Corn (Zea mays)
The Latin name for this species is mays and maize is the correct title for this group of plants. The plants many of us grow for corn on the cob, or “sweet corn” as it is sometimes called, is Z. mays ssp. rugosa, and was cultivated for its high sugar content. Many varieties of maize are grown for dried, fully mature seed, which is eaten as a grain, but sweet corn is picked before the seeds mature fully, before its sugars convert back into starch. This is why fresh corn must be eaten fairly quickly after harvest, before it degrades and becomes starchy. Many hybrids have been developed that retain their sweetness for longer periods, mature uniformly, and ship well.
Maize, including sweet corn, is produced in terrific quantities throughout the Americas, with the United States growing over 300 million metric tons each year alone. The crop was grown and celebrated by Mesoamerican peoples as long as 9,000 years ago, and forms the dietary base for scores of early American civilizations. Many Indian tribes also exploited the plant for its medicinal qualities: The Cherokee used it to treat skin blemishes and kidney stones; the Navajo created a poultice for sore throats; and the Tewa used it as to treat swelling, heart palpitations, and as an aid for menstruating women. The Iroquois people provided the first record of growing sweet corn to European settlers in 1779.
Corn, however it is eaten, is high in carbohydrates, sugars, protein, vitamins, magnesium, and potassium. The edible portions of sweet corn contain about 75% water. Cooking reduces the amount of usable vitamin C in sweet corn, but increases the quantity of ferulic acid, which is thought to be a powerful antioxidant, and seems to provide several health benefits.
The original corn, called “field corn,” had a high content of starch over sugar. Sweet corn occurs as a mutation in field corn and was grown by several Native American tribes. The Iroquois gave the first recorded sweet corn (called papoon) to European settlers in 1779. It soon became a popular food.
Crop breeders isolated several cultivars of sweet corn that would produce genetically similar offspring seeds. These include Golden Bantam, Pink Popcorn, Calico Popcorn, and Bloody Butcher. There are many others, including quite a few Mexican varieties.
Hybridization crosses the pollen of one variety with the receptive female flowers of another. The seeds that result are hybrid seeds. Hybridization allowed for more uniform maturity, improved quality, and disease resistance.
The genes that enhance the sugar content and shelf life of sweet corn are carried in the plants’ pollen. In order for the genetic expression to be true, the variety may need to be isolated to prevent cross-pollination. SU, SE, and SH2 are the names of isolated gene groups. These are hybrids, not GMO / GEO.
SU varieties (developed circa 1902) have modest amounts of sugar in their kernels, and they tend to have decent corn flavor. But their conversion of sugar to starch is rapid, so they have a narrow harvest window before flavour deteriorates. They tend to have good plant vigour. To avoid cross-pollination and poor quality, SU varieties must be isolated from field corn and popcorn. They must also be isolated from the supersweet (sh2) group.
The SE gene (developed in the 1950s) gives varieties improved eating quality over SU varieties by slightly increasing the level and changing the types of sugars in the kernels. SE varieties also have a very tender pericarp (the outer layer of the kernel). The SE gene does not slow the conversion of sugars to starch but the harvest window is slightly longer than with SU varieties because of elevated sugar levels. SE varieties do not require isolation from SU varieties, but they do require isolation from SH2 and field or popcorn.
Supersweet or shrunken-2 types (also 1950s) have four to ten times the sugar content of normal sugar (SU) types and with proper handling are able to be stored for up to 10 days. They are less hardy than even sugary extender (SE) types, requiring higher soil temperature for germination, precise planting depth, and isolation from all other corn pollen for optimum results. The name derives from the shrunken, shrivelled appearance of the dried kernel which is low in starch. The SH2 gene slows the conversion of simple sugars to starch, so supersweet varieties have a much wider harvest window than other types.
Synergistic varieties combine more than one line of genetics on the same ear. The first varieties developed of this type have 25% sh2, 25% se and 50% su kernels on the cob, but now different combinations are possible. There is an increasing number of brand names and trademarks that cover specific genetic combinations under this general type.
The town of Jarvis, in southern Ontario, celebrates Cornfest each August. Jarvis really lets its hair down as it hosts a serious baseball competition, car show, live music, equestrian events, crafts, a midway, and of course, lots and lots of corn to eat.
