Corn plants appreciate a stress-free summer

first_imgShare Facebook Twitter Google + LinkedIn Pinterest Over the next several weeks the upper canopy in Ohio corn fields will look much different, as tassels begin to emerge and extend beyond the top leaves of the plant. This visual change signifies that the corn crop will soon be shifting from vegetative into reproductive growth. The first reproductive growth stage (R1) begins when silks extends outside of the husk leaves and typically occurs two to three days after tassel emergence.The two basic processes that occur during corn reproduction are pollination (transfer of pollen grains from the tassel to the silks) and fertilization (joining of the pollen grain and ovary to create an embryo). Though these processes seem very simple, there is a lot riding on their success. Approximately 85% of the variability in grain yield is related to the number of kernels produced per acre while the remaining 15% of the variability in grain yield is related to the weight of these kernels. Thus, failure in either of these reproductive steps can have a detrimental effect on yield.The most stress-susceptible period in corn is about one week prior to silking and continues for two weeks after silking. The timing of the stress can result in dramatic differences from one field to the next. A very small variation of even just a day or two difference in flowering date or planting date can cause a substantial effect in the success of pollination and kernel set. Water stress is the most common stress factor in corn, although high temperatures and loss of leaf area — from hail, diseases, insects, etc. — can also reduce yield during this critical time especially when coupled with drought stress.Severe drought any time during plant development can have a negative effect on yield potential, but the greatest impact is when drought stress occurs during the pollination and early grain-fill stages. Research at Iowa State University has shown that yields can be reduced by as much as 40 to 50% when corn undergoes four consecutive days of severe stress during the pollination phase. Moisture stress that occurs during the vegetative growth stages or during later grain fill has much less effect on yield. Stress effects from drought that takes place from one week prior to tasseling through the milk stage causes lack of ovule fertilization or kernel abortion. Moisture stress that occurs from the dough stage to black layer will lead to reduced kernel weight.The greatest risk of kernel reduction at pollination is the asynchrony of pollen shed and silking. Drought stress tends to accelerate pollen shed while delaying silk growth, which can result in poor “nick” of the pollen and silks. A single plant will shed pollen for only about five days but because of natural field variability in plant development a whole field may take up to 14 days to complete pollen shed. Silks begin elongating from the ovules of the ear shoot about seven days prior to emerging from the ear shoot. Silk growth occurs by cell expansion, so if a plant lacks the necessary water than silk development will be slowed or halted. Silks that emerge after most of the pollen is shed will not likely be pollinated. Moderate silk delay can cause poorly-filled ear tips, whereas more severe stress can result in ears that are nearly or completely barren.Corn maximizes its growth rate at 86 degrees F during the day and 60 to 65 degrees F at night. When daytime temperatures reach into the 90s, then plant stress results. High daytime temperatures decrease photosynthesis efficiency, which causes the plant to make less sugar that will in turn be used to produce plant biomass and grain. High night temperatures on the other hand can be even more detrimental to corn than high daytime temperatures. Elevated nighttime temperatures increase the respiration rate, causing the plant to spend more energy for the maintenance — energy that could have otherwise been used in dry matter accumulation. The respiration rate of plants increases rapidly as the temperature increases, approximately doubling for each 13 degree F increase. With high night temperatures more of the sugars produced by photosynthesis during the day are lost, which leave less available to fill developing kernels. High nighttime temperatures also result in a shortened grain fill period that will limit the time the crop has to add additional starch to the kernels.Curious to know how successful your corn fields were at pollinating? Follow the steps below and find out.1. Remove the ear from the plant.2. Gently peel the husks from the ear so that the silks are disturbed as little as possible.3. Grab the ear by the base and hold the ear so that the tip is pointing toward the ground.4. Gently shake the ear. Silks will fall from fertilized ovules, while silks of ovules not fertilized will remain attached to the developing ovules.5. Percent pollination is equal to the percent of ovules with no silks attached.last_img read more

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Nagaland recalls all police personnel on leave

first_imgThe Nagaland government has recalled all police “officers and personnel on leave” amid fears in the State about a possible breakdown of the peace process.On Monday, the office of Nagaland’s Director-General of Police issued a wireless transmission message to all unit heads banning all kinds of leave.The office of the State’s Chief Secretary issued a similar message asking all Deputy Commissioners and Administrative Officers to remain in station and recall all officers not on medical or maternity leave.The recalling of all police personnel has come three days after the Centre rejected the twin demands of the extremist Isak-Muivah faction of National Socialist Council of Nagaland (NSCN-IM) for a separate “Naga national flag” and “Naga Yezabo” (constitution).The Centre and NSCN-IM have been pursuing a peace process since signing a ceasefire in August 1997.last_img read more

