Day-Length Sensitivity

gardenlad(6b KY)November 30, 2006

Based on some posts here, and private correspondence, I'm beginning to give a lot of thought to the idea of day-length sensitivity in beans.

I'd never considered it, before. But several people have mentioned that certain varieties are day-length sensitive.

I'm thinking this is a good topic for conversation. Anybody have any definative info on this? What varieites would you say are day-length sensitive? In which direction?

Are pole types more likely to be day-length sensitive than bush types? Why do you think that is?

Etc. Etc. And so forth.

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zeedman Zone 5 Wisconsin

Gardenlad, I think that pole beans do tend to be more day-length (or "photo-period") sensitive than bush varieties, and perhaps more so than we realize. This may be because they are, as a rule, older and more "primal" than the bush or "bunch" varieties, which were mostly developed in - and adapted to - the higher latitudes of the temperate zone.

Believe it or not, some degree of DL sensitivity is quite common among vegetables; but only onions & soybeans receive attention in the U.S. for that trait.

Most of the varieties that I have observed with severe DL sensitivity (including the true Rice Bean, winged bean, some adzuki beans, and an asparagus bean that I have from the Philippines) came directly from tropical areas. Some of those George mentioned came from Mexico. The "Nunas" popping beans (which are P. vulgaris) are unsuccessful here for that reason, and teams of commercial breeders working diligently were unable to remove its DL sensitivity. Many tropical vegetables (such as water spinach, chayote, & Malabar gourd) will only blossom during the equinox, when day length approaches 12 hours; many of the root vegetables from Central and South America (such as llacon) begin tuber formation at the same time. Unfortunately, that time is just before frost for most of us in the U.S.

Virtually all soybeans are DL sensitive; but to various degrees, depending upon variety. I performed an experiment this year (which I have yet to post) where I planted 3-4 week old soybean transplants at the same time as the seeds of the same variety. The results (of the 23 varieties that matured) fluctuated widely; but the difference in maturity was always less than the difference in planting dates. Transplants _will_ produce an earlier harvest; but there is not a day-for-day gain in maturity.

I know that many common pole beans are not DL sensitive, because I can compare the Days to Maturity for different regions in the SSE Yearbook, and there is little variation North to South. But I believe that some of the long-season beans (such as some of the "horticulturals") might be mildly DL sensitive. Most are not widely grown, so comparisons are difficult.

I am considering replicating the soybean experiment with some long-season pole beans, to determine whether their late maturity is due to day length, or whether they just require a longer period to reach first flower. I know that transplanting is helpful for my Northern location; but I would like to determine the nature the relationship, whether days earlier planted = days earlier harvested. I suspect that the relationship is not one-to-one, and that some beans are better adapted to the South not only because of the longer growing season, but because of the shorter day lengths at the lower latitudes.

    Bookmark   November 30, 2006 at 8:45PM
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gardenlad(6b KY)

>This may be because they are, as a rule, older and more "primal" than the bush or "bunch" varieties, which were mostly developed in - and adapted to - the higher latitudes of the temperate zone. Which would help explain, too, why we have so many regionally adapted pole beans; southern varieties that don't do well up north, and vice-versa.

George has mentioned that the black-seeded greasy he grows had no trouble maturing further south, but almost didn't make it in Oklahoma. If it's truly a day-length issue, then that would mean the black-greasy is a short day length bean.

The problem in my mind is that pole beans mature over a rather long length of time. With most varieties, we have maturation happening as day-length increases and then decreases. So there has to be something more to the equation.

Could be the heat index, perhaps? This flies in the face of all of Eliot Coleman's conclusions that light, rather than temperature, is the controling factor in plant growth.

But temperature does have an effect on legumes. We know, for instance, that butterbeans prefer having cooler nights in order to mature. But the question there is, how cool is cool? And how sustained does it have to be?

Even in onions day-length sensitivity may have been overstated. I've been conducting a series of experiments with long-day length varieties. Not only have they done well, so far, they've actually outperformed commercial versions of the same onions. My Cippolini, for instance, _averaged_ about 2 1/4 inches in diameter.

I've one more year of experimenting, and then I intend turning to short-day length varieites to see what happens with them.

    Bookmark   November 30, 2006 at 11:53PM
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It's definitely a complicated matter, one which I've observed over the years by moving back and forth between northern (40 degrees +, & 36 degrees presently) and southern (20 degrees latitude). The first time I observed day length sensitivity was when we went from Northern Indiana to Central New Jersey to Edinburg (very southern) Texas in one year. I planted Large Early Greasy in our back yard, in Edinburg, in February. The plants only reached about a foot in height, produced a couple of pods and then dried down. I assumed that it was on account of day length sensitivity.

