Fun with Flowers: The art of squash breeding at Cornell University

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Winter squash in the spring?  Yes.  Should you care?  Yes, but why?  Have you ever thought about why the carrots at the store are orange or why the tomatoes are always red?  Does it have to be this way?  The short answer is no.  As it turns out, these colors, shapes and sizes have more to do with human selection than any "fact" of nature.  At the beginning of my journey, the question was where does food come from?  This lead to the farm.  Taking things a bit further, the question became, where do all the seeds come from to grow the food on those farms?  In an interesting twist, while exploring the beautiful, natural diversity of northern California's agricultural scene, I got an unexpected email that lead me back to the northeast, where I am currently working at Cornell University, an institution at the heart of northeastern food production.  I'm working in the department of Plant Breeding and Genetics with Dr. Mazourek and his team.  Through surveys and direct communication with farms, they figure out the biggest challenges facing farmers in growing our favorite annual vegetables.  Who knew so much thought and so many people went into those little cucumber slices (not to mention all the other veggies) we eat everyday in our salads?  Behind every delicious bite of food is a massive web of research, people, farms and institutions working to protect and progress our food system.

  The goal is to develop stronger, tastier, more disease/pest resistant varieties of our favorite everyday foods.  With a current focus on the cucurbit family (e.g. squash, melons, watermelons, cucumbers, gourds) as well as research on peas and peppers, this team gets to the crux of solving these problems through traditional plant breeding.  This is the natural, methodical, ancient process of pairing two plants together, with desirable traits and observing, selecting and experimenting with the best of each new generation.  In conjunction with nature's methods, we are fighting the war against disease and pest pressures that can restrict and limit growers from producing food locally.  The research spans a number of different specific crop traits and as I get more involved in these projects, I will continue to share that knowledge.

  Today we are looking into the basics of pollination.  Last year, while working at the Stone Barns Center, we touched on the basics of pea pollinations and got some great feedback from readers working on similar projects (click here for a refresher).  With peas, we looked at pollinating perfect flowers.  Unlike a pea, which can pollinate itself, squash have separate male and female flowers, which require...



pollinators such as bees, butterflies, or even humans.


When breeding, each day the first task is to check all plants for females.  Although the male (see image 1) and female flowers (see image 2) look similar, you can easily tell them apart based on the immature fruit (or ovary) present below the female squash flower.

As you can see in image 1, there is no bulge below the sepals, that's how we know it's a male.  The males get plucked off for use of their pollen.

Image 1: male flower

Here we can see the immature fruit.

Image 2: female flower 

Wrapped inside the protective female flower is the stigma, which receives the male pollen.  Sliding down the style, pollen accesses the ovary where it swells to become fruit.  When breeding, it is ideal to find flowers that are about to open and have not already opened.  The window for good pollination is short and if the female is open waiting for a male, she will wilt and die.

It's good to gently feel the bulge to test if it is firm.  If it's brown or mushy, she won't take and there is no need to pollinate that female.

After identifying a good female, pinch off male flowers from the plant you want to make this cross-pollination or self-pollination.  

Gently peel back the pedals of both flowers to completely expose the male anthers containing pollen and the female's stigma.

Check the male for good pollen, which means it's not too clumpy and can easily come off.

Using the male as a little paint brush, 

dab the pollen onto the stigma, like an impressionist using short strokes.

Finally, we tie an id tag around the fruit with all the pertinent information (which plants were used and the date) and clip on a protective bag to prevent any water from getting in.

If the fruit takes, it swells and eventually...

Within each new seed gathered from these initial trials, vast amounts of traits exist, some with stronger disease resistance, different color expressions, some smaller than others, so many capabilities.  Through patience and experimentation, we can narrow down, cross-breed and create vegetable varieties with the most ideal qualities for growers and consumers.