pepper variety of Capsicum annum which produces 12-15 fruits per plant under good growing conditions. The pollination period of this variety was the longest in this trial with one month from 20.sup.th March till 20.sup.th April.

[0147] K13 is big sized pointy pepper variety of Capsicum annum with an average fruit production of 12-18 fruits per plant. The pollination period of this variety was 27 days from 22.sup.th March till 19.sup.th April.

Treatments and Determinants

[0148] For the female parent of K1 and K9, the 2, 3 and 4 branch architecture was tested for 21 plants per branch architecture at 3 plants/m.sup.2 and for 18 plants per branch architecture at 2.6 plants/m.sup.2. For K11 and K13, the 2, 3, 4 and 7-8 branch architecture was tested for 18 plants per architecture at 2.6 plants/m.sup.2. The respective 21 and 18 plants were spread over the greenhouse in 3 repetitions (a, b and c) of each 7 (total of 21) or 6 (total of 18) plants, respectively. A combination of a plant variety, pruning architecture and plant density is denominated herein as a treatment. Per treatment, the average number of flowers, average number of fruits, average seed yield per fruit and average total seed yield per plant was determined (by multiplying the average number of fruits per treatment with the average number of seeds per fruit).

[0149] As plants can only maintain a certain amount of flowers to grow out into fruit (due to abortion) a surplus of flowers were pollinated with pollen of the male parent line. The total average number of fruits per plant (excluding parthenocarpic fruits, which are easily recognized since they are shorter and misformed) was used as a base to calculate the total average seed yield per plant. The total average seed yield per plant of a particular treatment was established by multiplying the average number of fruits of that particular plant with the average number of seeds per fruit of that particular treatment. The average number of seeds per fruit of a particular treatment was established by harvesting all fruits from three representative plants of that particular treatment, counting the total number of seed comprised in these fruits and dividing this total number by the number of harvested fruits from these three plants.

Trial Scheme

[0150] The trial started on February 28.sup.th with transplanting the female parent lines of K1 and K9 plants from the nursery into the greenhouse. The same was done for K11 and K13 on March 5.sup.th. Pollination occurred around March 20.sup.th to around Apr. 20, 2014 (see above for the details per variety). Fruit counts, forming the basis of the results presented in Table 1, were performed on May 14.sup.th, for K1 and K9 and on May 28.sup.th, for K11 and K13.

Pruning

[0151] The plants of the trial have been pruned every 5 days in order to obtain and maintain the specific pruning architecture of the specific plant, i.e. a 2-branch architecture (control plant), or a 3 or 4 or 7-8 branch architecture as defined herein. Pruning was done throughout the trial, up to and including harvesting the fruits. The 2-branch architecture was reached and maintained by keeping the two shoots of the first splitting and removing one of the two heads (or growing points) of each new internode formed after the first splitting. The 3 and 4 branch architecture was reached by keeping the two shoots of the first splitting and not pruning one (for the 3-branch architecture) or two (for the 4 branch architecture) or 5-6 (for the 7-8 branch architecture) later nodes and removing all supernumerary heads or shoots. The supernumerary heads or shoots were removed as soon as the shoot was big enough to be removed easily. For each pruning architecture, the weakest and latest formed head or shoot of the node was removed. Mostly, the weakest head or shoot of a node is the inward facing head or shoot of that node. However, in case the outward facing head or shoot of a node was weaker as compared to the inward facing one, the weakest head or shoot was removed.

Pollination

[0152] Pollination was performed by hand in order to produce hybrid seed. Female inbred lines were emasculated to prevent self-pollination and the male inbred line was used to collect the pollen used to pollinate the female line by hand. To collect the pollen, all flowers on the male line were picked and then the anthers were removed and collected. The anthers were sieved and the pollen was collected. Small glass tubes, a bit wider than the stigma of the pepper flower, were filled with the pollen. The tube was gently pushed against the stigma to pollinate the flowers (pollination). To check the right moment of pollination, one (mostly emasculated) flower was marked to assess the moment the flower opens as this would be the stage the emasculated flower would be naturally pollinated. The pollination process was mostly done two days after emasculation when the stigma is perfectly susceptible for pollination, in the morning from 9.00 to 12.00 AM.