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Melindo retains jr fly title by split decision

first_imgA bloodied Milan Melindo knocked down Hecto “Hekkie” Budler in the 12th and final round Saturday night to salvage his International Boxing Federation junior flyweight crown by split decision at Waterfront Hotel and Casino in Cebu City.Coupled with a strong 11th performance, Melindo, who sustained cuts in both eyes, toppled the tough South African in the headliner of Pinoy Pride 42: Clash for Glory.ADVERTISEMENT ‘A complete lie:’ Drilon refutes ‘blabbermouth’ Salo’s claims Lacson: SEA Games fund put in foundation like ‘Napoles case’ Sports Related Videospowered by AdSparcRead Next LATEST STORIES Robredo: True leaders perform well despite having ‘uninspiring’ boss PLAY LIST 02:49Robredo: True leaders perform well despite having ‘uninspiring’ boss02:42PH underwater hockey team aims to make waves in SEA Games01:44Philippines marks anniversary of massacre with calls for justice01:19Fire erupts in Barangay Tatalon in Quezon City01:07Trump talks impeachment while meeting NCAA athletes02:49World-class track facilities installed at NCC for SEA Games 5-way PBA Govs’ Cup race for 3 premium slots Trump to designate Mexican drug cartels as terrorist groups Ethel Booba on hotel’s clarification that ‘kikiam’ is ‘chicken sausage’: ‘Kung di pa pansinin, baka isipin nila ok lang’ Argentine bishop appears at court hearing on abuse chargescenter_img MOST READ No more menthol cigarettes: New ban on tobacco, vape flavors Winter storm threatens to scramble Thanksgiving travel plans Hotel says PH coach apologized for ‘kikiam for breakfast’ claim View comments In the chief support, Jonas Sultan trounced former world champion Johnriel Casimero by scores of 116-112, 117-111, 115-113.He earned the right to challenge countryman Jerwin Ancajas for the IBF super lightweight title.Other bouts saw a fading Jason Pagara earn a split draw against late replacement James Onyango of Kenya in a welterweight bout and King Arthur Villanueva beat Richie Mepranum by third round technical knockout in a bantamweight tussle.Rising star Kevin Jake Cataraja of Cebu climbed to 7-0 with six KOs following a second round stoppage of Gen. Santos City’s Wiljan Ugbaniel. —ROY LUARCAADVERTISEMENT The Cagayan de Oro native dominated the early goings, but Hekkie found his bearing starting in the fourth and engaged the Filipino in furious exchanges on several occasions.An accidental headbutt produced a cut on Melindo’s left eye, which was compounded by another bloody cut on the right eye in the 10th round.FEATURED STORIESSPORTSSEA Games: Biñan football stadium stands out in preparedness, completionSPORTSPrivate companies step in to help SEA Games hostingSPORTSBoxers Pacquiao, Petecio torchbearers for SEA Games openingDespite blurry vision, however, Melindo fought with energy and fury to earn the nod of judges Takeo Harada, 117-110, and Glenn Trowbrudge, 115-112. Judge Carl Zappia saw Budler the winner, 115-113.The 29-year-old Melindo raised his record to 37-2 with 13 knockouts, while Budler, also 29 and also nicknamed “The Hexecutioner.” fell to 31-3 (10 KOs). Don’t miss out on the latest news and information. last_img read more

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Players running down contracts will become a norm, says Arsene Wenger

first_imgPlayers running down their contracts will become the norm in years to come due to skyrocketing transfer fees, Arsenal manager Arsene Wenger has said.Alexis Sanchez and Mesut Ozil have both entered the final year of their deals, while Alex Oxlade-Chamberlain, Santi Cazorla, Jack Wilshere and Kieran Gibbs could also leave Arsenal for free in 12 months’ time.Wenger tried to see the positive side, saying it could be an “ideal situation” for the club as the players would be motivated to perform to impress potential suitors.”I think in the future, you will see it more and more. Why? Because the transfers are so high, even for normal players,” he told reporters on Sunday.”You will see more and more players going into the final year of the contract because no club will want to pay the amount demanded…in the next 10 years, it will become usual.”I think the performance on the day does not depend on the length of the contract, if that was true we would sign everyone for 20 years and be happy.”ALEXIS SANCHEZ SAGA WON’T BE A DISTRACTIONSanchez, who was Arsenal’s top scorer in the Premier League with 24 goals last season, has been linked with a move to Paris St Germain in the French media, but Wenger was adamant he would stay at the Emirates Stadium.”Do I think he will stay? Yes, of course. How many times did I tell you that?,” the Frenchman added.”One day, he will go and Arsenal will go on. We will all go one day and Arsenal, hopefully, will go on.”advertisementWenger has insisted that the transfer saga of Alexis Sanchez won’t be a distraction to the club this season.Manchester City, Chelsea, Paris Saint Germain, Bayern Munich and Juventus have all been linked with the 28-year-old. However, the Arsenal boss appears determined to hold onto the 28-year-old for the last year of his deal.Wenger, who in the past has sold the Samir Nasri and Robin van Persie to avoid losing them for free when their contracts expired, is however sticking to his guns over Sanchez.”Nobody knows if Sanchez will extend his contract here. What can I do about that? One day he will go and Arsenal will go on. Of course I think he will stay. How many times do I have to tell you?” he added.It is expected that Manchester City will bid 50 million pound for the 28-year-old whose current deal with Arsenal is set to end in 2018.Arsenal will begin their league campaign against Leicester on August 12.last_img read more

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