When we moved to the state of Puebla, in Mexico, many garden varieties I tried, from my seed box wouldn't work. Sometimes it seemed to be on account of day length sensitivity. But sometimes it was because of temperature issues. In Puebla we often had extended periods of coolness coupled with extreme wetness. Then, other times it would become way too dry. The sun was so much stronger there even than in TX. We were at 7500 ft. altitude. The only pole bean, from my collection, which I tried, and which produced was Barksdale Wax Pole. But as it was maturing a little old campesino jumped the fence, pulled up all my vines and was last seen headed for the hills with that strange golden podded bean. No one in that village had ever seen yellow podded beans before. That was the end of my viable Barksdale seed until I got seed again, from Mike Deyo, in Killbuck, OH, in 1999, ten years later.
From 1988 until around 1994 were bleak gardening years for us. I almost always managed some sort of garden, but we were reeling at the huge changes in climate and cultural practices required to succeed. My seeds from the USA seemed too risky, in that they tended to flop in the new environment. I did have some success with squash. I got Warsaw Buff Pie Pumpkin (heirloom from Northern Indiana) to produce in the Sierra North of Puebla. But it was a battle, and the vines never got more than about 6' long. Production was marginal. On the other hand, a native squash would practically cover a house or large tree, producing hundreds of pounds of good squash!
When we moved to Hidalgo (high plateau/ desert with irrigation/ white alkali soil, with less traumatic fluctuations in temps), in 1994, I also came to head up an agronomy program at a private Bible Institute designed to train and help rural and indigenous Christian workers from six states. By that time I did know some things which worked well, and had Rabbitry (rustic style) down cold. I began to maintain a decent sized garden, in which I experimented with a number of things as well as began recuperating some of our family heirlooms, to the degree that I could get them to grow. Tennessee Cutshort grew and produced, but production never was very high and it never did get over 6 tall. Barksdale Wax Pole, on the other hand, seemed completely unaffected by day length and would grow as tall as it did here up North. Warsaw Buff Pie Pumpkin did better in Hidalgo than in Puebla, but that was obviously because we had more heat. In the Sierra North of Puebla, at high elevations, there were no c. moschatas, an that, with reason.

While in Mexico we acquired a number of varieties which we then brought back north when we returned in 2001. Some, like Mecatlán Black Half-runner (bean) were completely unaffected by day length. Others, like Tarahumara Pick Green Bean (pole), which would produce quickly, and at a moderate height, in Mexico, still produce here, but they grew much more rampantly and only flowered towards the end of the season. IÂve planted a number of beans which simply wonÂt flower up here, including every lima I collected from Mexico and Central America. Squash which we collected in Mexico, so far, have all produced up here. But usually they donÂt produce as well as they did "back home." I trialed one Hawaiian squash (ZauggÂs Pumpkin) last summer, and it never even flowered in OK.

With corn, IÂve grown varieties adapted to the Midwest USA which wouldnÂt top more than 2 ½ feet in Mexico. One corn I collected in Tlatlauqui, Puebla commonly reached 9 there. There it took 8 mos. to produce dry grain. I sent some to Glenn Drowns, and he said it topped 18 only tasseling a week or two before his frost in IA (I doubt he had over 130 days of growing season). This same corn, when grown in Veracruz, in hot country, very nearby to its native place but several thousand feet lower, produced in only 90 days and was a bit shorter than in Puebla.

I tried for 5 or 6 years to get a soy to grow at 20 degrees latitude, purchasing soy in the market place in Hidalgo. But all that soy was imported from the North. It would reach about 3" , flower and dry down. Finally, I followed the 20th parallel across the Pacific until hitting landfall in HI. Checking the Seed Savers Yearbook I found "Kahala," a soy developed at the U. of Hawaii. When I grew it in Hidalgo, it did great! I grew it in NJ and though it wasnÂt quite as robust, it did very well. Here in OK I planted it late and yet it did really well, nearly as robust as in Hidalgo. Go figure!

I have to quit for now. But let me say that all this is complicated by temperature. By temperature I not only mean highs and lows but also average temperature. Places IÂve been have often had either a wider fluctuation between high and low temps than we have here or else extended periods of cool (not frosting but very cool and wet) temps. Native varieties seemed adapted for these special conditions. When moved to our conditions these varieties donÂt tend to behave anything like they did "back home." I also believe that the soil and humidity affect how these plants perform.

