Com­pe­ti­tion for light makes plants see red

Central Otago Mirror - - FEATURES -

Have you ever no­ticed feel­ing dif­fer­ent in dif­fer­ent rooms? A room painted with red walls can make you feel en­er­gised or ex­cited, while a room with blue walls can pro­mote calm­ness and re­lax­ation. It turns out the same could be said for plants and an­i­mals in the gar­den. Re­searchers at the US Agri­cul­tural Re­search Ser­vice in South Carolina dis­cov­ered that red plas­tic mulch (plas­tic sheet­ing) can en­er­gise your to­ma­toes. Also known as se­lec­tive re­flec­tive mulch, it can pro­duce up to 20 per cent higher yields than tomato plants with­out it. This is not a new study. I re­mem­ber the idea of red plas­tic mulch be­ing bandied about six or seven years ago when I was edit­ing Week­end Gar­dener mag­a­zine. At that time plas­tic mulch wasn’t read­ily avail­able, but you can now get it on­line. So how does that work? Well, just like you and me, phy­tochromes, which reg­u­late growth and de­vel­op­ment, re­act dif­fer­ently to dif­fer­ent colours (wave­lengths in the light spec­trum), par­tic­u­larly in the red or far-red range. Light re­flected from the red mulch has a lower red to far-red ra­tio than nor­mal sun­light. When the far-red light wave­lengths re­flect off the red plas­tic mulch onto the tomato plants, the phy­tochromes kick into ac­tion and tell the plant to grow faster and pro­duce more. The rea­son for this is that far-red wave­lengths are not pho­to­syn­thet­i­cally ac­tive. In other words, they don’t fuel plant growth. In­stead, they en­able plants to re­act to the en­vi­ron­ment. Green leaves re­flect far-red light, so if there are a score of other plants nearby, a tomato plant will sense a high ra­tio of far-red to red light. In ef­fect, its sens­ing com­pe­ti­tion for sun­light, which prompts it to put on a growth spurt so that it can bet­ter com­pete for light. By lay­ing down red mulch the re­searchers dis­cov­ered they could ef­fec­tively trick the tomato plants into be­liev­ing there was a lot of com­pe­ti­tion close by and in­duce faster growth. The same re­searchers tri­alled red plas­tic mulch be­neath straw­berry plants and found the plants to pro­duce a higher yield, larger berries and a higher su­gar con­tent. They also re­ported that a blue plas­tic mulch un­der turnips pro­duced a stronger flavour whereas a green mulch pro­duced a mild, al­most sweet, flavour. Other re­search sug­gests that a green mulch was good for pep­pers and mel­ons, while a blue one ben­e­fited egg­plants. Bear in mind that coloured mulches may work bet­ter in dif­fer­ent parts of the coun­try, how­ever. Re­search at the Univer­sity of Florida found that red, green or blue plas­tic mulch gave no ben­e­fit to crops in that state. They con­cluded that coloured mulches worked bet­ter in cooler parts of the coun­try.

What's your wave­length?: Re­searchers at the US Agri­cul­tural Re­search Ser­vice in South Carolina dis­cov­ered that red plas­tic mulch laid un­der plants, in­clud­ing straw­ber­ries, can pro­duce higher yields.

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.