Kwa mfano, mahindi (Zea mays) ni aina ya mahindi ya asili ya Amerika, ambayo kwa Kiingereza inaitwa mays, na mahindi (maize) ni jina la asili la mahindi. Mimea ambayo wengi wetu tunakua kwa ajili ya mahindi kwenye makapi, au "mahindi matamu" kama inavyoitwa nyakati nyingine, ni Z. mays ssp. Rugosa, na ililimwa kwa ajili ya maudhui yake ya juu ya sukari. Aina nyingi za mahindi hukuzwa kwa ajili ya mbegu kavu, zilizokomaa kabisa, ambazo zinatumiwa kama nafaka, lakini mahindi matamu huchukuliwa kabla ya mbegu kukomaa kabisa, kabla ya sukari zake kubadilishwa kuwa wanga. Kwa hiyo, mahindi safi yanapaswa kuliwa upesi baada ya kuvunwa, kabla ya kuharibika na kuwa na wanga. Mimea mingi iliyochanganywa imeanzishwa ambayo huhifadhi ladha yake kwa muda mrefu, hukomaa kwa usawa, na husafirishwa vizuri. Mahindi, pamoja na mahindi matamu, hutengenezwa kwa wingi sana katika Amerika, na Marekani pekee inazalisha zaidi ya tani milioni 300 kila mwaka. Mazao hayo yalikua na kusherehekewa na watu wa Mesoamerica miaka 9,000 iliyopita, na yanaunda msingi wa lishe kwa idadi kubwa ya ustaarabu wa mapema wa Amerika. "Kama vile watu wa kabila la Cherokee walivyotumia dawa za mimea hiyo, watu wa kabila la Navajo walitumia dawa za kuondoa maumivu ya koo, na watu wa kabila la Tewa walitumia dawa za kuondoa uvimbe, na pia za kuondoa maumivu ya moyo.""" Watu wa kabila la Iroquois walianzisha kilimo cha mahindi kwa mara ya kwanza katika 1779. Mahindi, hata iwe yanakulawa kwa njia gani, yana wanga mwingi, sukari, protini, vitamini, magnesiamu, na potasiamu. Sehemu ya mahindi yenye ladha ya sukari ina maji asilimia 75. Kupika hupunguza kiasi cha vitamini C katika mahindi ya sukari, lakini huongeza kiasi cha asidi ya ferulic, ambayo inaonekana kuwa antioxidant yenye nguvu na inaonekana kutoa faida kadhaa za afya. Mahindi ya awali, yaliyoitwa "mahindi ya shamba", yalikuwa na kiasi kikubwa cha wanga kuliko sukari. Mahindi matamu hutokea kama mabadiliko katika mahindi ya shamba na yalilimwa na makabila kadhaa ya Wenyeji wa Asili wa Amerika. Wamarekani walianza kulima mahindi ya aina ya papoon mwaka 1779. Punde si punde ikawa chakula maarufu. Wafugaji wa mazao walijitenga na aina kadhaa za mahindi matamu ambayo yangetokeza mbegu za watoto waliofanana kimetaboliki. Hizi zinatia ndani Golden Bantam, Pink Popcorn, Calico Popcorn, na Bloody Butcher. Kuna aina nyingine nyingi, kutia ndani aina kadhaa za Mexico. Mzunguko huo huchanganya chavua ya aina moja na maua ya kike ya aina nyingine. Mbegu zinazotokezwa ni mbegu za mchanganyiko. Mzunguko huo ulifanya mimea hiyo iwe na ukomavu sawa, iwe na ubora bora, na iwe sugu kwa magonjwa. Jeni zinazozidisha kiasi cha sukari na muda wa kuhifadhiwa kwa mahindi matamu hubebwa katika chavua ya mimea. Ili usemi wa maumbile uwe wa kweli, huenda aina hiyo ikahitaji kutengwa ili kuzuia chavua ya msalaba. SU, SE, na SH2 ni majina ya vikundi vya jeni vilivyojitenga. Hii ni hybrids, sio GMO. Aina za SU (zilizotengenezwa karibu na 1902) zina kiasi kidogo cha sukari katika mbegu zao, na huwa na ladha nzuri ya mahindi. Lakini wao kubadilisha sukari kwa wanga ni haraka, hivyo wana dirisha nyembamba mavuno kabla ya ladha kuharibika. Wao huwa na nguvu nzuri ya mimea. Ili kuepuka msalaba-pollination na ubora duni, aina SU lazima kutengwa kutoka mahindi shamba na popcorn. Pia lazima zitenganishwe na kundi la supersweet (sh2). Jeni ya SE (iliyotengenezwa katika miaka ya 1950) inatoa aina bora ya kula kuliko aina za SU kwa kuongeza kidogo kiwango na kubadilisha aina za sukari katika nyuzinyuzi. Aina za SE pia zina pericarp nyembamba sana (safu ya nje ya kernel). Jeni ya SE haipunguzi mabadiliko ya sukari kuwa wanga, lakini dirisha la mavuno ni ndefu kidogo kuliko aina za SU kwa sababu ya viwango vya sukari vilivyoinuka. Aina za SE hazihitaji kutengwa kutoka kwa aina za SU, lakini zinahitaji kutengwa kutoka kwa SH2 na popcorn. Supersweet au shrunken-2 aina (pia 1950s) ina mara nne hadi kumi sukari ya aina ya kawaida ya sukari (SU) na kwa utunzaji sahihi wanaweza kuhifadhiwa kwa hadi siku 10. Ni chini ya hardy kuliko hata aina ya sukari extender (SE), ambayo inahitaji joto la udongo kwa ajili ya kuota, kina cha kupanda sahihi, na kutengwa kutoka kwa chavua nyingine zote kwa matokeo bora. Jina linatokana na kuanguka, kuharibika kuonekana ya kernel kukaushwa ambayo ni chini katika starch. SH2 inaongeza kasi ya kubadilisha sukari rahisi kuwa wanga, na hivyo aina za super-sweet zina nafasi kubwa ya kuvuna kuliko aina nyingine. Aina za synergistic huchanganya zaidi ya mstari mmoja wa chembe za urithi kwenye sikio moja. Aina ya kwanza ya aina hii ina 25% sh2, 25% se na 50% su kernels kwenye cob, lakini sasa mchanganyiko tofauti ni uwezekano. Kuna idadi inayoongezeka ya majina ya bidhaa na alama za biashara ambazo hufunika mchanganyiko maalum wa maumbile chini ya aina hii ya jumla. Jiji la Jarvis, kusini mwa Ontario, huadhimisha Sherehe ya Mahindi kila Agosti. Jarvis ni moja ya maeneo maarufu zaidi ya mji wa Miami, na ina mashindano ya baseball, maonyesho ya magari, muziki wa moja kwa moja, mashindano ya farasi, ufundi, na chakula cha mchana.