Statistical Analysis

[0153] Per treatment, the effect of plant density and branch architecture on average fruit number, average seed yield per fruit, and average seed yield per plant was established. All data collected was statistically tested with a Univariate test to investigate effects of and interactions between treatment variables. In case of a significant effect or interaction was found, a post hoc analysis was executed to investigate the effects or interaction in detail. The program used for the analyses was IBM SPSS 19. Effects and interactions with a p-value of less than 0.05 were indicated as significant.

RESULTS

[0154] Table 1 shows the average amount of seeds per fruit, the average amount of fruits and the average amount of seeds per plant per treatment.

TABLE-US-00001 TABLE 1 Plant Average Average Average density Branch amount of amount of amount of % of (plants/ architec- fruits* per seeds per seeds per con- Variety m2) ture plant fruit plant trol K1 3 2-branch 5.4 55.4 301 100% (control) 3-branch 6.0 95.0 565 187% 4-branch 6.9 103.2 708 235% 7-8-branch 7.4 74.4 553 183% 2.6 2-branch 5.4 82.7 446 100% (control) 3-branch 6.9 87.5 603 135% 4-branch 6.7 74.0 498 111% 7-8-branch 8.1 98.4 793 177% K9 3 2-branch 4.3 94 408 100% (control) 3-branch 5.2 135 698 171% 4-branch 6.4 132 841 206% 7-8-branch 7.8 135 1058 259% 2.6 2-branch 4.7 108 509 100% (control) 3-branch 5.7 123 705 138% 4-branch 6.5 166 1081 212% 7-8-branch 7.3 121 884 173% K11 2.6 2-branch 7.6 207 1568 100% (control) 3-branch 9.6 211 2032 129% 4-branch 9.9 209 2066 131% 7-8-branch 10.9 201 2184 139% K13 2.6 2-branch 9.0 254 2283 100% (control) 3-branch 10.8 245 2649 116% 4-branch 12.4 223 2759 120% 7-8-branch 13.1 246 3228 141% *excluding parthenocarpic fruits

[0155] Below the results per variety are given in further detail.

K1

[0156] No significant effect of plant density on fruit production was found (p=0.113). A significant increase in total average number of un-aborted and seed containing fruit was found per increased number of branches (p<0.013), except between 3 and 4 branches (p=0.264). No significant effect of plant architecture and/or plant density on amount of seed per fruit was found. The average amount of seed per plant increased significantly relative to the control per increasing number of branches in the pruning architecture, but there was no significant difference between the 3 and 4-branch architecture. No significant difference was found between different plant densities within pruning architectures.

K9

[0157] A significant interaction between average fruit number and pruning architecture was found (p=0.00). No significant effect of plant architecture and/or plant density on average numbers of seeds per fruit was found. In general, a significant increase in the average number of seeds per plant was found with an increased number of branches. There was however no significance difference between the 4-branch and the 7-8 branch architecture. No effect of plant density on total seed yield was found.

K11

[0158] A significant interaction between average fruit number and pruning architecture was found (p=0.00). The average number of fruits per plant increased significantly with an increase in branch number, for example the 3-branch architecture resulted in a significant increase in the average number of fruits per plant compared to the control (p<0.01). There was however no significant difference between the 3, 4 and 7-8 branch architecture regarding average number of fruits produced. Total average seed number per plant increased significantly in the 3-branch, 4-branch and 7-8 branch architecture as compared to control.

K13

[0159] The 3-branch, 4-branch and 7-8 branch architecture resulted in a significant increase in average number of fruits compared to the control (p<0.01). There was no significant difference between the 4 and 7-8 branch architecture. No significant effect of branch number on average number of seeds per fruit was found. The average number of seeds per plant increased significant for the 3-branch, 4-branch and 7-8 branch architecture, but there was no significant difference between the 3-branch and 4-branch architecture.

CONCLUSION

[0160] As can be seen from Table 1 above the average amount of F1 hybrid seeds produced per plant was significantly higher in a 3-branch, 4-branch and 7-8 branch architecture compared to the control. A further benefit of a pruning architecture of 3, 4 or 7-8 branches is that the pollination period was shorter, since the fruit were found to develop faster and more simultaneous. It was found that the pollination period can be shortened by at least 6 days without negatively influencing seed production (data not shown). Due to lower labour costs, a shorter pollination period will result in cost saving. In addition, it was found that an increase in the number of branches per m.sup.2 had a positive effect on seed yield.