My head hurts just thinking of all of this!


    Bookmark   December 1, 2006 at 1:09PM
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Hope I didn't "kill" this thread! Just threw out some observations, hoping they might help the group draw some conclusions.

Here are three more observations:

1) I've now grown two proven day length sensitive pole beans (Oaxaca Cream & Tarahumara Pink Green Bean)in Mexico (far south), NJ (relatively far north) and Oklahoma (sorta in the middle). They both had more reserved growth in Mexico and rampant growth in NJ and OK. But interestingly, they both flowered later in OK than in NJ! The only difference in my plantings was that they would have received some shade from structures nearby, when growing in NJ. I intend to test this possibility, in 2007, by growing them where they'll receive about 5 hours of shade a day. In NJ, in 2004, I had flowers on Oaxaca Cream Greasy by some time in September and viable (shelly) beans by Nov. 7. Here in OK the variety didn't flower until Oct. 3, and we never got seed. In NJ Oaxaca Cream was planted June 9. Here in OK I planted it May 22.

2)The summer of 04 in NJ was exceptionally cool and wet. Summer 06, here in OK was quite hot and dry.

3)I have observed day length sensitivity in bush beans. But it doesn't seem as common. This observation is purely anecdotal in nature.


    Bookmark   December 5, 2006 at 9:39AM
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I just bought 4 solar accent lights for the garden, on the off chance it might attract toads. They are supposed to shine for 12 hours when fully charged. I doubt they will give off much light, but might even dim increased light interfere with production of beans, peas, okra, corn or root veggies?
I might have to put a shade panel between the lights and plants, just in case.

    Bookmark   December 6, 2006 at 2:20AM
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jimster(z7a MA)

"Hope I didn't "kill" this thread!"

Not at all, George. Many of us will be quiet on this thread because we don't have the knowledge to contribute. But it makes good reading.


    Bookmark   December 6, 2006 at 1:50PM
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gardenlad(6b KY)

Happyday, will those lights be elevated or at ground level?

I don't imagine they'll make much difference either way (they don't put out much more than a soft glow, as I recall, and they're far from full spectrum). But they certainly should have no effect if at ground level.

    Bookmark   December 6, 2006 at 2:46PM
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One year in NJ we planted Tarahumara Pink Green bean by our front porch. We had a light on the porch and that year that bean wouldn't flower until later than usual. I finally got it to flower by telling everyone in the family not to use the light on the porch until after frost! I don't believe this was my imagination. The porch light did directly hit that planting of beans. Soon as we left the porch light off they started flowering. That light was just a plain 'ole light bulb!

I've heard similar accounts of people trying to get poinsettias to bloom when a stray light would hit them.

Now Happydays, I'm not talking about just any bean being affected. Most varieties known in this latitude would be affected very little if at all. These were beans from Mexico, which were clearly photo-sensitive.


    Bookmark   December 6, 2006 at 2:59PM
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Sorry folks, I believe my last post could be misleading. Happyday, just go with what Gardenlad said. Your accent lights really don't put out much light, as in a beam of light. I can't imagine that they'd cause you any problem.

    Bookmark   December 6, 2006 at 3:08PM
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Thanks guys. The lights will be just a few inches above ground level, to attract insects that toads might come to eat. I'll probably put them around the perimeter with a board between the lights and plants, just in case. If it attracts toads I'll post about it in the Vegetable Gardening forum.

George, Tarahumara Pink Green just sounds pretty, though I probably couldnt grow it here. I googled for it and found two(pops) interesting ghits(pops)

The second link also lists 3 Bird Egg varieties. It does not appear that Victory Seeds will release samples from the Futterman collection to the general public yet, sadly, but they do have some interesting varieties for sale from the Seeds link at the top

    Bookmark   December 6, 2006 at 5:04PM
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blueflint(z6a OH)

The most obvious day length sensitive bean I have grown is the 1500-year-old cave bean from the southwest. This thing would bloom but didnt set a pod until about September first. Within a couple weeks, the vines were covered with pods. Luckily first frost wasnt until mid October the last time I grew them. This bean also had the primitive habit of shatteringpods splitting and throwing beans everywhere once they start to dry down. Once pods yellowed but were still moist, I would pick them and put them in large boxes inside to finish drying so I wouldnt loose the seed. These are a nice large dry bean (very poor for green beans) with a nice flavor and kept their purple markings when cooked.

