Use null instead of empty string, fix all string checks

code/modules/hydroponics/gene_modder.dm

@@ -279,9 +279,9 @@
 			dat += "</div>"
 
 		dat += "<div class='line'><h3>Variant</h3></div><div class='statusDisplay'><table>"
-		dat += "<tr><td width='260px'>[(seed.variant == "") ? "None" : seed.variant]</td>"
+		dat += "<tr><td width='260px'>[seed.variant ? seed.variant : "None"]</td>"
 		dat += "<td><a href='?src=[UID()];set_v=1'>Edit</a></td>"
-		if(seed.variant != "")
+		if(seed.variant)
 			dat += "<td><a href='?src=[UID()];del_v=1'>Remove</a></td>"
 		dat += "</tr></table></div>"
 	else
@@ -405,7 +405,7 @@
 	else if(href_list["del_v"])
 		if(!seed)
 			return
-		seed.variant = ""
+		seed.variant = null
 		seed.apply_variant_name()
 
 	interact(usr)

code/modules/hydroponics/grown.dm

@@ -42,7 +42,7 @@
 		seed.prepare_result(src)
 		transform *= TRANSFORM_USING_VARIABLE(seed.potency, 100) + 0.5 //Makes the resulting produce's sprite larger or smaller based on potency!
 		add_juice()
-		if(seed.variant && seed.variant != "")
+		if(seed.variant)
 			name += " \[[seed.variant]]"
 
 /obj/item/reagent_containers/food/snacks/grown/Destroy()

code/modules/hydroponics/hydroponics.dm

@@ -344,7 +344,7 @@
 /obj/machinery/hydroponics/examine(user)
 	. = ..()
 	if(myseed)
-		if(myseed.variant != "")
+		if(myseed.variant)
 			. += "<span class='info'>It has the <span class='name'>[myseed.variant]</span> variant of <span class='name'>[myseed.plantname]</span> planted.</span>"
 		else
 			. += "<span class='info'>It has <span class='name'>[myseed.plantname]</span> planted.</span>"

code/modules/hydroponics/seeds.dm

@@ -339,11 +339,13 @@
 	if(!adj.Adjacent(user) || isnull(V))
 		return
 	variant = copytext(sanitize(html_encode(trim(V))), 1, 64)
+	if(variant == "")
+		variant == null
 	to_chat(user, "<span class='notice'>You [variant ? "change" : "remove"] the [plantname]'s variant designation.</span>")
 	apply_variant_name()
 
 /obj/item/seeds/proc/apply_variant_name()
-	var/V = (variant == "") ? "" : " \[[variant]]" // If we have a non-empty variant add it to the name
+	var/V = variant ? " \[[variant]]" : "" // If we have a non-empty variant add it to the name
 	var/N = initial(name)
 	if(copytext(name, 1, 13) == "experimental") // Don't delete 'experimental'
 		N = "experimental " + N