Nowwhat about high humidity bringing on pod set verses dry weather? Some Appalachian adapted beans (particularly Cherokee varieties) dont like lower humidity and wont set a pod. A blast from the hose across the foliage every couple days will set pods instantly.


    Bookmark   January 21, 2007 at 9:01PM
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zeedman Zone 5 Wisconsin

Blueflint, you may be on to something. There are at least two factors to pod set in legumes:
(1) Flowering, which may - or may not - be triggered by daylength.
(2) Fertilization. This involves not only the act of pollination itself (which in some cases requires pollinators) but the receptiveness of the stigma, and viability of the pollen.

While this discussion has centered mainly on the stimulation of the plant to bloom initially, blossom drop is also an issue.

In cases where the plant blooms but pods do not set, the environmental factors may be prohibiting successful pollination. There have been several discussions about this; whether the limiting factors are temperature, humidity, or both. Since individual varieties could respond differently, there may not be an all-inclusive answer.

The blast from the hose sounds like an interesting experiment, to attempt to stimulate pod set in hot weather. It would provide both cooling & humidity... so if done on a timer when the blossoms are most fertile, it might offer hope for some of the more temperamental varieties.

But if successful, it would not prove beyond doubt that heat & humidity were the limiting factors, because it introduces an additional element - agitation. Spray irrigation might provide some degree of "tripping", which could in itself assist pollination.

I have always hand irrigated, so I may have been inadvertently using this method to some degree; but with more attention to timing, it could possibly be made more effective. However, for purposes of pollination, only brief periods of watering may be necessary. Excessive irrigation runs the risk of promoting disease.

Last summer was a hot one here in Wisconsin, though not by Southern standards. I observed that some of my beans continued to set pods, while others dropped blossoms for weeks before setting pods en masse. My "days to maturity" observations for those varieties were almost useless. So I will attempt to use irrigation this year as a tool to pollination, in hopes that it will yield better results.

    Bookmark   January 21, 2007 at 10:55PM
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gardenlad(6b KY)

I reckon we're raising more questions than we have answers for. Maybe somebody from one of the ag schoolsl needs to read this thread, and set up a series of experiments.

It sometimes happens that we measure an effect but get the cause wrong. For instance, Blueflint's hose blasting introduces several possibilities. 1. his belief that by upping the humidity you promote bean set in some varieties. 2. Zeedman's idea of tripping; i.e., that the agitation is promoting pollen drop. 3. Artificial cooling. Some varieties just don't like the heat of high summer---with or without humidity. The foliage spray fools the plants into thinking that the cooler temps of fall are on the way. 4. A combination of these factors. 5. Factors which we have not yet identified.

What we are recognizing more and more, however, is that there are condition-specific varieties, that react to localized effects. You can't even just say, "these are northern, these are southern," because many varities are much more sensitive than that. For instance, Corkey, which does well in the middle south, does not do well in the deep south. I have great success with it, here in Kentucky, but it's not real happy when Fusion Power grows it in Alabama. Wish I had reports on it from the north.

The question is: Aren't all beans somewhat conditions specific? It's just some do a better job of adapting to a wider spread of those conditions?

Another question: How do maturation times relate to conditon-specificity? That is, are early maturing types more or less sensitive? And, related to this, what about pole vs. bush types? Is one or the other more sensitive?

Oh, Lord. My teeth ache!

    Bookmark   January 22, 2007 at 7:42AM
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blueflint(z6a OH)

Getting a little off topic but to the blossom setting I described above. I water regularly but only at the base, not splashing things much. A couple years ago, mid-summer I noticed some of my Appalachian Cherokee beans were blooming quite heavily and had been for a while but not a single pod had set. My thoughts were...these had adapted to different conditions originally, for many hundreds of years. The Appalachains have a wide range of conditions. One guess I keyed in on is the moist conditions, almost rain forest like in some respects (some areas...there are a lot of micro climates in the mountains). So, one late July day when watering, I blasted the whole row of pole beans. In two days, I blasted them again. After this, I had a tremendous pod set showing just 3 days later. The movement or agitation was a thought but I have a LOT of bumble bees around my beans and where they are planted, there is a good breeze moving them all summer from across a large field. Still no definite answer, only thoughts to ponder.


    Bookmark   January 22, 2007 at 10:41PM
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